JP5370118B2 - Information recording apparatus and light beam generating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high-reliability devices capable of acquiring composite light which has sufficiently high intensity, in an information recording device and an optical-beam generating device which uses a light generated by combining a plurality of light beams with one another. <P>SOLUTION: The information recording device includes a light source 190, and a thermally assisted magnetic head 110. Each component and a function are described, as in the following section. The light source 190 includes a plurality of light-emitting parts for emitting light beams with differing frequencies, and a minimum frequency difference &Delta;f among a plurality of light beams emitted from the plurality of light-emitting parts is set larger than a recording frequency fm, corresponding to the shortest recording length of an information recording medium 300. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an information recording apparatus and a light beam generating apparatus, and more particularly to an information recording apparatus and a light beam generating apparatus having a function of combining a plurality of lights to generate one light beam.

  Conventionally, various recording apparatuses using laser light have been developed. One of them is an information recording apparatus using a heat-assisted magnetic recording system.

  The heat-assisted magnetic recording method is attracting attention as a next-generation information recording technology for HDD (Hard Disk Drive). In this method, a predetermined area of a recording layer made of a magnetic material is irradiated and heated to reduce the coercivity of the recording layer, and information recording is performed by applying a magnetic field to the area where the coercivity is reduced.

  As a light source used for the heat-assisted magnetic recording apparatus, a magnetic recording apparatus using a VCSEL (Vertical Cavity Surface Emitting LASER) has been proposed (for example, see Patent Document 1). VSCEL not only consumes less power and has a smaller laser size than a general Fabry-Perot laser, but also enables high-speed modulation driving. Therefore, when a VCSEL is used as the light source of the heat-assisted magnetic recording apparatus, the transfer speed can be further increased.

  In addition to the heat-assisted magnetic recording apparatus, as a recording apparatus using laser light, for example, a laser beam recording apparatus that records a desired image on a recording paper using laser light has been proposed (for example, see Patent Document 2). ).

  In Patent Document 2, a desired image is recorded by irradiating a recording paper with a plurality of laser beams whose intensity is modulated by an image recording signal. In the technique proposed in Patent Document 2, light emitted from a plurality of laser light sources having wavelengths that are separated to some extent is collected by the same optical system. At that time, the combined light of a plurality of lights having different spot sizes is irradiated onto the recording paper by utilizing the fact that the condensing position of each outgoing light is shifted. In this case, the light energy of the large spot size light is added to the small spot size light, and the light intensity of the small spot size light can be increased.

JP 2005-78689 A Japanese Patent Laid-Open No. 06-234226

  In the above-mentioned Patent Document 1, a technique using a VCSEL as a light source is proposed in a heat-assisted magnetic recording apparatus. However, since the optical output of the VCSEL is smaller than that of a Fabry-Perot laser, the intensity required for the heat-assisted magnetic recording. May not be able to generate stable light. As a method for solving this problem, as proposed in Patent Document 2, a method of multiplexing a plurality of lights is conceivable.

  However, when the technique described in Patent Document 2 is applied to a heat-assisted magnetic recording apparatus, light having a large spot diameter is also irradiated to the recording medium, and thus heating is performed to an unnecessary area. In this case, energy efficiency is deteriorated, and there is a possibility that a problem of reduced reliability may occur.

  In order to solve the above various problems, a method of combining a plurality of lights having the same wavelength is also conceivable. However, when the present inventor examined various configurations for such a configuration, in practice, it is difficult to perfectly match the wavelengths of a plurality of lights, and thereby it is possible to obtain combined light having stable light intensity. It turned out to be difficult.

  The present invention has been made in view of the above situation. An object of the present invention is to provide an information recording apparatus and a light beam generating apparatus that use light generated by combining a plurality of lights, and capable of obtaining combined light with sufficient light intensity and having high reliability. Is to provide.

  In order to solve the above problems, an information recording apparatus of the present invention is configured to include a light source and a heat-assisted magnetic head, and the configuration and function of each unit are as follows. The light source has a plurality of light emitting portions that emit light having different frequencies, and the minimum frequency difference Δf between the plurality of lights respectively emitted from the plurality of light emitting portions corresponds to the shortest recording length of the information recording medium. Greater than frequency fm. The heat-assisted magnetic head performs heat-assisted magnetic recording of information on the information recording medium using the combined light of a plurality of lights emitted from the light source.

  Moreover, the light beam generation apparatus of this invention is set as the structure provided with a light source and a light beam emission part, and the structure and function of each part are as follows. The light source includes a plurality of light emitting units that emit light having different frequencies, and a minimum frequency difference between the plurality of lights respectively emitted from the plurality of light emitting units is greater than a frequency corresponding to the shortest light emission time. The light beam emitting unit multiplexes a plurality of lights emitted from the light source and emits the combined light beam.

  As described above, the information recording apparatus and the light beam generating apparatus of the present invention include a light source having a plurality of light emitting portions that emit light having different frequencies, and records the minimum frequency difference between the plurality of lights to be combined in the shortest recording time. The frequency is set higher than the frequency corresponding to the long (shortest light emission time). According to the present invention, by configuring the light source in this way, it is possible to provide a highly reliable apparatus that can obtain combined light with sufficient light intensity. The principle of obtaining this effect will be described in detail later.

It is a figure for demonstrating the problem of the low frequency noise which generate | occur | produces when a some coherent light is combined. It is a figure for demonstrating the problem of the low frequency noise which generate | occur | produces when a some coherent light is combined. This is an ideal time-varying characteristic of recording light and recording magnetic field during heat-assisted magnetic recording. It is a time change characteristic of the recording light and the recording magnetic field at the time of thermally assisted magnetic recording when there is an influence of low frequency noise. 1 is a schematic configuration diagram of a thermally-assisted magnetic recording apparatus according to a first embodiment. FIG. 3 is an enlarged side view of the vicinity of a flying slider head in the heat-assisted magnetic recording apparatus of the first embodiment. FIG. 2 is a schematic cross-sectional view of the vicinity of a thermally assisted magnetic head in the thermally assisted magnetic recording apparatus of the first embodiment. FIG. 3 is a schematic configuration diagram of a recording light generation unit in the thermally-assisted magnetic head of the first embodiment. It is a schematic block diagram of the condensing part in the heat-assisted magnetic head of 1st Embodiment. It is a schematic block diagram of the light emission part in the heat-assisted magnetic head of 1st Embodiment. It is a figure which shows the example of 1 structure of the light source in the heat-assisted magnetic recording device of 1st Embodiment. FIG. 10 is a schematic configuration diagram of a light condensing unit in a heat-assisted magnetic head of Modification 1; FIG. 10 is a schematic configuration diagram of a recording light generation unit in a heat-assisted magnetic head according to Modification 2. FIG. 10 is a schematic configuration diagram of an optical system in a heat-assisted magnetic recording apparatus of modification example 3. FIG. 10 is a schematic configuration diagram of an optical system in a heat-assisted magnetic recording apparatus of modification example 4. FIG. 10 is a schematic configuration diagram of a recording light generation unit in a heat-assisted magnetic head of Modification Example 5. FIG. 10 is a schematic configuration diagram of a light condensing unit in a heat-assisted magnetic head of Modification Example 6. FIG. 10 is a schematic configuration diagram of a light collecting unit in a heat-assisted magnetic head of Modification Example 7. It is a schematic block diagram of the vicinity of the heat-assisted magnetic head of the heat-assisted magnetic recording apparatus according to the second embodiment. It is a figure for demonstrating the condensing operation | movement in the heat-assisted magnetic head of 2nd Embodiment. It is a schematic block diagram of the light source in the heat-assisted magnetic recording device of 3rd Embodiment.

Hereinafter, a configuration example of a thermally-assisted magnetic recording apparatus according to an embodiment of the present invention will be described in the following order with reference to the drawings. In addition, this invention is not limited to the following examples.
1. First Embodiment: Configuration Example of Thermally Assisted Magnetic Recording Device that Condenses Incident Light from Multiple Light Sources with Grating Coupler 2. Various modifications of the heat-assisted magnetic recording apparatus according to the first embodiment. Second embodiment: Configuration example of a thermally-assisted magnetic recording apparatus in which the incident direction of incident light is the same as the extending direction of the optical waveguide. Third Embodiment: Configuration Example for Equivalent Equivalent Resistance of Each Light-Emitting Unit in a Light Source

<1. First Embodiment>
Before describing the configuration of the thermally-assisted magnetic recording apparatus according to the first embodiment of the present invention, problems that occur when the recording light is generated by combining the light emitted from the plurality of light sources, and a method for solving the problem The (operation principle of the present invention) will be described in more detail.

[Influence of low frequency noise and its solution]
When combining a plurality of lights to increase the intensity of the recording light, it is preferable to use a plurality of light sources of the same type from the viewpoint of cost. Ideally, it is preferable that the wavelength difference Δλ (frequency difference Δf) and the phase shift between the plurality of lights are zero. However, in practice, it is difficult to realize such an ideal state due to, for example, manufacturing variations of light sources. Therefore, even when a plurality of light sources of the same type are used, a slight frequency difference Δf occurs between the plurality of lights.

  Therefore, the present inventor has examined the influence of the case where there is a frequency difference Δf (wavelength difference Δλ) between a plurality of lights. In this case, interference occurs between the plurality of lights, and low-frequency noise is generated. It was found to occur.

  Specifically, as a result of verifying a state where light emitted from a plurality of light sources (for example, VCSELs) whose wavelengths are close to each other and have a long coherent length are collected and combined at the same location, the lights interfere with each other. It was found that low frequency noise was generated. Further, in this case, it has been found that there is no phase correlation between the plurality of lights and it is difficult to control the correlation between the plurality of lights, so that noise that is difficult to predict is generated.

  When the low-frequency noise that is difficult to predict as described above is about the recording frequency when information is recorded on the recording medium, the recording light intensity varies with time during the heat-assisted magnetic recording, and the heat application state May not be in a desired state and accurate information recording may not be performed. Hereinafter, this problem will be described more specifically with reference to the drawings.

Here, a case where two lights having a frequency difference of Δf (> 0) are combined is considered. In this case, ₁ and E ₂ each electric field E of the two light is represented by the following formula.

  The light intensity (electric field strength) of each light is obtained by squaring the electric field and is represented by the following formula.

The light intensity | E ₁ + E ₂ | ² of the combined light of the two lights is represented by the following equation.

  Now, since the case where the frequency difference Δf between the two lights is small (f> Δf) is considered, the last term (cos [2π (Δf) t]) on the right side in Equation 3 is the lowest frequency component. .

Here, FIG. 1 shows characteristics (calculation results) of the light intensities | E ₁ | ² and | E ₂ | ² when f = 1 and Δf = 0.1 in the above formula 2. In the characteristics shown in FIG. 1, it takes a time t on the horizontal axis, the light intensity on the vertical axis _| E 1 ^{| 2} and _| take ^{2 |} E 2. The broken line characteristic light intensity in FIG. 1 | a characteristic of ^2, solid characteristic light intensity | | E ₁ is a characteristic of ² | E _2. FIG. 2 shows the characteristic (calculation result) of the light intensity | E ₁ + E ₂ | ² of the combined light when f = 1 and Δf = 0.1 in the above equation 3. In the characteristic of FIG. 2, the horizontal axis represents time t, and the vertical axis represents light intensity | E ₁ + E ₂ | ² .

As shown in FIG. 1, when a frequency difference Δf exists between two lights, the phase difference between the two lights varies with time. As a result, when two lights are combined, the light intensity | E ₁ + E ₂ | ² of the combined light periodically fluctuates at a low frequency with respect to time, as indicated by a broken line in FIG. Optical beat noise occurs). The envelope of fluctuation of the light intensity | E ₁ + E ₂ | ² (broken line in FIG. 2) corresponds to the component of the term cos [2π (Δf) t] of the lowest frequency component in the above equation 3.

  That is, when combining light emitted from a plurality of light sources in order to increase the intensity of the recording light, if the wavelengths of the combined light are close to each other and each light is a light having a long coherent length, Low frequency noise is generated in the intensity of wave light.

  However, when a plurality of incoherent lights such as light emitted from LEDs (Light Emitting Diodes) are combined, for example, the above-mentioned low frequency noise is not observed because the fundamental frequency f of each LED varies greatly. In addition, even when a light source that emits light having a long coherent length, such as a DFB (Distributed Feedback) laser or VSCEL, is used as a light source, the frequency and phase of a plurality of lights to be combined are perfectly matched (ideal In the state), no low frequency noise is observed.

  Here, the problem that occurs when the above-mentioned low-frequency noise is present in the recording light when performing heat-assisted magnetic recording on the recording medium will be described more specifically with reference to the drawings.

  FIGS. 3A and 3B show ideal characteristic examples of recording light emission characteristics and recording magnetic field application characteristics in the heat-assisted magnetic recording system, respectively. Now, as shown in FIG. 3 (a), the recording light is applied to the recording medium during the time t0 to t1, and the recording magnetic field is in the range between the times t0 and t1 and between the times t2 and t3. Consider a case where the voltage is applied between times t4 and t5 (t0 <t2 <t3 <t4 <t5 <t1).

  In this example, the time between time t2 and t3 is the magnetic field application time corresponding to the shortest recording length (shortest recording cycle Tmin), and the time between time t4 and t5 is about three times the shortest recording cycle Tmin. explain. Also, the dotted line in FIG. 3A is the lower limit (threshold value) of the light intensity that can be thermally assisted magnetic recording. That is, in the example shown in FIGS. 3A and 3B, information is recorded on the recording medium by heat-assisted magnetic recording between times t2 and t3 and between t4 and t5.

  On the other hand, FIGS. 4A and 4B show an example of the recording light emission characteristic and the recording magnetic field application characteristic when low frequency noise is generated in the light intensity of the recording light, respectively.

  If low-frequency noise exists in the light intensity of the recording light, the light intensity fluctuates in a low-frequency cycle as shown in FIG. As a result, a time period in which the light intensity falls below the light intensity threshold (dotted line in FIG. 4A) necessary for the heat-assisted magnetic recording occurs between the times t0 and t1. If the time zone in which the light intensity falls below the threshold value (dotted line in FIG. 4A) due to low-frequency noise and the application time of the recording magnetic field overlap, heat-assisted magnetic recording cannot be performed in that time zone, and desired recording can be performed. The mark cannot be formed on the recording medium. For example, in the example shown in FIGS. 4A and 4B, the heat-assisted magnetic recording is not possible at times t6 to t7 (t4 <t6 <t7 <t5) between times t4 and t5.

  The above-mentioned problem of the low frequency noise of the light intensity during the heat-assisted magnetic recording is that the frequency of the low frequency noise is about the recording frequency corresponding to the shortest recording length or less (the frequency of the low frequency noise is the shortest recording length). (When the recording light irradiation period corresponds to or more). In particular, the problem of low frequency noise (optical beat noise) is likely to occur when a light source that emits light having a long coherent length, such as VSCEL, is used as the light source.

  As one method for solving the above-mentioned problem, it is conceivable that the frequencies (wavelengths) are perfectly matched between the two lights to be combined. It is difficult to realize an ideal state. Moreover, even if the frequencies of the two lights can be perfectly matched, if the phases of the two lights differ by 180 degrees, they completely cancel each other within the coherent length range, and the intensity of the combined light decreases. .

  Therefore, in the present invention, in order to solve the above problem, the frequency (wavelength) is not completely matched between the two lights to be multiplexed, but a predetermined frequency difference Δf is set in advance between the plurality of lights, Increase the frequency of the low frequency noise generated in the combined light. Specifically, the frequency component of the low-frequency noise corresponds to the component (cos [2π (Δf) t]) of the frequency difference Δf between the two lights to be combined, as described in Equation 3 above. Therefore, in the present invention, the frequencies (wavelengths) between the two lights to be combined are made different from each other so that the frequency difference Δf between the two lights to be combined is sufficiently higher than the recording frequency corresponding to the shortest recording length. . For example, when the shortest recording length is about 1 nsec, the corresponding recording frequency is about 1 GHz. Therefore, the frequency difference Δf between the two lights to be combined is adjusted to be sufficiently higher than about 1 GHz. .

  If the frequency difference Δf between the two lights to be combined is higher than the recording frequency corresponding to the shortest recording length, even if the recording light intensity fluctuates during the period corresponding to the shortest recording length, at least once in that period. The light intensity can be increased above the threshold required for heat-assisted magnetic recording. The recording response of the recording medium in such a situation is similar to the situation in which the recording light with the average light intensity is irradiated, and the above-described problem of erroneous recording of information is solved. Therefore, in the present invention, the frequency of the low frequency noise (= Δf) generated between the two lights is increased in advance to a value that does not cause the above-described problem of the low frequency noise. A frequency difference Δf is set. For example, the wavelength difference Δλ of two lights is set to 0.1 nm, and the frequency difference Δf (frequency of low frequency noise) between the two lights is set to about 40 GHz.

Here, a condition for deriving the frequency (= Δf) of the low-frequency noise generated between the two lights to a value that does not cause the above-described low-frequency noise problem is derived. First, when the above equation 1 is rewritten using the wavelength λ, the following equation is obtained. In the following formula, “c” is the speed of light, which is about 3 × 10 ⁸ [m / s].

  When the frequency (= Δf) of the low frequency noise is obtained from the above equation 4, it is as follows. However, in the following formula, it is approximated as Δf << f.

  That is, it can be seen from the above formula 5 that the frequency (= Δf) of the low frequency noise can be increased by increasing the wavelength difference Δλ between the two lights.

  In the present embodiment, the wavelength difference Δλ between the two lights to be combined is increased within a range satisfying the assumption of Δf << f, and the frequency difference Δf between the two lights is set to the recording frequency fm corresponding to the shortest recording length. Make it bigger. That is, by setting the wavelengths of the two lights to be combined so as to satisfy the following expression, the above-described problem of low frequency noise (optical beat noise) can be solved.

  In the above description, an example in which recording light is generated by combining two lights has been described, but even in the case where light emitted from three or more light sources is combined, the frequency component of the low frequency noise described above is It occurs between the lights with the smallest wavelength difference Δλ. Therefore, when combining light emitted from three or more light sources, the above-described low-frequency noise is satisfied by satisfying the above equation 6 between the lights having the smallest wavelength difference Δλ (frequency difference Δf). The problem can be solved.

Incidentally, actually, when selecting the wavelength lambda ₁ to [lambda] _N of for example N number of light sources based on the above equation 6, as the wavelength lambda in the above formula 6, the wavelength of the plurality of light lambda ₁ to [lambda] _N May be used, or any one of the wavelengths λ _{1 to} λ _N of a plurality of lights may be used. As described above, since the wavelengths λ _{1 to} λ _N are close values under the assumption of Δf << f, the average value λm of the wavelengths λ _{1 to} λ _N of the plurality of lights and the wavelength λ of each light _There is no significant difference from the value of _k (k = 1 to N). Therefore, as for the wavelength λ in the above equation 6, no significant difference appears in the calculated frequency difference Δf regardless of which of the two is used. That is, in the present invention, the wavelengths (frequency) of a plurality of (for example, N) light sources may be selected based on the following equation instead of the above equation 6.

[Configuration of heat-assisted magnetic recording device]
Next, the configuration of the heat-assisted magnetic recording device (information recording device) according to the first embodiment of the invention will be described. FIG. 5 shows a schematic configuration example of the configuration of the thermally-assisted magnetic recording apparatus according to the present embodiment. In the present embodiment, the configuration of a thermally assisted magnetic recording apparatus that records and / or reproduces information by irradiating a recording medium with minute light such as near-field light from a thermally assisted magnetic head will be described.

  The heat-assisted magnetic recording apparatus 100 includes a flying slider 101, a suspension 102 that supports the flying slider 101, a head actuator 103 that drives the flying slider 101, and a spindle 104. The recording medium 300 (information recording medium) is fixed to the rotating shaft 105 of the spindle 104 and is driven to rotate.

  The recording medium 300 is a disk-shaped medium and is a recording medium capable of recording information by a perpendicular magnetic recording method or an in-plane magnetic recording method. Although not shown in FIG. 5, the recording medium 300 includes a substrate 301 and a magnetic recording layer 302 formed on the substrate 301 (see FIGS. 7 and 8 to be described later). Then, the recording medium 300 is mounted on the spindle 104 so that the magnetic recording layer 302 faces the lower surface of the flying slider 101. In addition, a lubricant and a protective film are appropriately formed on the surface of the recording medium 300 to have a thin thickness in order to prevent damage due to contact between the flying slider 101 and the recording medium 300 during operation of the heat-assisted magnetic recording apparatus 100.

  FIG. 6 shows an enlarged side view of the vicinity of the flying slider 101 of the heat-assisted magnetic recording apparatus 100 of the present embodiment. The flying slider 101 includes a slider body 106 and a heat-assisted magnetic head 110 mounted at the tip of the slider body 106. The slider body 106 is disposed in close proximity to the recording medium 300 when the heat-assisted magnetic recording apparatus 100 is in operation. At this time, the heat-assisted magnetic head 110 is also disposed so as to face the recording medium 300. The configuration of the heat-assisted magnetic head 110 will be described in detail later.

  In the present embodiment, the heat-assisted magnetic recording apparatus 100 has been described by taking a recording / reproducing apparatus capable of recording and / or reproducing information as an example, but the present invention is not limited to this. The present invention can be similarly applied to a recording apparatus dedicated to recording, and similar effects can be obtained.

  Furthermore, in the present embodiment, the slider type heat-assisted magnetic recording apparatus 100 has been described, but the present invention is not limited to this. The present invention can be similarly applied to a heat-assisted magnetic recording apparatus of a type in which the distance between the heat-assisted magnetic head and the recording medium is controlled by an actuator, and similar effects can be obtained.

[Configuration of heat-assisted magnetic head]
Next, the configuration of the heat-assisted magnetic head 110 of this embodiment will be described. FIG. 7 shows a schematic cross-sectional view of the vicinity of the heat-assisted magnetic head 110 of the heat-assisted magnetic recording apparatus 100. FIG. 7 is a cross-sectional view in the direction along the moving direction of the recording medium 300.

  In the present embodiment, the heat-assisted magnetic head 110 is formed on an air outflow side surface S2 (hereinafter referred to as a trailing surface S2) perpendicular to the surface S1 of the slider body 106 facing the recording medium 300. The light source 190 is mounted via an electrode pad 180 provided on a surface S4 opposite to the trailing surface S2 of the heat-assisted magnetic head 110 (hereinafter referred to as a tip surface S4). In the present embodiment, a configuration example in which four lights having different wavelengths (wavelengths λ1 to λ4) are emitted from the light source 190 to the thermally-assisted magnetic head 110 will be described.

In addition, four concave portions 51 are formed in an array on the surface of an insulating portion 50 (to be described later) that constitutes the distal end surface S4 of the thermally assisted magnetic head 110, and the bottom of each concave portion 51 is predetermined with respect to the distal end surface S4. It is inclined at an angle. In the present embodiment, the light source 190 has a front end surface of the heat-assisted magnetic head 110 such that four mesas (light emitting units), which will be described later, of the light source 190 (VCSEL chip) and four corresponding recesses 51 face each other. Implemented in S4. With this implement source 190, light emitted from each mesa optical path is changed by the prism effect of the bottom of the corresponding recess 51, is obliquely incident on the condenser portion of the recording light generator 4 0, which will be described later. The configuration of the light source 190 will be described in detail later.

  The heat-assisted magnetic head 110 includes a magnetic reproducing element 10, a magnetic shield 20, a recording magnetic field generating unit 30, and a recording light generating unit 40 (light beam emitting unit). Each part is formed by being laminated on the trailing surface S2 of the slider body 106 via the insulating part 50. As a method for forming each part, for example, a conventional photolithography technique applied to a semiconductor element manufacturing process or the like can be used. The insulating part 50 is formed of an insulating material having light transparency, and is appropriately selected depending on required optical characteristics (for example, refractive index).

  The magnetic reproducing element 10 detects a magnetic field leaking from the recording magnetic domain of the magnetic recording layer 302. The magnetic reproducing element 10 is disposed between the magnetic shield 20 and a return yoke 32 (to be described later) of the recording magnetic field generating unit 30, and is disposed so that its detection surface faces the recording medium 300. As the magnetic reproducing element 10, for example, a magnetoresistive effect element such as a GMR (Giant Magneto Resistance) element or a TMR (Tunnel Magneto Resistance) element can be used. In the heat-assisted magnetic recording apparatus 100 of this embodiment, information is reproduced based on the signal detected by the magnetic reproducing element 10.

  The magnetic shield 20 is formed on the trailing surface S <b> 2 of the slider body 106 via the insulating unit 50. The magnetic shield 20 can be formed of the same material as that of the conventional heat-assisted magnetic head.

  The recording magnetic field generation unit 30 includes a recording magnetic pole part 31, a return yoke 32, a connection magnetic pole part 33, and an excitation coil 34 wound around the connection magnetic pole part 33. In the present embodiment, a current is passed through the excitation coil 34 to generate a recording magnetic field from the tip of the recording magnetic pole portion 31 and apply the recording magnetic field to a predetermined area of the recording medium 300.

  The recording magnetic pole portion 31 is a magnetic pole that generates a recording magnetic field from the tip, and is composed of a rod-shaped magnetic body that extends in parallel with the trailing surface S2 of the slider body 106. In the present embodiment, the cross-sectional shape orthogonal to the extending direction of the recording magnetic pole portion 31 is a square. In addition, the recording magnetic pole portion 31 is bent toward the trailing surface S2 in the middle of its extension, and the cross-sectional shape in the direction along the extending direction is substantially S-shaped.

  The thickness of the magnetic pole part (the magnetic pole part before bending) in the region connected to the connecting magnetic pole part 33 of the recording magnetic pole part 31 (the magnetic pole thickness in the direction orthogonal to the trailing surface S2) is the value after bending. It is made thicker than the thickness of the magnetic pole part in the region. Furthermore, the width of the magnetic pole part in the region after the recording magnetic pole part 31 is bent becomes narrower toward the tip. Note that the configuration (for example, the shape and dimensions) of the recording magnetic pole portion 31 is not limited to the example shown in FIG. 7, and can be appropriately changed according to, for example, the required magnetic field strength and application.

  Further, in order to realize high-density recording on the recording medium 300 by the heat-assisted magnetic recording method, it is necessary to apply a recording magnetic field immediately after (or simultaneously with) heating a predetermined region of the magnetic recording layer 302 with light. There is. Therefore, the tip of the recording magnetic pole part 31 (the end opposite to the connection magnetic pole part side) is disposed in the vicinity of the light emitting part 43 described later of the recording light generating part 40.

  The return yoke 32 is a magnetic pole for returning the magnetic field lines (magnetic flux) of the recording magnetic field generated at the tip of the recording magnetic pole portion 31 to the trailing surface S 2 side of the slider body 106. While the current flows through the exciting coil 34, the magnetic field lines are looped and closed between the return yoke 32 and the recording magnetic pole portion 31 via the connecting magnetic pole portion 33, and the return yoke 32 and the recording magnetic pole portion 31 are closed. Is a magnetically (physically) connected state. Thereby, the intensity of the recording magnetic field at the tip of the recording magnetic pole part 31 can be further increased. In order to generate a stronger recording magnetic field, it is preferable to bring the tip of the recording magnetic pole portion 31 closer to the return yoke 32. For these reasons, it is preferable to arrange a light emitting portion 43 (to be described later) of the recording light generating portion 40 between the recording magnetic pole portion 31 and the return yoke 32 as in this embodiment.

  In the present embodiment, since the magnetic reproducing element 10 is disposed between the return yoke 32 and the magnetic shield 20 as described above, the return yoke 32 is also used as a magnetic shield. Therefore, in this embodiment, the configuration (shape and size) of the return yoke 32 is the same as that of the magnetic shield 20. However, the configuration of the return yoke 32 is not limited to the example shown in FIG. 7, and can be changed as appropriate according to the arrangement position of the magnetic reproducing element 10, for example.

  The connecting magnetic pole portion 33 is a rod-shaped magnetic pole connecting the recording magnetic pole portion 31 and the return yoke 32. In the present embodiment, the shape of the cross section orthogonal to the extending direction of the connecting magnetic pole portion 33 is a square. Note that the configuration (for example, shape and size) of the connecting magnetic pole portion 33 can be changed as appropriate according to, for example, the required magnetic field strength and application. Further, while a current is flowing through the exciting coil 34, a magnetic path is generated in the connecting magnetic pole portion 33 from the recording magnetic pole portion 31 toward the return yoke 32 or in the opposite direction.

  Note that the magnetic material similar to the magnetic pole used in the conventional heat-assisted magnetic head or magnetic head can be used as the material for forming the recording magnetic pole part 31, the return yoke 32 and the connecting magnetic pole part 33. For example, a magnetic material such as NiFe or CoFeNi can be used as a material for forming the recording magnetic pole part 31, the return yoke 32, and the connection magnetic pole part 33.

  Next, the configuration of the recording light generator 40 will be described with reference to FIGS. FIG. 8 is a schematic front view of the recording light generator 40 viewed from the light source 190 side.

  The recording light generating unit 40 includes four light collecting units 41 a to 41 d, four single mode waveguides 42 a to 42 d (combining units) connected to them, and a light emitting unit 43.

  The four light converging parts 41a to 41d receive the emitted lights 191 to 194 from the light source 190, respectively, and guide the received lights to the corresponding single mode waveguides 42a to 42d, respectively. At this time, in the present embodiment, the received light is condensed in each of the four light collecting portions 41a to 41d, and the collected light is guided to the corresponding single mode waveguide. That is, in this embodiment, each of the four light condensing units 41a to 41d performs the optical path conversion operation and the light condensing operation on the corresponding incident light at the same time.

  In the present embodiment, as shown in FIG. 8, the incident positions of the four incident lights 191 to 194 are different. Therefore, the arrangement positions of the four light collecting portions 41 a to 41 d and the four single mode waveguides 42 a to 42 d The extended lengths are also different from each other.

  In the present embodiment, in order to perform an optical path conversion operation of incident light, a grating coupler in which a concavo-convex pattern (periodic structure) having a predetermined period is formed on the surface on the incident light side is used as a condensing part. FIG. 9 shows an example of the configuration. In addition, FIG. 9 shows only the structure of the condensing part 41c among the four condensing parts 41a-41d. The other light collecting portions 41a, 41b, and 41d have the same configuration as the light collecting portion 41c. Therefore, here, the configuration of only the light collecting unit 41c will be described.

  In the present embodiment, a grating coupler whose incident surface has a fan shape is used as the light collecting portion 41c. Then, an end (light exit port) on the apex angle side of the light collecting portion 41c is connected to the single mode waveguide 42c.

  In the present embodiment, in order to realize high-efficiency optical coupling in the condensing part 41c, the period of the concavo-convex pattern (the concave part 45 and the convex part 46) is appropriately set with respect to the wavefront of the incident light 193. Further, in order to efficiently collect the light received by the concavo-convex pattern, the concavo-convex pattern is concentric with the connection portion on the single mode waveguide 42c side of the condensing part 41c, and the width of the light receiving surface of the condensing part 41c Is narrowed linearly toward the connecting portion on the single mode waveguide 42c side. The condensing part 41c is formed of a light transmissive material having a higher refractive index than the insulating part 50 formed around the condensing part 41c.

  However, the configuration of the concavity and convexity pattern of the condensing part 41c (for example, the period, the height of the convex part 46, etc.) is, for example, the wavelength of the incident light 193 (propagating light), the incident angle of the incident light 193 to the condensing part 41c, It is set as appropriate in consideration of the material for forming the condensing part 41c, the material for forming the surrounding insulating part 50, and the like.

  The four single mode waveguides 42 a to 42 d propagate the light guided from the corresponding four light collecting portions 41 a to 41 d to the light emitting portion 43. The propagation mode of light propagating in each single mode waveguide (optical waveguide) is one (single mode), and the shape and dimensions of each single mode waveguide are set so that the propagation light is single mode. Is done. In this way, by setting the propagation light in the optical waveguide to a single mode, the wavefront of the propagation light can be stabilized without depending on the propagation distance, and recording light having stable intensity characteristics can be introduced into the light emitting portion 43. it can. As a result, the light emitting unit 43 can be driven stably, and the recording medium 300 can be irradiated with light with little fluctuation in intensity. Each single mode waveguide is formed of a light transmissive material having a refractive index higher than that of the insulating portion 50 formed around the single mode waveguide, like the light collecting portion 41c.

  In this embodiment, since the propagation mode in each single mode waveguide is set to a single mode, the shape and size of the cross section orthogonal to the extending direction of each single mode waveguide are the extension of each single mode waveguide. Constant along the direction. In addition, the shape of the cross section orthogonal to the extending direction of each single mode waveguide can be any shape as long as the light can propagate in the single mode. For example, the cross-sectional shape of each single mode waveguide can be set to, for example, a circle, a square, a trapezoid, or the like. Further, the dimensions of the cross section of each single mode waveguide are appropriately set according to, for example, the formation material of the optical waveguide, the formation material of the peripheral member (cladding material) of the optical waveguide, the wavelength of light to be propagated, and the like.

  Further, as shown in FIG. 8, each single mode waveguide is formed by being bent into a substantially L shape so as to bypass the connection magnetic pole portion 33 of the recording magnetic field generation unit 30 (not shown). And the edge part by the side of the light emission surface S3 of the four single mode waveguides 42a-42d is connected in the light emission part 43 vicinity. When the optical waveguide is formed so as to bypass the connecting magnetic pole portion 33 as in the present embodiment, the connecting magnetic pole portion 33 is not heated by the propagating light, so that deterioration of the magnetic characteristics of the entire magnetic pole is suppressed. Can do.

  In the single mode waveguide, light can be propagated with no loss or low loss even if the optical path is bent within a predetermined curvature range. Therefore, even if the optical waveguide is bent so as to bypass the connecting magnetic pole portion 33 in the middle of the extension of each single mode waveguide as in this embodiment, if the curvature is within a predetermined range, there is no loss. Alternatively, light can be propagated with low loss. The curvature range is determined by the refractive index difference between the optical waveguide and the surrounding material (insulating portion 50).

  In the present embodiment, the extension length (optical path length) of each single mode waveguide is appropriately set depending on the configuration of the light emitting unit 43. For example, when the polarization direction of the introduced light required by the light emitting unit 43 is a direction parallel to the light emitting surface S3, when the plurality of propagating lights are combined in the vicinity of the light emitting unit 43, the same The extension length of each single mode waveguide is set so as to be multiplexed in phase. On the other hand, when the polarization direction of the introduced light required by the light emitting unit 43 is a direction orthogonal to the light emitting surface S3, the reverse is applied when a plurality of propagating lights are combined in the vicinity of the light emitting unit 43. The extension length of each single mode waveguide is set so as to be multiplexed in phase.

  The configuration of each single mode waveguide is not limited to the example shown in FIG. 8. For example, the incident position of a plurality of incident lights, the arrangement position of the connecting magnetic pole part 33 of the recording magnetic field generating unit 30, and the light emitting part 43 It can be appropriately changed according to the arrangement position. Further, for example, the optical waveguide may be configured by a multimode waveguide as long as light having sufficiently stable intensity can be introduced into the light emitting unit 43. For example, when the optical waveguide can be made relatively short, it is relatively easy to design a multimode waveguide that can introduce light having stable intensity into the light emitting portion 43. Therefore, in such a case, even if the optical waveguide is constituted by a multimode waveguide, the same effect as that obtained when the single mode waveguide is used can be obtained. Further, in the present embodiment, each light condensing unit may be configured such that light collected by the light converging unit is directly introduced into the light emitting unit 43 without providing an optical waveguide.

  Next, a configuration example of the light emitting unit 43 will be described with reference to FIG. FIG. 10 is a schematic perspective view of the vicinity of the light emitting portion 43 viewed from the light emitting surface S3 side. In the present embodiment, when information is recorded on the recording medium 300, heat assist recording is performed using minute light such as near-field light, for example. Therefore, in this embodiment, a surface plasmon generating element capable of emitting such minute light is used as the light emitting unit 43.

  The light emitting portion 43 is a pair of metal films disposed at a predetermined distance from each other in the direction along the polarization direction A3 of the combined light 160 of the four propagating lights introduced through the four single mode waveguides 42a to 42d. It is comprised by 43a and 43b (metal structure). The interval between the pair of metal films 43a and 43b is set to the size of the required shortest recording mark. When the surface plasmon generating element configured as described above is irradiated with the combined light 160 (propagating light) having the polarization direction A3 in the same direction as the facing direction between the pair of metal films 43a and 43b, the pair of metal films 43a and 43b Surface plasmons are generated on the facing surface of 43b. As a result, minute light 170 having a diameter of about the distance between the pair of metal films 43 a and 43 b is emitted, and the minute light 170 is irradiated onto a predetermined area of the recording medium 300.

  Further, in the present embodiment, in order to generate a surface plasmon resonance phenomenon at the end surface on the light incident side of each metal film, a convex portion and a concave portion are formed on the end surface at a predetermined cycle along the polarization direction A3 of the multiplexed light 160. An uneven pattern arranged alternately is formed. With such a configuration, surface plasmons are generated not only on the facing surface between the pair of metal films 43a and 43b but also on the side surfaces between the concave and convex portions, and these surface plasmons are generated in the periodic direction (polarized light) of the concave / convex pattern. Propagate in direction A3) and overlap each other in phase. As a result, the intensity of the surface plasmon generated on the opposing surface between the pair of metal films 43a and 43b is increased, and the high-intensity minute light 170 can be emitted from between the pair of metal films 43a and 43b.

  The configuration of the light emitting portion 43 (surface plasmon generating element) is not limited to the configuration shown in FIG. 10, and surface plasmon is generated on the end face of the metal film when the combined light 160 having the polarization direction A3 is irradiated. If it is the structure to do, it can be set as arbitrary structures. For example, the light emitting portion 43 may be configured by only one metal film of the pair of metal films 43a and 43b. Moreover, in this embodiment, as the light emission part 43, if it is a light emission part which can generate | occur | produce minute lights, such as near-field light, for example, the light emission part of arbitrary structures can be used.

  Further, when a surface plasmon generating element is used as the light emitting portion 43, in order to improve the efficiency of the light emitting portion 43, for example, the vicinity of the light emission exits of the four single mode waveguides 42a to 42d is formed into a taper shape. It may be processed or a lens-like structure may be provided.

[Configuration of light source]
As a generation source of the plurality of lights emitted to the heat-assisted magnetic head 110, a plurality of light sources may be used, or a light source configured to emit a plurality of lights with one light source may be used. An example of the latter is a VCSEL chip in which a plurality of mesas are arranged on the same substrate. It is easy to manufacture a plurality of mesas including a laser light emitting layer on the same substrate. In this embodiment, a VCSEL chip in which four mesas are arranged on the same substrate is used as the light source 190.

  FIG. 11 shows a schematic configuration of a light source 190 used in the heat-assisted magnetic recording apparatus 100 of the present embodiment. The light source 190 includes a substrate 195, four disk-shaped convex portions 196a to 196d (base portions), and four mesas 190a to 190d (including a light emitting layer).

  The four disk-like convex portions 196a to 196d are formed on the substrate 195 and arranged in an array at positions corresponding to the arrangement of the four concave portions 51 formed on the front end surface S4 of the heat-assisted magnetic head 110. The four mesas 190a to 190d are formed on the four disk-shaped convex portions 196a to 196d, respectively. The light emitting layers of the four mesas 190a to 190d emit light 191 to 194 having wavelengths λ1 to λ4, respectively.

  In the present embodiment, the wavelengths λ1 to λ4 (frequency f1) of the light 191 to 194 emitted from the four mesas 190a to 190d are changed by changing the diameters of the four disk-shaped convex portions 196a to 196d in the surface of the substrate 195. To change f4). The reason why the wavelength of the emitted light from the light emitting layer of each mesa can be changed with such a configuration is as follows.

  Each light emitting layer is formed on the corresponding disk-shaped convex part by a technique such as MOCVD. In this case, the gradient of the raw material concentration in the vapor phase during crystal growth in the surface of the substrate 195 varies depending on the shape of the uneven pattern on the substrate 195. That is, by changing the diameter of the disk-shaped convex part that becomes the base of the light-emitting layer, the gradient of the raw material concentration on the disk-shaped convex part can be changed, and as a result, the light emitted from the formed light-emitting layer The wavelength of can also be changed. Therefore, as in this embodiment, by changing all the diameters of the four disk-shaped convex portions 196a to 196d, the wavelengths λ1 to λ1 of the light 191 to 194 emitted from the light emitting layers of the four mesas 190a to 190d, respectively. λ4 can be different from each other.

  In addition, the wavelength of the light inject | emitted from a light emitting layer becomes long, so that the diameter of a disk-shaped convex part becomes small. Therefore, in the example shown in FIG. 11, a relationship of λ1 <λ2 <λ3 <λ4 is established between the wavelengths λ1 to λ4 of the four lights 191 to 194.

  In the present embodiment, the relationship of the above formula 6 or 7 exists between the minimum frequency difference Δf (minimum wavelength difference Δλ) between the four lights 191 to 194 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300. The diameter of each disc-shaped convex portion (the wavelength of the emitted light from each light emitting layer) is appropriately set so as to be established.

  The polarization direction of the light emitted from each light emitting layer is appropriately set according to the configuration of the light emitting unit 43 that emits minute light.

  Specifically, for example, when the light emitting unit 43 is configured by the surface plasmon generating element shown in FIG. 10, the deflection directions of the four lights 191 to 194 are changed in the incident surface of each condensing unit of the single mode waveguide. Match the direction perpendicular to the extending direction (thick arrow in FIG. 8). Further, for example, when the facing direction of the pair of metal films of the light emitting portion 43 is the short direction of the light emitting surface S3 in FIG. 10, the deflection directions of the four incident lights 191 to 194 correspond respectively. In the incident surface of the light condensing unit, the direction is matched with the extending direction of the single mode waveguide. The polarization direction of the light emitted from the light emitting layer can be adjusted by, for example, etching the periphery of the light emitting port of the light emitting layer into a predetermined shape and applying a stress in the predetermined direction to the light emitting port.

  In the example shown in FIG. 11, the example in which the convex portion is provided on the substrate and the light emitting layer (mesa) is formed thereon is described, but the present invention is not limited to this. A recess may be provided on the substrate, and the light emitting layer may be formed in the recess by a technique such as MOCVD. Even in this case, the wavelength of light emitted from the light emitting layer can be changed by changing the dimension of the recess in the substrate surface direction, specifically, the opening width of the recess. Furthermore, both the convex portion and the concave portion may be provided on the substrate, and the light emitting layer may be formed on those regions by a technique such as MOCVD.

  Further, in the configuration of the recording light generation unit 40 of the present embodiment, the optical path of each propagation light from each condensing unit to the light emission unit 43 is different, and the incident angles of a plurality of propagation lights introduced into the light emission unit 43 are also included. Different from each other. In this case, for example, the light intensity distribution in the in-plane direction of the light exit surface S3 is also different for each propagating light, so that it is difficult to stably and efficiently introduce the combined light having the desired light intensity distribution into the light exit unit 43. There is also a fear. Therefore, when such a problem occurs, the emission intensity of each light emitted from the light source 190 is changed so that the intensity distributions of the plurality of propagation lights introduced into the light emitting unit 43 are the same. It is preferable to adjust.

[Operation of heat-assisted magnetic recording device]
In the heat-assisted magnetic recording apparatus 100 of the present embodiment, the four light beams 191 to 194 emitted from the light source 190 (VCSEL chip) to the heat-assisted magnetic head 110 are changed in optical path by four light converging units 41a to 41d, respectively. Focused. The lights collected by the four light collecting portions 41a to 41d are introduced into the corresponding single mode waveguides.

  The propagating light introduced into each single mode waveguide propagates through each single mode waveguide, and is multiplexed in the vicinity of the light emitting portion 43, and the combined light is incident on the light emitting portion 43. The light emitting unit 43 generates minute light such as near-field light from the incident combined light, and emits the minute light to a predetermined area of the recording medium 300.

  In the heat-assisted magnetic recording apparatus 100 according to the present embodiment, as described above, the minimum frequency difference Δf between the four lights 191 to 194 incident on the four light converging units 41 a to 41 d and the shortest recording length of the recording medium 300 are obtained. The relationship of the above formula 6 or 7 is established with the recording frequency fm corresponding to. That is, in the present embodiment, the frequency (= Δf) of the low frequency noise generated when the four lights 191 to 194 are combined is greater than the recording frequency fm corresponding to the shortest recording length.

  Therefore, when the thermally assisted magnetic recording is performed on the recording medium 300 using the thermally assisted magnetic recording apparatus 100 of the present embodiment, the above-described problem of erroneous recording due to the influence of low frequency noise can be solved. Therefore, according to the present embodiment, the recording medium 300 can be stably irradiated with higher intensity recording light, and the reliability of the apparatus can be further improved.

<2. Various modifications of the thermally-assisted magnetic recording apparatus of the first embodiment>
Next, various modifications of the heat-assisted magnetic recording apparatus 100 of the first embodiment described above will be described. In the following various modifications, only the configuration different from the heat-assisted magnetic recording apparatus 100 of the first embodiment will be mainly described. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals.

[Modification 1]
In the first embodiment, the example in which the four light beams 191 to 194 emitted from the light source 190 are received by the four light collecting units 41a to 41d provided separately has been described. It is not limited. For example, the four light beams 191 to 194 may be received by one light collecting unit. In Modification 1, one configuration example will be described.

  FIG. 12 shows a schematic configuration of the light collecting unit used in the heat-assisted magnetic head of the first modification. In this example, the condensing part 60 is comprised with the grating coupler whose incident surface is fan shape. Then, the end of the light collecting unit 60 on the apex angle side is connected to the single mode waveguide 63.

  In this example, since the four light beams 191 to 194 are received by one light collecting unit 60, only one single mode waveguide 63 is provided. Although not shown, the single mode waveguide 63 is formed so as to bypass the connection magnetic pole portion 33 of the recording magnetic field generation unit 30 as in the first embodiment. Note that the shape and dimensions of the single mode waveguide 63 are set so that the light propagating inside the waveguide becomes a single mode.

  In this example, in order to realize high-efficiency optical coupling at the condensing unit 60, four incident lights 191 to 194 are incident on the incident surface of the condensing unit 60, as in the first embodiment. The period of the concavo-convex pattern (concave part 61 and convex part 62) is appropriately set with respect to the wavefront. In this example, in order to efficiently collect the light received by the concavo-convex pattern, the concavo-convex pattern is concentric with respect to the connection portion on the single mode waveguide 63 side of the condensing unit 60, and The width of the light receiving surface is linearly narrowed toward the connection portion on the single mode waveguide 63 side.

  In addition, the condensing part 60 can be formed with the same material as the four condensing parts 41a-41d demonstrated in the said 1st Embodiment. Further, the configuration of the concave / convex pattern of the light collecting unit 60 (for example, the period, the height of the convex portion 62, etc.) includes, for example, the wavelength of incident light, the incident angle of incident light to the light collecting unit 60, It is set as appropriate in consideration of the material and the material for forming the insulating portion 50 around the light collecting portion 60.

  The condensing unit 60 of this example condenses the received four lights 191 to 194 by changing the optical path. At this time, the condensing unit 60 further combines the received four lights 191 to 194 and introduces the combined light into the single mode waveguide 63. That is, in this example, the condensing unit 60 simultaneously performs an optical path changing operation, a condensing operation, and a combining operation on the received light.

  In addition, when using the condensing part 60 of this example, and the light-projection part 43 shown in FIG. 10, the polarization direction of each light which injects into the condensing part 60 is each of the uneven | corrugated pattern of the condensing part 60, respectively. It is preferable to match the direction perpendicular to the periodic direction (thick arrow in FIG. 12). In this case, the polarization direction of the light combined near the inlet of the single mode waveguide 63 is in the same plane as the light receiving surface of the condensing unit 60 and orthogonal to the light propagation direction. Can be matched. In addition, when it is necessary to match the polarization direction of the combined light with the direction orthogonal to the light receiving surface of the condensing unit 60 and orthogonal to the light propagation direction due to the configuration of the light emitting unit 43, the condensing unit The polarization direction of each light incident on 60 is matched with the periodic direction of the concavo-convex pattern of the condenser 60.

  Also in this example, between the minimum frequency difference Δf between the four lights 191 to 194 incident on the light collecting unit 60 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300, the above formula 6 or 7 By satisfying this relationship, the same effect as in the first embodiment can be obtained.

[Modification 2]
In the first embodiment, the example in which the light collecting unit and the optical waveguide are separately provided for each of the plurality of lights incident on the heat-assisted magnetic head has been described, but the present invention is not limited thereto, For example, a plurality of light collecting portions and optical waveguides may be provided integrally. In the second modification, one configuration example will be described.

  FIG. 13 shows a schematic configuration of a recording light generation unit in the heat-assisted magnetic head of Modification 2. FIG. 13 is a schematic plan view on the light receiving surface side of the recording light generating unit of this example. In the example shown in FIG. 13, an example in which the recording light generation unit receives three lights is shown. However, the present invention is not limited to this, and the number of received lights depends on, for example, the required light intensity. Can be changed as appropriate.

The recording light generation unit 70 in this example includes a planar waveguide unit 73, grating couplers 74 a to 74 c, and a light emission unit 72. In addition, the light emission part 72 can be set as the structure similar to the light emission part 43 (for example, FIG. 10) of the said 1st Embodiment. Therefore, description of the light emission part 72 is abbreviate | omitted here.

The recording light generation unit 70 mainly includes a planar waveguide unit 73 (combining unit) and three grating couplers 74a to 74c (condensing units) formed on the light receiving surface.

  The planar waveguide portion 73 is a substantially trapezoidal plate-like member, and its upper side and lower side are linear, and the length of the upper side is longer than the length of the lower side. Moreover, the side part which connects between the upper side and lower side of the planar waveguide part 73 is a curve which becomes convex outward, and it is with respect to the direction (longitudinal direction) which goes to the lower side from the upper side of the planar waveguide part 73. It has a symmetrical shape. Then, the light emitting part 72 is arranged in the center of the lower side of the planar waveguide part 73. The planar waveguide portion 73 is formed of the same material as that of the single mode waveguide of the first embodiment.

  In the example shown in FIG. 13, the three grating couplers 74 a to 74 c are arranged at equal intervals on the central axis AX in the longitudinal direction of the planar waveguide portion 73. In this example, the three grating couplers 74a to 74c have the same configuration.

  In each grating coupler, two concavo-convex patterns (periodic structure) having a predetermined period have a symmetrical shape with respect to the central axis AX of the planar waveguide portion 73. Moreover, each concavo-convex pattern is formed such that the periodic direction of each concavo-convex pattern is symmetrically inclined at a predetermined angle with respect to the central axis AX. In this example, each concavo-convex pattern has an arc shape in order to give each grating coupler a condensing function. The periodic direction of each concavo-convex pattern is adjusted so that the light received by each concavo-convex pattern is reflected by the side surface of the planar waveguide portion 73 and introduced into the light emitting portion 72.

  However, in this example, the two concavo-convex patterns in each grating coupler are formed so as to be symmetric with respect to the central axis AX of the planar waveguide portion 73, but the present invention is not limited to this. The two concavo-convex patterns in each grating coupler can be appropriately changed according to the polarization direction of the combined light required when the combined light is introduced into the light emitting portion 72. For example, when the polarization direction of the combined light needs to be a direction orthogonal to the central axis AX, the two uneven patterns are formed to be symmetric with respect to the central axis AX as in this example. Further, for example, when it is necessary to make the polarization direction of the combined light in a direction along the central axis AX, one concavo-convex pattern may be formed with a half-cycle shift along the central axis AX with respect to the other concavo-convex pattern. Good.

  In the recording light generation unit 70 having the above-described configuration, for example, the light 251 incident on the grating coupler 74a has two propagation lights (broken lines in FIG. 13) along the periodic direction of the two concavo-convex patterns in the grating coupler 74a. Is demultiplexed. Each split propagation light is reflected by the side surface of the planar waveguide portion 73 and introduced into the light emitting portion 72. Lights 252 and 253 respectively incident on the other grating couplers 74 b and 74 c are also reflected by the side surface of the planar waveguide portion 73 and introduced into the light emitting portion 72 in the same manner as the incident light 251.

  In this example, the three grating couplers 74a to 74c have the same configuration and are arranged at equal intervals on the central axis AX of the planar waveguide portion 73. Therefore, the light emitting portions 72 from the three grating couplers 74a to 74c. The optical paths of the three propagating lights introduced into are different from each other. That is, in the configuration of the recording light generation unit 70 of this example, the incident angles of the three propagation lights introduced from the three grating couplers 74a to 74c into the light emission unit 72 are different from each other. Therefore, in this example, in order to stably and efficiently introduce the combined light having a desired light intensity distribution into the light emitting unit 72, the light emitting unit 72 changes the light emission intensity of each light emitted from the light source. It is preferable to adjust so that the intensity distribution of the plurality of lights introduced to the same is the same.

  Also in this example, between the minimum frequency difference Δf between the three incident lights 251 to 253 to the recording light generation unit 70 and the recording frequency fm corresponding to the shortest recording length of the recording medium, By satisfying the relationship of 7, the same effect as the first embodiment can be obtained.

[Modification 3]
When the condensing part is configured by a grating coupler as in the heat-assisted magnetic head 110 of the first embodiment, it is preferable that the region of the concave / convex pattern on the light receiving surface is not made larger than the spot diameter of incident light. This is due to the following reason. The grating coupler has a property of receiving light from the outside, but also has a property of radiating light propagating inside to the outside. Therefore, if the concave / convex pattern area on the light-receiving surface is too larger than the spot diameter of the incident light, the light received from the outside is emitted to the outside in the concave / convex pattern area while propagating through the grating coupler, and the optical coupling of the grating coupler The rate drops.

  Further, when a VCSEL having a stable output wavefront, that is, a so-called single mode VCSEL, is used as the light source, the following problems occur due to the properties of the grating coupler described above. The spot diameter of the emitted light from the single mode VCSEL is very small, about 10 μm or less. Therefore, when a grating coupler is used as the light collecting portion, it is necessary to reduce the size of the grating coupler. In this case, it is necessary to further improve the dimensional accuracy and mounting accuracy of the concave / convex pattern of the grating coupler, and it becomes more difficult to manufacture the grating coupler and the heat-assisted magnetic head.

  In Modification 3, an example of a heat-assisted magnetic recording apparatus that can solve the above-described problem will be described. FIG. 14 shows a schematic configuration in the vicinity of the light source in the heat-assisted magnetic recording apparatus of Modification 3. In FIG. 14, the same components as those in the embodiment (FIG. 7) are denoted by the same reference numerals. Further, in FIG. 14, only the configuration near the mesa 190a (the mesa that emits light having the wavelength λ1) among the four mesas 190a to 190d provided in the light source 190 is shown for the sake of simplicity.

  In this example, in order to solve the above problem, the spot diameter of light emitted from the mesa 190a is enlarged between the mesa 190a of the light source 190 and the heat-assisted magnetic head 110 (not shown in FIG. 14). The optical system 80 is provided. In this example, an optical system having the same configuration as that of the optical system 80 is provided for each of the other three mesas 190b to 190d.

  The optical system 80 includes a beam expander 81 and a prism 82. The beam expander 81 and the prism 82 are arranged in this order from the light source 190 side. In this example, in order to suppress the spread of light between the light source 190 and the optical system 80, the optical system 80 is provided in contact with the light emitting surface of the light source 190 as shown in FIG. However, the present invention is not limited to this, and a gap may be provided between the optical system 80 and the light exit surface of the light source 190, for example, according to the required light magnification factor.

  The beam expander 81 expands the spot diameter of the light 191 incident from the mesa 190a to a predetermined spot diameter, converts the expanded light into parallel light, and emits it.

  The prism 82 changes the direction of the parallel light emitted from the beam expander 81 to a predetermined direction. Specifically, in the prism 82, parallel light emitted from the beam expander 81 is obliquely incident at a predetermined angle on a condensing unit 41a (not shown in FIG. 14) made of a grating coupler in the recording light generation unit 40. Thus, the direction of the parallel light is changed.

  By providing the optical system 80 configured as described above between the mesa 190a of the light source 190 and the heat-assisted magnetic head 110 (not shown in FIG. 14), the expanded light 191EX is collected in the recording light generation unit 40. It can enter into the optical part 41a (grating coupler). In this case, the dimensions of the grating coupler and its concavo-convex pattern can be increased, and the manufacturing of the grating coupler and the heat-assisted magnetic head becomes easier.

  Further, also in this example, the relationship of the above formula 6 or 7 is satisfied between the minimum frequency difference Δf between the four lights emitted from the light source 190 and the recording frequency fm corresponding to the shortest recording length of the recording medium. By doing so, the same effect as the first embodiment can be obtained.

  In this example, the example in which the prism 82 is used in order to make the parallel light emitted from the beam expander 81 obliquely incident on the condensing unit 41a has been described. However, the present invention is not limited to this. For example, as in the heat-assisted magnetic head 110 (FIG. 7) of the first embodiment, when the concave portion 51 that performs the prism function is provided at the light incident position from the light source 190 on the tip surface S4 of the insulating portion 50. May not be provided with the prism 82. In addition, an incident light generation unit including the light source 190 and the optical system 80 is obliquely mounted at a predetermined angle with respect to the front end surface S4 of the heat-assisted magnetic head 110, and the light from the light source 190 is condensed by a grating coupler. May be incident obliquely. Also in this case, the prism 82 may not be provided in the optical system 80.

[Modification 4]
As described in the first embodiment and the second modification, when the incident angles of the plurality of propagating lights introduced into the light emitting unit in the recording light generating unit are different from each other, combined light having a desired light intensity distribution is obtained. There is a possibility that it is difficult to stably and efficiently introduce it into the light emitting portion. In the configurations of the first embodiment and the second modification, in order to solve this problem, the emission intensity of each light emitted from the light source may be adjusted. However, the method for solving the above problem is not limited to this method, and in Modification 4, a configuration example that can solve the above problem by another method will be described.

  FIG. 15 shows a schematic configuration in the vicinity of the light source in the heat-assisted magnetic recording apparatus of Modification 4. In this example, as shown in FIG. 15, light of wavelengths λ1 to λ3 (a broken line, a solid line, and an alternate long and short dash line in FIG. 15) is emitted from three light emitting units (mesas) 250 a to 250 c as light sources 250. Use VCSEL chip. Note that the number of mesas mounted on the VCSEL chip is not limited to this example, and can be appropriately changed according to, for example, the required light intensity.

  In this example, an optical system 85 is provided between the light source 250 and a heat-assisted magnetic head (not shown in FIG. 15) for expanding and multiplexing the three lights emitted from the light source 250.

  The optical system 85 includes a mirror unit 86, an enlarged light generation unit 87, a collimator lens 88, and a prism 89. The mirror unit 86, the enlarged light generation unit 87, the collimating lens 88, and the prism 89 are arranged in this order from the light source 250 side. In this example, in order to suppress the spread of light between the light source 250 and the optical system 85, the optical system 85 is provided in contact with the light emitting surface of the light source 250 as shown in FIG. However, the present invention is not limited to this, and a gap may be provided between the optical system 85 and the light exit surface of the light source 250, for example, depending on the required light magnification ratio.

  The mirror part 86 is formed of a light transmissive material, and four reflection mirrors 86a to 86d are provided therein. The reflection mirror 86a is disposed at a position facing the light exit surface of the mesa 250a, and the reflection mirror 86d is disposed at a position facing the light exit surface of the mesa 250c. The reflection mirrors 86b and 86c are disposed in the vicinity of the position facing the light emitting surface of the mesa 250b, and are disposed on the reflecting mirror 86a side and the reflecting mirror 86d side from the position facing the light emitting surface of the mesa 250b, respectively. The angles of the four reflection mirrors 86a to 86d are adjusted so that the emission directions of the three lights emitted from the mirror part 86 to the enlarged light generation part 87 are substantially parallel.

  When the four reflection mirrors 86a to 86d are arranged as described above, the light having the wavelength λ1 emitted from the mesa 250a (broken line in FIG. 15) is reflected by the reflection mirrors 86a and 86b and enters the enlarged light generation unit 87. Is done. On the other hand, the light having the wavelength λ3 emitted from the mesa 250c (the one-dot chain line in FIG. 15) is reflected by the reflection mirrors 86d and 86c and enters the enlarged light generation unit 87. Further, the light of wavelength λ2 emitted from the mesa 250b (solid line in FIG. 15) travels straight without being changed in the optical path and is incident on the enlarged light generation unit 87. In other words, the mirror unit 86 decreases the output pitch between the three lights emitted from the light source 250 and emits the three lights to the enlarged light generation unit 87.

  In this example, in order to prevent the diameters of the three lights propagating in the mirror part 86 from spreading during the propagation, it is preferable that the optical path of each propagating light has a waveguide structure. In this example, as will be described later, the three lights emitted from the mirror unit 86 are combined by the enlarged light generation unit 87. Therefore, in this example, the interval between the reflecting mirrors 86b and 86c arranged across the optical path of the light having the wavelength λ2 emitted from the mesa 250b is made as narrow as possible, and the output pitch between the three outgoing lights is made as small as possible. It is preferable (for example, about several μm or less).

  The enlarged light generator 87 is made of a light transmissive material, for example, a material similar to a conventional lens material. The magnified light generation unit 87 expands the spot diameter of the three lights incident from the mirror unit 86 to a predetermined size and multiplexes the three lights. Specifically, the spot diameter of each light incident from the mirror part 86 is spread by a diffraction phenomenon in the enlarged light generation part 87, and thereby the three lights are multiplexed. Then, the enlarged light generation unit 87 emits the combined and enlarged light to the collimator lens 88. Note that the configuration (for example, the forming material and the thickness) of the magnified light generation unit 87 is appropriately set according to, for example, the required light magnification ratio and the configuration of the light collecting unit.

  The collimator lens 88 converts the combined light that has been enlarged to a predetermined spot diameter by the enlarged light generation unit 87 into parallel light, and emits the parallel light to the prism 89.

  The prism 89 changes the direction of the parallel light emitted from the collimating lens 88 to a predetermined direction. Specifically, the prism 89 causes the parallel light emitted from the collimator lens 88 to be incident obliquely at a predetermined angle on a condensing unit (not shown) made of a grating coupler in a recording light generation unit (not shown). The direction of the parallel light is changed.

  In the configuration of this example, a plurality of lights are combined, and the combined light is introduced into the recording light generation section of the thermally assisted magnetic head. It is only necessary to provide one optical waveguide leading to the part.

  Here, an example of the magnification factor of light in the optical system 85 configured as described above will be briefly described. For example, consider a case where the refractive index of the magnified light generation unit 87 is 1.45, the thickness of the light propagation direction of the magnified light generation unit 87 is 300 μm, and the wavelength of incident light is 850 nm. In this case, when light having a spot diameter of about 3 μm is incident on the light incident surface of the magnified light generator 87, the optical system 85 having the above configuration sets the diameter of parallel light on the light exit surface of the collimator lens 88 to about 75 μm (enlarged). (Ratio: about 25 times).

  When the optical system 85 configured as described above is used, a plurality of lights are combined and the combined light is introduced into the recording light generation unit of the heat-assisted magnetic head. Can be the same (common). Therefore, the incident angles of a plurality of lights introduced into the light emitting part are the same, and the above-described problems can be solved, and the combined light having a desired light intensity distribution can be stably and efficiently applied to the light emitting part. Can be introduced.

  In this example, a plurality of lights emitted from the light source 250 are enlarged and introduced into the heat-assisted magnetic head. Therefore, in this example, as in the second modification, the dimensions of the grating coupler and its concavo-convex pattern can be increased, and the manufacturing of the grating coupler and the heat-assisted magnetic head can be facilitated.

  Further, in this example, between the minimum frequency difference Δf between the three lights respectively emitted from the three mesas 250a to 250c and the recording frequency fm corresponding to the shortest recording length of the recording medium, the above formula 6 or 7 Satisfy the relationship. Therefore, also in this example, the same effect as the first embodiment can be obtained.

  In this example, the example in which the prism 89 is used to obliquely enter the parallel light emitted from the collimator lens 88 into the light collecting unit (not shown) of the recording light generation unit has been described. It is not limited. For example, as in the heat-assisted magnetic head 110 (FIG. 7) of the first embodiment, when the concave portion 51 that performs the prism function is provided at the light incident position from the light source 190 on the tip surface S4 of the insulating portion 50. May not be provided with the prism 89. In addition, an incident light generation unit including the light source 250 and the optical system 85 is obliquely mounted at a predetermined angle with respect to the front end surface S4 of the heat-assisted magnetic head, and the light from the light source 250 is applied to the condensing unit including a grating coupler. It may be incident obliquely. Also in this case, the prism 89 may not be provided in the optical system 85.

[Modification 5]
In the first embodiment, the example in which the four light collecting portions 41a to 41d are configured by grating couplers has been described, but the present invention is not limited to this. A condensing unit having an arbitrary configuration can be used as long as both light path conversion and condensing operations can be performed on light incident from the light source 190. Modification 2 shows an example of the configuration.

  FIG. 16 shows a schematic configuration of a recording light generator used in the heat-assisted magnetic head of the fifth modification. In FIG. 16, the same components as those of the recording light generator 40 (FIG. 8) of the first embodiment are denoted by the same reference numerals.

  The recording light generation unit 90 of Modification 5 includes four metal films 91a to 91d, four single mode waveguides 42a to 42d connected to them, and a light emission unit 43, respectively. That is, in this example, in the recording light generation unit 40 (FIG. 8) of the first embodiment, each light condensing unit is configured using a metal film instead of the grating coupler.

  FIG. 17 shows a schematic configuration in the vicinity of the light collecting portion made of a metal film. FIG. 17 shows only the configuration in the vicinity of the metal film 91c among the four metal films 91a to 91d. Other configurations in the vicinity of the metal film are the same as those in the vicinity of the metal film 91c. Therefore, here, only the configuration of the metal film 91c will be described.

  In this example, the metal film 91c (mirror structure) is a metal film having a rectangular surface, the width is wider than the width of the corresponding single mode waveguide 42c, and the thickness is the same as that of the single mode waveguide 42c. Same as thickness. Then, the size of the surface of the metal film 91c on the light receiving side of the light 193 is made smaller than the size of the surface on the opposite side to the light receiving side, and the end surface 92c of the metal film 91c on the single mode waveguide 42c side is made into a taper shape. . In order to suppress a decrease in light guiding efficiency to the single mode waveguide 42c, both the thickness and width of the metal film 91c are preferably equal to or greater than those of the single mode waveguide 42c.

  By using the metal film 91c having such a configuration, a mirror part 93c (reflection mirror) is defined at the interface between the metal film 91c and the single mode waveguide 42c. When the light 193 from the light source 190 is introduced into the mirror part 93c, the light is reflected by the mirror part 93c and guided to the single mode waveguide 42c. At this time, for example, a condensing lens is disposed between the light source 190 and the recording light generation unit 90, and the spot size of the light 193 introduced into the mirror unit 93c is suitable for the size of the single mode waveguide 42c. It is preferable to narrow down to a different size. In this case, the light reflected by the mirror part 93c can be efficiently introduced into the single mode waveguide 42c.

  As described above, also in the light collecting unit made of the metal film of this example, both the optical path conversion and the light collecting operations can be performed on the light incident from the light source 190 as in the first embodiment. .

  Also in this example, between the minimum frequency difference Δf between the four lights 191 to 194 incident on the recording light generator 90 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300, the above formula 6 or By satisfying the relationship of 7, the same effect as the first embodiment can be obtained.

[Modification 6]
In the above-described modification 5, the example in which the four light beams 191 to 194 emitted from the light source 190 are received by the condensing unit including the four metal films 91a to 91d provided separately has been described. It is not limited to this. For example, you may receive four light 191-194 with the condensing part which consists of one metal film. In Modification 6, one configuration example will be described.

  In FIG. 18, the schematic structure of the condensing part of the modification 6 is shown. The condensing unit 95 in this example includes a metal film 96 and a condensing waveguide 98 that connects the metal film 96 and the single mode waveguide 99. In this example, as in the first modification, the four light beams 191 to 194 are received by the single condensing unit 95, so that only one single mode waveguide 99 is provided. The condensing waveguide 98 is formed of the same material as the single mode waveguide 99.

  The metal film 96 is a metal film having a substantially rectangular surface, and the end surface 97 on the condensing waveguide 98 side has a taper shape and is an arc-shaped curved surface with respect to the optical entrance of the single mode waveguide 99. Formed with. In this example, four lights 191 to 194 are incident at predetermined intervals along the arc-shaped end surface 97 of the metal film 96 on the condensing waveguide 98 side. In this example, the formation positions of the four mesas 190a to 190d in the light source 190 are appropriately changed according to the incident positions of the four lights 191 to 194.

  In the configuration of this example, the end surface 97 of the metal film 96 on the condensing waveguide 98 side functions as a mirror portion (reflection mirror). When the four light beams 191 to 194 are introduced from the light source 190 to the end face 97, the lights are reflected by the end face 97 and introduced into the condensing waveguide 98. Then, the introduced four lights are condensed and combined in the condensing waveguide 98, and the combined light is guided to the single mode waveguide 99.

  As described above, the light condensing unit 95 in this example can simultaneously perform optical path conversion, light condensing, and multiplexing operations on the light incident from the light source 190.

  Also in this example, between the minimum frequency difference Δf between the four lights 191 to 194 incident on the light condensing unit 95 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300, the above formula 6 or 7 By satisfying this relationship, the same effect as in the first embodiment can be obtained.

<3. Second Embodiment>
In the first embodiment and various modifications, the example in which the light source 190 is provided on the front end surface S4 (end surface on the air outflow side) of the heat-assisted magnetic head 110 has been described, but the present invention is not limited to this. For example, the light source may be arranged in the same direction as the extending direction of the optical waveguide. In the second embodiment, an example of the configuration will be described.

[Configuration of heat-assisted magnetic head]
FIG. 19 shows a schematic configuration of a thermally-assisted magnetic head according to the second embodiment of the present invention. In FIG. 19, the same components as those of the heat-assisted magnetic head 110 (FIGS. 7 and 8) of the first embodiment are denoted by the same reference numerals.

  In the thermally-assisted magnetic head 200 of this embodiment, the configuration of the recording magnetic field generation unit is the same as that of the first embodiment (FIG. 7). Therefore, the configuration of the recording magnetic field generation unit is omitted in FIG. 19, and the description of the configuration of the recording magnetic field generation unit is also omitted in the following description.

  In the present embodiment, the heat-assisted magnetic head 200 is formed on the trailing surface S2 of the slider body 106. The light source 250 is mounted on the surface S5 of the thermally assisted magnetic head 200 on the side opposite to the recording medium 300 side.

  In the present embodiment, a VCSEL chip including three mesas 400a to 400c arranged on the same substrate surface is used as the light source 400. And three light 401-403 is each inject | emitted from the three mesa 400a-400c (light emission part) to the heat-assisted magnetic head 200. FIG. In the present embodiment, the three mesas 400a to 400c are arranged in a row in the direction along the trailing surface S2 and in the direction orthogonal to the extending direction of the optical waveguide 202 described later (y direction in FIG. 19). To do. Note that the mesas 400a to 400c are arranged at positions facing a first light collecting unit 211 described later.

  In the present embodiment, similarly to the light source 190 (FIG. 11) used in the first embodiment, the diameter of the disk-shaped convex portion (not shown) that serves as a base for forming each mesa is changed. The wavelength (frequency) of the light emitted from each of the three mesas 400a to 400c is changed.

  Specifically, in this embodiment, the diameter of each disk-shaped convex portion is set so that the relationship of λ1 <λ2 <λ3 is established between the wavelengths λ1 to λ3 of the light emitted from the three mesas 400a to 400c. Set. Further, in the present embodiment, the relationship of the above formula 6 or 7 is established between the minimum frequency difference Δf between the three lights 401 to 403 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300. Next, the diameter of each disk-shaped convex part is set.

  Next, the configuration of the recording light generating unit 210 (light beam emitting unit) of the present embodiment will be described.

  The recording light generating unit 210 includes a light collecting unit 201, an optical waveguide 202, and a light emitting unit 43. Each part is formed by being laminated on the trailing surface S2 of the slider body 106 via the insulating part 50. As a method for forming each part, for example, a conventional photolithography technique applied to a semiconductor element manufacturing process or the like can be used.

  The light collecting unit 201 includes a first light collecting unit 211 and a second light collecting unit 212. In the present embodiment, the first light collector 211 is disposed in the vicinity of the end surface S5 on the light incident side of the heat-assisted magnetic head 200. In addition, the second light collecting unit 212 is disposed at a position closer to the light emitting unit 43 of the heat-assisted magnetic head 200 than the first light collecting unit 211 via the insulating unit 50. Then, the second light condensing unit 212 is connected to the light emitting unit 43 side end and one end of the optical waveguide 202. In addition, the 1st condensing part 211, the 2nd condensing part 212, and the optical waveguide 202 are coaxially arrange | positioned in the propagation direction (z direction in FIG. 19) of light.

  The first light collecting unit 211 includes four refracting members 213 that are formed at a predetermined distance from each other in the direction orthogonal to the trailing surface S2 of the slider body 106 (the x direction in FIG. 19). Each refracting member 213 is a quadrangular columnar member extending in a direction along the trailing surface S2 and in a direction orthogonal to the extending direction of the optical waveguide 202 (y direction in FIG. 19). Each refractive member 213 is formed of a material having a higher refractive index than that of the insulating portion 50.

  As described above, in the present embodiment, the first condensing unit 211 is configured by the four refracting members 213 arranged in stripes in the direction orthogonal to the trailing surface S2 (the x direction in FIG. 19). With such a configuration, the first condensing unit 211 functions as a condensing lens similar to the Fresnel lens. As a result, the three light beams 401 to 403 incident on the first light collecting unit 211 from the light source 400 are orthogonal to the trailing surface S2 by the first light collecting unit 211 as indicated by an arrow L1 in FIG. The light is condensed in the direction (x direction in FIG. 19).

  In the first condensing unit 211, each light emitted from the light source 400 is appropriately adjusted by appropriately adjusting the configuration of each refractive member 213, such as the material, thickness, and width, and the distance between the refractive members 213. The spot diameter can be reduced at a predetermined rate. Further, in this example, the configuration of each refracting member 213 is configured so that the emitted light from the first light collector 211 can be efficiently condensed on the end surface 212a of the second light collector 212 on the first light collector 211 side. Set.

  In the example shown in FIG. 19, the end surfaces on the light source 400 side of the four refractive members 213 constituting the first light collector 211 are formed so as to be exposed on the light incident side end surface S <b> 5 of the heat-assisted magnetic head 200. However, the present invention is not limited to this. For example, if it is possible to introduce a sufficient amount of light from the light source 400 to the first light collecting unit 211, the end surface on the light source 400 side of the refractive member 213 is not exposed to the light incident side end surface S5. Good. In addition, when the 1st condensing part 211 is comprised so that the end surface by the side of the light source 400 of the refractive member 213 may be exposed to light incident side end surface S5 like this embodiment, the fall of light utilization efficiency is suppressed more. Can do.

  The second light collector 212 is a plate-like member having a constant thickness in a direction orthogonal to the trailing surface S2 (x direction in FIG. 19). The surface of the 2nd condensing part 212 is parallel to the trailing surface S2, and the shape is a substantially fan shape. Then, the end face (side face) on the apex angle side of the substantially fan-shaped surface of the second light collecting section 212 is connected to the optical waveguide 202, and the end face 212 a on the arcuate long side faces the first light collecting section 211. Be placed. The second light collector 212 is formed of the same material as the optical waveguide 202.

  When the second light collector 212 is configured as described above, the light incident on the arc-shaped end surface 212a of the second light collector 212 from the first light collector 211 is indicated by an arrow L2 in FIG. In the 2nd condensing part 212, it condenses in the direction (y direction in FIG. 19) orthogonal to the propagation direction of light. At this time, the three lights 401 to 403 are combined with the condensed light. Then, the second condensing unit 212 emits the light, which is condensed and combined in the direction orthogonal to the light propagation direction (the y direction in FIG. 19), into the optical waveguide 202.

  The optical waveguide 202 is formed to extend from the light exit surface of the second light collector 212 (the end surface on the apex angle side of the substantially fan-shaped surface) toward the medium facing surface (S1) of the heat-assisted magnetic head 200, A light emitting unit 43 is provided in the vicinity of the medium facing surface. In addition, the light emission part 43 can be set as the structure similar to the said 1st Embodiment (for example, the structure etc. which are shown in FIG. 10).

  In the present embodiment, the optical waveguide 202 is configured by a single mode waveguide, as in the first embodiment. The shape and dimensions of the optical waveguide 202 are set so that the light propagating inside becomes a single mode.

[Recording light generation operation]
Next, the recording light generation operation in the heat-assisted magnetic head 200 of this embodiment will be described with reference to FIGS. 20 (a) and 20 (b). FIG. 20A is a diagram illustrating the light condensing state of the recording light generating unit 210, and FIG. 20B is a diagram illustrating the change of the light spot in each condensing stage.

  First, three lights 251 to 253 having different wavelengths from the light source 250 are emitted to the first light collecting unit 211. Here, the spot shape of each light incident on the first light collecting portion 211 is circular as shown by a spot SP0 in FIG. In addition, the solid line arrow in FIG.20 (b) has shown the polarization direction of light. Here, since the structure shown in FIG. 10 is assumed as the light emitting portion 43, the polarization direction of light is set to the y direction (direction orthogonal to the light propagation direction) in FIG.

  Each light incident on the first light collecting unit 211 is collected in the first light collecting unit 211 in a direction perpendicular to the trailing surface S2 of the slider body 106 (x direction in FIG. 20A). . As a result, the spot shape of each light collected by the first light collecting unit 211 is an elliptical shape reduced in the x direction in FIG. 20B, as indicated by a spot SP1 in FIG. 20B. It becomes.

  And when each light condensed by the 1st condensing part 211 injects into the 2nd condensing part 212, the light will be orthogonal to the propagation direction of light inside the 2nd condensing part 212 The light is condensed in the y direction in FIG. At this time, the second light collecting unit 212 condenses and combines the three lights 401 to 403. As a result, the spot shape of the combined light L3 emitted from the second light collecting unit 212 to the optical waveguide 202 is further changed from the state of the spot SP1 to the spot SP1 as shown by the spot SP2 in FIG. In (b), it is reduced in the y direction and becomes a circle.

  As described above, in the recording light generation unit 210 of the present embodiment, the light incident from the light source 400 is subjected to a light collecting operation in a one-dimensional direction orthogonal to the propagation direction in two stages, and the incident light is predetermined. Focus on the spot size.

  Then, the light L <b> 3 (combined light) introduced from the second light collector 212 into the optical waveguide 202 propagates through the optical waveguide 202 and enters the light emitting unit 43. The light emitting unit 43 generates minute light such as near-field light from the incident combined light, and emits the minute light to a predetermined area of the recording medium 300.

  The polarization direction of each light emitted from the light source 400 is appropriately set according to the configuration of the light emitting unit 43 that emits minute light. For example, the light emitting portion 43 is configured by a pair of metal films 43a and 43b as in FIG. 10, and the opposing direction between the pair of metal films 43a and 43b is the short direction of the light emitting surface S3 (in FIG. x direction), the polarization direction of the light emitted from the light source 400 is also adjusted to that direction.

  As described above, also in this embodiment, between the minimum frequency difference Δf between the three lights 401 to 403 incident on the heat-assisted magnetic head 200 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300. In addition, the above-described expression 6 or 7 is established. That is, also in the present embodiment, the frequency (= Δf) of the low frequency noise generated when the three lights 401 to 403 are combined is larger than the recording frequency fm corresponding to the shortest recording length.

  Therefore, even when the heat-assisted magnetic recording is performed on the recording medium 300 using the heat-assisted magnetic recording apparatus of the present embodiment, the above-described problem of erroneous recording due to the influence of low frequency noise can be solved. Therefore, according to the present embodiment, similarly to the first embodiment, it is possible to stably irradiate the recording medium 300 with higher intensity recording light, and to further improve the reliability of the apparatus.

<4. Third Embodiment>
In the heat-assisted magnetic recording apparatus according to the first and second embodiments and various modifications, a plurality of light emitting units (for example, the light emitting layer in the above embodiment) provided in the light source to generate high output recording light. Etc.) is preferably the same. This operation can be realized, for example, by simultaneously driving the driving electrode terminals (electrode pads) of the light emitting units in common. In this case, the mounting area of the light source can be further reduced.

  However, even if the drive electrode terminals between the light emitting units are shared, if the equivalent resistance of each light emitting unit varies among the plurality of light emitting units, the current flowing through each light emitting unit also varies. The output may be different for each light emitting unit. In this case, there arises a problem that the lifetime changes for each light emitting unit, and a problem that the light intensity profile of the combined light differs for each light source. In the third embodiment, a configuration example of a light source that can solve such a problem is shown.

  FIG. 21 shows a schematic configuration of a light source used in the heat-assisted magnetic recording apparatus of this embodiment. The heat-assisted magnetic recording apparatus of this embodiment can be configured in the same manner as the heat-assisted magnetic recording apparatus described in the first embodiment (FIGS. 7 and 8) except for the configuration of the light source.

  The light source 500 of the present embodiment includes four light emitting units 501 to 504, a driver 505 that drives them, and four resistance adjusting elements 506 to 509. Also in this embodiment, the above formula is between the minimum frequency difference Δf between the four lights emitted from the four light emitting units 501 to 504 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300. The light source 500 is configured so that the relationship 6 or 7 is established.

  The four resistance adjusting elements 506 to 509 are connected in series to the four light emitting units 501 to 504, respectively. In the present embodiment, both drive electrode terminals 500a and 500b of each series circuit including the light emitting section and the resistance adjusting element are common. One drive electrode terminal 500 a is connected to one output terminal of the driver 505, and the other drive electrode terminal 500 b is connected to the other output terminal of the driver 505.

  Each resistance adjusting element is set so that the equivalent resistance of each series circuit including the light emitting section and the resistance adjusting element is equal in all the series circuits. For example, the resistance adjusting element can be configured by a wiring pattern or the like. In this case, the line width of the wiring pattern is appropriately adjusted for each resistance adjusting element by a technique such as laser ablation, so that the equivalent resistances of the four series circuits are made equal. Thereby, the above-described problem in the case where there is a variation in equivalent resistance among the plurality of light emitting units can be solved.

  Note that the configuration of the light source for eliminating variation in equivalent resistance among the plurality of light emitting units is not limited to the example shown in FIG. For example, a wiring pattern in which a small resistance element (component) can be inserted from the outside in the light source is formed, and if necessary, a small resistance element is inserted into the wiring pattern from the outside to include a light emitting unit. The equivalent resistance of the circuit system may be adjusted.

  In this example, the example in which the resistance adjusting element is provided on one driving power supply terminal side of the light emitting unit has been described. However, the present invention is not limited thereto, and the resistance adjustment is performed on the other driving power supply terminal side of the light emitting unit. An element may be provided, or a resistance adjusting element may be connected to each of the driving power supply terminals. Further, the resistance adjusting element may be connected in parallel to the light emitting unit.

  As described above, also in this embodiment, between the minimum frequency difference Δf between the four lights emitted from the light source 500 and the recording frequency fm corresponding to the shortest recording length of the recording medium 300, the above equation 6 or 7 is established.

  Therefore, even when the heat-assisted magnetic recording is performed on the recording medium 300 using the heat-assisted magnetic recording apparatus of the present embodiment, the above-described problem of erroneous recording due to the influence of low frequency noise can be solved. Therefore, according to the present embodiment, similarly to the first embodiment, it is possible to stably irradiate the recording medium 300 with higher intensity recording light, and to further improve the reliability of the apparatus.

  Furthermore, according to the present invention, it is possible to solve the above-mentioned problem caused by variations in equivalent resistance among a plurality of light emitting sections, and to provide a more reliable heat-assisted magnetic recording apparatus.

  In the light sources of the first to third embodiments and various modified examples, the example in which a plurality of mesas (light emitting unit: including a light emitting layer) are integrally formed on the same substrate has been described. It is not limited. For example, a light source may be configured by using a DFB laser that emits light having a long coherent length instead of VCSEL and forming a plurality of light emitting layers on the same substrate. Further, for example, a light source may be configured using a plurality of light emitting units prepared separately, and may be configured to emit light simultaneously.

  In the first to third embodiments and various modifications, the example in which the present invention is applied to the heat-assisted magnetic recording apparatus has been described. However, the present invention is not limited to this. Any optical device (light beam generation device) that combines a plurality of lights and performs predetermined processing using the combined light can be applied to any device, and the same effect can be obtained.

  For example, the present invention may be applied to a laser beam recording apparatus that records a desired image on a recording sheet with a laser beam as described in, for example, Patent Document 2 above. Further, for example, the present invention can also be applied to a laser beam processing machine that combines a plurality of laser beams, irradiates a predetermined object with the combined beams, and performs a processing process such as cutting. In such an application, the frequency corresponding to the shortest light emission time at the time of laser light emission control (processing control) corresponds to the shortest recording length described in the first to third embodiments and various modifications. Equivalent to fm.

  Therefore, in the above-described application, the optical device (light beam generation device) combines a light source composed of a plurality of (for example, N) light emitting units and a plurality of lights emitted from the light source, and combines them. And a light beam emitting unit for emitting a light beam. Then, the frequency (wavelength) of each light so that the relationship of the above expression 6 or 7 is established between the minimum frequency difference Δf between the plurality of lights to be combined and the frequency (fm) corresponding to the shortest light emission time. ) Should be adjusted. Thereby, the influence of the low frequency noise which generate | occur | produces in the combined light mentioned above can be reduced, and the effect similar to the said 1st-3rd embodiment and various modifications is acquired.

  DESCRIPTION OF SYMBOLS 10 ... Magnetic reproducing element, 20 ... Magnetic shield, 30 ... Recording magnetic field production | generation part, 40, 210 ... Recording light production | generation part, 41a-41d ... Condensing part, 42a-42d ... Single mode waveguide, 43 ... Light emission part, DESCRIPTION OF SYMBOLS 50 ... Insulating part, 100 ... Thermally assisted magnetic recording apparatus, 101 ... Flying slider head, 106 ... Slider main body, 110 ... Thermally assisted magnetic head, 190, 400, 500 ... Light source, 190a-190d, 400a-400c ... Mesa, 191 194, 401 to 403 ... incident light, 201 ... condensing part, 202 ... optical waveguide, 211 ... first condensing part, 212 ... second condensing part, 300 ... recording medium, 501-504 ... light emitting part, 505 ... Drivers, 506 to 509 ... Resistance adjustment elements

Claims (18)

It has a plurality of light emitting portions that emit light having different frequencies, and the minimum frequency difference Δf between the plurality of lights respectively emitted from the plurality of light emitting portions is based on the recording frequency fm corresponding to the shortest recording length of the information recording medium. A large light source,
An information recording apparatus comprising: a thermally assisted magnetic head that thermally assisted magnetically records information on the information recording medium using the combined light of the plurality of lights emitted from the light source. When the minimum wavelength difference between the plurality of lights is Δλ, the average value of the wavelengths of the plurality of lights is λm, and the speed of light is c,
c × (Δλ / λm ² )> fm
The information recording apparatus according to claim 1, wherein the relationship is established. The heat-assisted magnetic head includes a plurality of condensing units that condense the plurality of lights, and a combining unit that combines the plurality of lights respectively emitted from the plurality of condensing units. The information recording device described in 1. The information recording apparatus according to claim 3, wherein the condensing unit is configured by a grating coupler in which a predetermined uneven pattern is formed on a light incident surface. The multiplexing unit has a plurality of optical waveguides for propagating a plurality of condensed light beams emitted from the plurality of condensing units, and the propagation light emission ports of the plurality of optical waveguides are connected to each other. The information recording apparatus according to claim 4. The information recording apparatus according to claim 5, wherein the optical waveguide is a single mode waveguide. The polarization directions of the plurality of lights emitted from the light source are respectively set to predetermined directions, and the lengths of the plurality of optical waveguides are such that the polarization directions of the combined lights are directed to the predetermined directions. The information recording apparatus according to claim 5, wherein the information recording apparatus is set as follows. The information recording apparatus according to claim 3, wherein the light collecting unit includes a mirror structure that reflects light incident from the light source in a predetermined direction and guides the light to the multiplexing unit. The heat-assisted magnetic head further receives the combined light, converts the received light into recording light having a smaller spot diameter, and emits the recording light to the information recording medium The information recording device according to claim 3, further comprising a body. The information recording apparatus according to claim 3, wherein the plurality of condensing units and the combining unit are integrally formed. The information recording apparatus according to claim 4, further comprising an optical system that is provided between the light source and the heat-assisted magnetic head and that enlarges the diameter of each light emitted from the light source. The information recording apparatus according to claim 11, wherein the optical system is provided for each of the light emitting units. The information recording apparatus according to claim 1, wherein the light emission timings of the plurality of light emitting units are the same. The information recording apparatus according to claim 13 , wherein driving power terminals of the plurality of light emitting units are common. The information recording apparatus according to claim 14 , wherein the light source further includes a resistance adjusting element for adjusting an equivalent resistance of a circuit system connected to the light emitting unit and including the light emitting unit. The information recording apparatus according to claim 14 , wherein the light source further includes a wiring pattern for mounting a resistance adjustment element for adjusting an equivalent resistance of a circuit system including the light emitting unit from the outside. The light source includes a substrate, and a plurality of base portions each including a convex portion and / or a concave portion formed on the substrate, wherein the convex portion and / or the concave portion have different in-plane direction dimensions of the substrate. The information recording device according to claim 1, further comprising: the plurality of light emitting units respectively formed on a base portion of the base. A light source having a plurality of light emitting units that emit light having different frequencies from each other, and a light source having a minimum frequency difference between the plurality of light emitted from the plurality of light emitting units greater than the frequency corresponding to the shortest light emission time;
A light beam generating apparatus comprising: a light beam emitting unit that multiplexes the plurality of lights emitted from the light source and emits the combined light beam.

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