JP3236208B2 - Semiconductor laser device and optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device having excellent linearity of current-light output characteristics suitable as a light source of an optical pickup device such as an optical disk, and an optical pickup device using the semiconductor laser device as a light source.

[0002]

2. Description of the Related Art As a light source of an optical pickup device such as an optical disk, a semiconductor laser device which generates single mode oscillation has been conventionally used. In this case, in order to reduce return light noise caused by the laser light emitted from the semiconductor laser device being reflected by the optical disk and then incident again on the end face of the semiconductor laser device, a high-frequency wave is applied to the semiconductor laser device during signal reproduction. In this method, the oscillation spectrum is made multimode by superimposing the current, the buffering property of the laser light is reduced, and the return light noise is reduced.

FIG. 18 shows a schematic configuration of a first conventional optical pickup device using the conventional semiconductor laser device as a light source. As shown in FIG. 18, the laser light output from the semiconductor laser 30A is
After being converted into parallel light by 1, the light passes through a beam splitter 32 and thereafter reaches an information recording surface of an optical disk 34 by an objective lens 33. The laser light reflected from the information recording surface of the optical disc 34 is changed in direction by the beam splitter 32, is condensed by the detection lens 35, and then passes through the hologram optical element 36, and the light intensity is changed by the light receiving element 37. Is detected. In FIG. 18, 3
Reference numeral 8 denotes a high-frequency superimposed circuit module for causing the semiconductor laser device 30A to perform multimode oscillation.

FIG. 19 shows a schematic configuration of a second conventional optical pickup device using the conventional semiconductor laser device as a light source. In FIG. 19, reference numeral 40A denotes a laser unit in which a conventional semiconductor laser device, a light receiving element and a hologram optical element are integrated, and a laser beam output from the semiconductor laser device constituting the laser unit 40A is a collimator lens 41. Then, the light is collimated by the objective lens 42 and focused on the information recording surface of the optical disk 43. After the laser beam reflected from the information recording surface of the optical disc 43 passes through the objective lens 42 and the collimator lens 41, the light intensity is detected by an optical element constituting the laser unit 40A. In FIG. 20, reference numeral 44 denotes a high-frequency superimposed circuit module, and reference numeral 45 denotes a shield member that shields a high frequency generated from the high-frequency superimposed circuit module 44.

Recently, as a method of reducing return optical noise without using high-frequency current superposition, a method has been proposed in which a self-excited oscillation phenomenon of a semiconductor laser is used and a semiconductor laser whose oscillation spectrum is made multimode is used. I have.

Hereinafter, a conventional semiconductor laser device that oscillates by itself will be described.

FIG. 20 shows a cross-sectional structure of a conventional semiconductor laser device which oscillates by itself as disclosed in JP-A-6-196810. As shown in FIG. 20, an n-type gallium arsenide (GaAs) is used. ), A first cladding layer 12 of n-type gallium aluminum arsenide (GaAlAs), a first saturable absorption layer 13 of n-type GaAlAs, a second cladding layer 14 of n-type GaAlAs, Active layer 1 made of undoped GaAlAs
5, the third cladding layer 16 made of p-type GaAlAs,
A second saturable absorption layer 17 of GaAlAs is formed sequentially. Further, the center portion of the second saturable absorption layer 17 is made of p-type GaAlAs and is made of 0.5 μm to 1 μm.
A ridge-shaped fourth cladding layer 18 having a height of m and a lower surface width of 4 μm and extending in a stripe shape is formed, and a thickness of 0.3 μm of p-type GaAs is formed on the fourth cladding layer 18.
m cap layers 19 are formed. On both sides of the fourth cladding layer 18 and the cap layer 19 on the second saturable absorption layer 17, a film thickness of 0.8 of n-type GaAs is formed.
A μm current block layer 20 is formed, and a 4 μm thick contact layer 21 made of p-type GaAs is formed on the current block layer 20 and the cap layer 19.

In the above conventional semiconductor laser device,
The current injected from the contact layer 21 is effectively confined in the ridge-shaped fourth cladding layer 18 extending in a stripe shape, and laser oscillation occurs in a region of the active layer 15 below the fourth cladding layer 18. In this case, since the current blocking layer 20 absorbs the laser light, the oscillated laser light is effectively confined in the fourth cladding layer 18. Also,
The band gap energy of the first and second saturable absorbing layers 13 and 17 is made substantially equal to the band gap energy of the active layer 15 so that the first and second saturable absorbing layers 13 and 17 are
The self-excited oscillation is performed by giving the saturable absorption effect 7 to the oscillation laser light.

[0009]

However, in the above-mentioned conventional semiconductor laser device, the current-light output characteristic has non-linearity at the time of low light output, and therefore, when used as a light source for an optical pickup device such as an optical disk. Has a serious problem in practice. That is, the optical output at the time of reading information from an optical disk or the like is preferably about 3 mW, but the optical output sharply increases to about 5 mW due to a slight increase in injection current after laser oscillation. There is a problem that it is difficult to keep the light output at a constant level.

As described above, an optical output of about 3 mW is preferable for reading information from an optical disk or the like, and an optical output of about 30 mW is preferable for writing information. However, the conventional semiconductor laser device is used as a light source. In an optical pickup device, it is difficult to use a conventional semiconductor laser device for an optical pickup device because linearity is not obtained in a current-light output characteristic within a range of an optical output of 3 mW to 30 mW.

In an optical pickup device for a rewritable optical disk, the NA (Numerical Aperture) on the laser side of the lens is set to a CD in order to increase the light use efficiency.
(Compact Disk) is designed to be larger than the NA, so that the effect of astigmatism easily occurs. For this reason, the difference between the value of the astigmatic difference at the time of reading with a light output of 3 mW and the value of the astigmatic difference at the time of writing with a light output of 30 mW becomes large. There is a problem that when condensed light cannot be narrowed down into a small spot. Therefore, an optical component for correcting the astigmatism is required. However, the optical component for correcting the astigmatism is a factor that hinders miniaturization and cost reduction of the optical pickup device. In order not to use an optical component for correcting astigmatism, it is necessary to suppress the astigmatism of the semiconductor laser device to 5 μm or less. In a conventional semiconductor laser device, the astigmatism is about 10 μm. Therefore, the use of optical components for correcting the astigmatic difference cannot be avoided.

In view of the above, it is an object of the present invention to provide a semiconductor laser device which can improve the non-linearity of the current-light output characteristics at the time of low light output and can easily control the magnitude of the light output even at the time of low light output. It is a second object of the present invention to provide an optical pickup device capable of performing stable reading and writing on an optical disk or the like and achieving downsizing.

[0013]

According to the present invention, self-oscillation occurs when the thickness of the light absorbing layer is set to 5 nm or more, and the thickness of the light absorbing layer is set to 1/5 or less of the active layer. It has been found that linearity can be obtained in the current-light output characteristic at the time of low light output, and the present invention has been made based on this finding.

According to a first aspect of the present invention, there is provided a semiconductor laser device comprising: a first light guide layer made of a first conductivity type semiconductor layer formed on a semiconductor substrate; An active layer made of a semiconductor layer is formed on the layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second conductive layer is formed on the second light guide layer. A light absorbing layer formed of a semiconductor layer of a second conductivity type and absorbing a laser beam oscillated from the active layer is formed; a stripe region of a semiconductor layer of a second conductivity type is formed at a central portion on the light absorbing layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light absorption layer, and a current block layer is formed on the stripe region and the current block layer. 2
A third light guide layer of a conductivity type is formed, and the film thickness of the light absorbing layer is set to 5 nm or more and 1/5 or less of the film thickness of the active layer. Between
When the value of the band gap wavelength difference is 4 nm or more and 10 nm or less
It has a certain configuration.

According to the first aspect of the present invention, since the thickness of the light absorbing layer is 5 nm or more, the saturable absorption effect of the light absorbing layer can be secured, so that self-pulsation can be generated.
Further, since the thickness of the light absorbing layer is set to be not more than one fifth of the thickness of the active layer, the light confinement coefficient of the light distribution in the active layer in the vertical direction is smaller than the light confinement coefficient in the light absorbing layer. Will also be large enough. Solution taken specifically by the invention of claim 2
In the step, a semiconductor laser device is placed on a semiconductor substrate on a first conductivity type.
A first light guide layer made of a semiconductor layer of
An active layer made of a semiconductor layer is formed on the light guide layer,
A second optical gas comprising a semiconductor layer of the second conductivity type is formed on the active layer.
A second conductive type layer on the second light guide layer.
Laser light comprising the above semiconductor layer and oscillating from the active layer.
A light absorbing layer for absorbing is formed, and the light absorbing layer
A stripe region made of a semiconductor layer of the second conductivity type at the center
Is formed, and the stripe is formed on the light absorbing layer.
An active layer comprising a semiconductor layer of the first conductivity type on both sides of the region;
Current block layer to absorb laser light oscillating from
Is formed on the stripe region and the current block layer.
A third light guide layer of two conductivity type is formed, and
The film thickness is not less than 5 nm and not less than one fifth of the film thickness of the active layer.
The active layer has a multiple quantum well structure.
It has a configuration that it has.

According to a third aspect of the present invention, in the first or second aspect, a total thickness of the second light guide layer and the light absorbing layer is set to 0.3 μm or less. It is.

According to the third aspect of the present invention, a stable refractive index guiding mechanism can be ensured, and the lateral light distribution is strongly confined in the current channel. The light absorption loss received in the region below the block layer can be reduced.

According to a fourth aspect of the present invention, in addition to the first or third aspect, a configuration in which the light absorption layer has a quantum well structure is added.

[0019]

According to a fifth aspect of the present invention, in the configuration of the first or third aspect , the light absorption layer has a quantum well structure.
The active layer adds a structure having a multiple quantum well structure.

According to a sixth aspect of the present invention, there is provided a semiconductor laser device comprising: a first light guide layer formed of a first conductivity type semiconductor layer formed on a semiconductor substrate; An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second conductive layer is formed in a central portion on the second light guide layer. Current blocking layer formed of a semiconductor layer of the first conductivity type on both sides of the stripe region on the second light guide layer and absorbing laser light oscillated from the active layer. Is formed, and a third light guide layer of a second conductivity type is formed on the stripe region and the current block layer, and the first light guide layer absorbs at least one laser beam oscillated from the active layer.
A light absorbing layer, wherein the thickness of the light absorbing layer is set to 5 nm or more and 1/5 or less of the thickness of the active layer.

According to the configuration of claim 6, since the thickness of the light absorbing layer is 5 nm or more, the saturable absorption effect of the light absorbing layer can be secured, so that self-pulsation can be generated.
Further, since the thickness of the light absorbing layer is set to be not more than one fifth of the thickness of the active layer, the light confinement coefficient of the light distribution in the active layer in the vertical direction is smaller than the light confinement coefficient in the light absorbing layer. Will also be large enough.

According to a seventh aspect of the present invention, in addition to the configuration of the sixth aspect, a configuration is provided in which the thickness of the second light guide layer is set to 0.3 μm or less.

According to the structure of the seventh aspect, a stable refractive index guiding mechanism can be ensured, and the confinement of the lateral light distribution in the current channel is enhanced. The light absorption loss received in the region below the block layer can be reduced.

According to an eighth aspect of the present invention, in addition to the configuration of the sixth or seventh aspect, a configuration in which the light absorption layer has a quantum well structure is added.

According to a ninth aspect of the present invention, in addition to the configuration of the sixth or seventh aspect, a configuration in which the active layer has a multiple quantum well structure is added.

According to a tenth aspect of the present invention, in addition to the configuration of the sixth or seventh aspect, the light absorbing layer has a quantum well structure and the active layer has a multiple quantum well structure. Is what you do.

According to another aspect of the present invention, a semiconductor laser device is provided in which a first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and the first light guide layer is formed on the first light guide layer. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a semiconductor of the second conductivity type is formed on the second light guide layer. A third light guide layer formed of a first conductive layer and transparent to laser light oscillated from the active layer; and a stripe region formed of a second conductive type semiconductor layer in a central portion on the third light guide layer. A current blocking layer formed of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the third light guide layer; No. on the block layer A fourth light guide layer made of a conductive semiconductor layer is formed, and the first light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer. The film thickness is set to 5 nm or more and 1/5 or less of the film thickness of the active layer.

According to the eleventh aspect, since the thickness of the light absorption layer is 5 nm or more, the saturable absorption effect of the light absorption layer can be secured, so that self-pulsation can be generated. Since the film thickness of the layer is set to 1/5 or less of the film thickness of the active layer, the light confinement coefficient in the vertical direction of the light distribution to the active layer is sufficiently larger than the light confinement coefficient to the light absorption layer. Become.

According to a twelfth aspect of the present invention, in addition to the configuration of the eleventh aspect, a configuration is provided in which the total film thickness of the second light guide layer and the third light guide layer is set to 0.3 μm or less. It is.

According to the twelfth aspect, a stable refractive index guiding mechanism can be ensured, and the lateral light distribution is more strongly confined in the current channel. The light absorption loss received in the region below the block layer can be reduced.

The invention of claim 13 is the invention of claim 11 or 12
The light absorbing layer has a quantum well structure and is added to the structure described above.

The invention of claim 14 is the invention of claim 11 or 12
The structure in which the active layer has a multiple quantum well structure is added to the above structure.

[0034] The invention of claim 15 is the invention of claim 11 or 12.
In the above structure, the light absorbing layer has a quantum well structure, and the active layer has a multiple quantum well structure.

According to another aspect of the present invention, a semiconductor laser device is provided in which a first light guide layer made of a first conductivity type semiconductor layer is formed on a semiconductor substrate, and the first light guide layer is formed on the first light guide layer. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second light guide layer is formed on a central portion of the second light guide layer.
A stripe region made of a conductive semiconductor layer is formed,
A current blocking layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the second light guide layer,
A third light guide layer of a second conductivity type is formed on the stripe region and the current block layer, and the second light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer. The thickness of the light absorption layer is set to 5 nm or more and 1/5 or less of the thickness of the active layer.

According to the sixteenth aspect, since the thickness of the light absorbing layer is 5 nm or more, the saturable absorption effect of the light absorbing layer can be secured, so that self-pulsation can be generated. Since the film thickness of the layer is set to 1/5 or less of the film thickness of the active layer, the light confinement coefficient in the vertical direction of the light distribution to the active layer is sufficiently larger than the light confinement coefficient to the light absorption layer. Become.

According to a seventeenth aspect of the present invention, in addition to the configuration of the sixteenth aspect, a configuration is provided in which the thickness of the second light guide layer including the light absorbing layer is set to 0.3 μm or less.

According to the seventeenth aspect, a stable refractive index guiding mechanism can be ensured, and the confinement of the lateral light distribution in the current channel is enhanced. The light absorption loss received in the region below the block layer can be reduced.

The invention of claim 18 is the invention of claim 16 or 17
The structure in which the light absorption layer has a quantum well structure is added to the structure described above.

The invention of claim 19 is the invention of claim 16 or 17.
The structure in which the active layer has a multiple quantum well structure is added to the above structure.

According to the twentieth aspect of the present invention, there is provided a method as set forth in claim 16 or 17
In the above structure, the light absorbing layer has a quantum well structure, and the active layer has a multiple quantum well structure.

According to a twenty-first aspect of the present invention, there is provided a semiconductor laser device comprising: a semiconductor substrate having a first light guide layer formed of a semiconductor layer of a first conductivity type formed on a semiconductor substrate; An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second light guide layer of the second conductivity type is formed on the second light guide layer. A third light guide layer formed of a semiconductor layer and transparent to laser light oscillated from the active layer, and a stripe region formed of a second conductivity type semiconductor layer at a central portion on the third light guide layer; Is formed on both sides of the stripe region on the third light guide layer, a current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed. On the current blocking layer A two-conductivity type third light guide layer is formed, and the second light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer. The thickness is set to 5 nm or more and 1/5 or less of the thickness of the active layer.

According to the twenty-first aspect, since the thickness of the light absorbing layer is 5 nm or more, the saturable absorption effect of the light absorbing layer can be ensured, so that self-pulsation can be generated. Since the film thickness of the layer is set to 1/5 or less of the film thickness of the active layer, the light confinement coefficient in the vertical direction of the light distribution to the active layer is sufficiently larger than the light confinement coefficient to the light absorption layer. Become.

According to a twenty-second aspect, in the structure of the twenty-first aspect, the second light guide layer including the light absorbing layer and the third
The total thickness of the light guide layer and the light guide layer is set to 0.3 μm or less.

According to the structure of the twenty-second aspect, a stable refractive index guiding mechanism can be ensured, and the confinement of the lateral light distribution in the current channel is enhanced. The light absorption loss received in the region below the block layer can be reduced.

The invention of claim 23 is the invention of claim 21 or 22
The structure in which the light absorption layer has a quantum well structure is added to the structure described above.

The invention of claim 24 is the invention of claim 21 or 22
The structure in which the active layer has a multiple quantum well structure is added to the above structure.

The twenty-fifth aspect of the present invention is the twenty-first or the twenty-second aspect.
In the above structure, the light absorbing layer has a quantum well structure, and the active layer has a multiple quantum well structure.

According to another aspect of the present invention, there is provided a semiconductor laser device comprising: a first light guide layer formed of a first conductivity type semiconductor layer formed on a semiconductor substrate; An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second light guide layer is formed on a central portion of the second light guide layer.
A stripe region made of a conductive semiconductor layer is formed,
A current blocking layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the second light guide layer,
A third light guide layer of a second conductivity type is formed on the stripe region and the current block layer, and the third light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer. The thickness of the light absorption layer is set to 5 nm or more and 1/5 or less of the thickness of the active layer.

According to the twenty-sixth aspect, since the thickness of the light absorbing layer is 5 nm or more, the saturable absorption effect of the light absorbing layer can be secured, so that self-pulsation can be generated. Since the film thickness of the layer is set to 1/5 or less of the film thickness of the active layer, the light confinement coefficient in the vertical direction of the light distribution to the active layer is sufficiently larger than the light confinement coefficient to the light absorption layer. Become.

According to a twenty-seventh aspect of the present invention, in addition to the configuration of the twenty-sixth aspect, a configuration is provided in which the thickness of the second light guide layer is set to 0.3 μm or less.

According to the structure of the twenty-seventh aspect, a stable refractive index guiding mechanism can be secured, and the confinement of the light distribution in the lateral direction in the current channel is enhanced. The light absorption loss received in the region below the block layer can be reduced.

The invention of claim 28 is the invention of claim 26 or 27.
The structure in which the light absorption layer has a quantum well structure is added to the structure described above.

The invention of claim 29 is the invention of claim 26 or 27.
The structure in which the active layer has a multiple quantum well structure is added to the above structure.

The invention of claim 30 is the invention of claim 26 or 27.
In the above structure, the light absorbing layer has a quantum well structure, and the active layer has a multiple quantum well structure.

According to a thirty-first aspect of the present invention, there is provided a semiconductor laser device, comprising: a first light guide layer made of a semiconductor layer of a first conductivity type formed on a semiconductor substrate; An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a semiconductor of the second conductivity type is formed on the second light guide layer. A third light guide layer formed of a first conductive layer and transparent to laser light oscillated from the active layer; and a stripe region formed of a second conductive type semiconductor layer in a central portion on the third light guide layer. A current blocking layer formed of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the third light guide layer; No. on the block layer A fourth light guide layer made of a conductive semiconductor layer is formed, and the fourth light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer. The film thickness is set to 5 nm or more and 1/5 or less of the film thickness of the active layer.

According to the structure of claim 31, since the thickness of the light absorbing layer is 5 nm or more, the saturable absorption effect of the light absorbing layer can be ensured, so that self-pulsation can be generated. Since the film thickness of the layer is set to 1/5 or less of the film thickness of the active layer, the light confinement coefficient in the vertical direction of the light distribution to the active layer is sufficiently larger than the light confinement coefficient to the light absorption layer. Become.

According to a thirty-second aspect of the present invention, in addition to the structure of the thirty-first aspect, a configuration is provided in which the total thickness of the second light guide layer and the third light guide layer is set to 0.3 μm or less. It is.

According to the structure of the thirty-second aspect, a stable refractive index guiding mechanism can be ensured, and the lateral light distribution is strongly confined in the current channel. The light absorption loss received in the region below the block layer can be reduced.

The invention of claim 33 is the invention of claim 31 or 32.
The structure in which the light absorption layer has a quantum well structure is added to the structure described above.

The invention of claim 34 is the invention of claim 31 or 32.
The structure in which the active layer has a multiple quantum well structure is added to the above structure.

The invention of claim 35 is the invention of claim 31 or 32.
In the above structure, the light absorbing layer has a quantum well structure, and the active layer has a multiple quantum well structure.

According to a thirty-sixth aspect of the present invention, there is provided an optical pickup device, wherein a first light guide layer made of a first conductivity type semiconductor layer is formed on a semiconductor substrate, and the first light guide layer is formed on the first light guide layer. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a semiconductor of the second conductivity type is formed on the second light guide layer. A light absorbing layer that absorbs laser light oscillated from the active layer, and a stripe region made of a second conductivity type semiconductor layer is formed at a central portion on the light absorbing layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region above
A third light guide layer of the second conductivity type is formed on the stripe region and the current block layer, and the thickness of the light absorption layer is set to 5 nm or more and 1/5 or less of the active layer. The total thickness of the second light guide layer and the light absorbing layer is set to 0.3 μm or less, and the light absorbing layer and the active
Band gap wavelength difference between the active layer and the conductive layer is 4 nm or more and 1
A semiconductor laser device having a diameter of 0 nm or less, a light collecting means for collecting a light beam emitted from the semiconductor laser device on an information recording surface, and a light detecting means for detecting a light beam reflected from the information recording surface. Is provided.

The invention according to claim 37 is a solution to an optical pickup device, wherein a first light guide layer made of a first conductivity type semiconductor layer is formed on a semiconductor substrate, and the first light guide layer is formed on the first light guide layer. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second conductive layer is formed in a central portion on the second light guide layer. Current blocking layer formed of a semiconductor layer of the first conductivity type on both sides of the stripe region on the second light guide layer and absorbing laser light oscillated from the active layer. Is formed, and a second layer is formed on the stripe region and the current block layer.
A third light guide layer of a conductivity type is formed, and the first light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer, and the thickness of the light absorption layer is 5n.
m and not more than 1/5 of the thickness of the active layer, and the thickness of the second light guide layer is set to be 0.3 μm or less. And a light detecting means for detecting a light beam reflected from the information recording surface.

In another aspect of the present invention, an optical pickup device is provided in which a first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and the first light guide layer is formed on the first light guide layer. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a semiconductor of the second conductivity type is formed on the second light guide layer. A third light guide layer formed of a first conductive layer and transparent to laser light oscillated from the active layer; and a stripe region formed of a second conductive type semiconductor layer in a central portion on the third light guide layer. A current blocking layer formed of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the third light guide layer; On the block layer A fourth light guide layer formed of a two-conductivity type semiconductor layer is formed, wherein the first light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer; Is set to 5 nm or more and 1/5 or less of the film thickness of the active layer, and the total film thickness of the second light guide layer and the third light guide layer is 0.3 μm.
m, a condensing means for condensing a light beam emitted from the semiconductor laser device on an information recording surface, and a light for detecting a light beam reflected from the information recording surface And a detecting means.

In a preferred embodiment of the present invention, an optical pickup device is provided in which a first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and the first light guide layer is formed on the first light guide layer. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second conductive layer is formed in a central portion on the second light guide layer. Current blocking layer formed of a semiconductor layer of the first conductivity type on both sides of the stripe region on the second light guide layer and absorbing laser light oscillated from the active layer. Is formed, and a second layer is formed on the stripe region and the current block layer.
A third light guide layer of conductivity type is formed, and the second light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer, and the light absorption layer has a thickness of 5n.
a semiconductor laser device, wherein the thickness of the second light guide layer including the light absorption layer is set to 0.3 μm or less;
A light beam emitted from the semiconductor laser device is focused on an information recording surface; and a light detecting device detects a light beam reflected from the information recording surface. is there.

According to another aspect of the present invention, there is provided an optical pickup device, wherein a first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second light guide layer of the second conductivity type is formed on the second light guide layer. A third light guide layer formed of a semiconductor layer and transparent to laser light oscillated from the active layer, and a stripe region formed of a second conductivity type semiconductor layer at a central portion on the third light guide layer; Is formed on both sides of the stripe region on the third light guide layer, a current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed. Above the current block layer A third light guide layer of a second conductivity type is formed, the second light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer, and a thickness of the light absorption layer. Is set to 5 nm or more and 1/5 or less of the film thickness of the active layer, and the total film thickness of the second light guide layer including the light absorbing layer and the third light guide layer is A semiconductor laser device set to 0.3 μm or less, a focusing means for focusing a light beam emitted from the semiconductor laser device on an information recording surface, and detecting a light beam reflected from the information recording surface And a light detecting means.

According to another aspect of the present invention, there is provided an optical pickup device comprising: a first light guide layer formed of a first conductivity type semiconductor layer formed on a semiconductor substrate; An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a second conductive layer is formed in a central portion on the second light guide layer. Current blocking layer formed of a semiconductor layer of the first conductivity type on both sides of the stripe region on the second light guide layer and absorbing laser light oscillated from the active layer. Is formed, and a second layer is formed on the stripe region and the current block layer.
A third light guide layer of a conductivity type is formed, and the third light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer, and the thickness of the light absorption layer is 5n.
m and not more than 1/5 of the thickness of the active layer, and the thickness of the second light guide layer is set to be 0.3 μm or less. And a light detecting means for detecting a light beam reflected from the information recording surface.

According to a second aspect of the present invention, there is provided an optical pickup device, wherein a first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate. An active layer made of a semiconductor layer is formed on the active layer, a second light guide layer made of a semiconductor layer of the second conductivity type is formed on the active layer, and a semiconductor of the second conductivity type is formed on the second light guide layer. A third light guide layer formed of a first conductive layer and transparent to laser light oscillated from the active layer; and a stripe region formed of a second conductive type semiconductor layer in a central portion on the third light guide layer. A current blocking layer formed of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the third light guide layer; On the block layer A fourth light guide layer made of a two-conductivity type semiconductor layer is formed, and the fourth light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer. Is set to 5 nm or more and 1/5 or less of the thickness of the active layer, and the total thickness of the second light guide layer and the third light guide layer is 0.3 μm or less. Semiconductor laser device, light collecting means for collecting a light beam emitted from the semiconductor laser device on an information recording surface, and light detecting means for detecting a light beam reflected from the information recording surface Are provided.

According to the constitutions of claims 36 to 42, the semiconductor laser device generates self-sustained pulsation, so that the high frequency superimposed circuit module conventionally required for reducing the noise of the semiconductor laser device becomes unnecessary. In addition, since the astigmatism of the semiconductor laser device is small, the value of the astigmatism at the time of light output of about 3 mW suitable for reading information from an optical disk or the like and the astigmatism at the time of light output of about 30 mW suitable for writing information. The difference from the value of the difference also becomes small. Further, linearity is obtained in the current-light output characteristics within the range of the light output of 3 mW to 30 mW.

[0071]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor laser device according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional structure of the semiconductor laser device according to the first embodiment. As shown in FIG. 1, an n-type G-type semiconductor substrate 101 is formed on an n-type GaAs semiconductor substrate 101.
0.5 μm thick buffer layer 102 made of aAs, n
First optical guide layer 103 of 2.0 μm in thickness made of Ga _0.5 Al _0.5 As, active layer 104 of 0.06 μm in thickness of Ga _0.85 Al _0.15 As, p-type Ga _0.5 Al
0.24 μm-thick second optical guide layer 1 made of _0.5 As
05 and a p-type Ga _0.86 Al _0.14 As
A light absorption layer 106 of 01 μm is sequentially formed. At the center on the light absorption layer 106, p-type Ga _0.5 Al
4 μm width for forming a current channel made of _0.5 As
An m-type stripe region 107 is formed, and a 1.0 μm-thick current blocking layer 108 made of n-type GaAs is formed on both sides of the stripe region 107 on the light absorption layer 106. Stripe area 107
On the current blocking layer 108, p-type Ga _0.5 A
2.0 μm thick third light guide layer 1 made of _0.5 As
A contact layer 110 made of p-type GaAs and having a thickness of 2.0 μm is formed on the third optical guide layer 109.

The current block layer 107 is made of GaAs that absorbs laser light oscillated from the lower part of the stripe region 107 in the active layer 104 in order to obtain stable single transverse mode oscillation. Since the current block layer 107 absorbs the laser beam, the peak of the light intensity distribution below the current block layer 107 is pushed to the first light guide layer 103 side, that is, the semiconductor substrate 101 side. The effective refractive index of the light distribution decreases. For this reason, the effective refractive index of the light distribution below the stripe region 107 is higher than the effective refractive index of the light distribution below the current block layer 107, so that a refractive index guiding mechanism is obtained, and the light distribution becomes Stably trapped in the current channel.

The thickness of the light absorption layer 106 required for the semiconductor laser device to oscillate by itself will be described below.

When the film thickness of the light absorbing layer 106 is too small, the saturable absorption effect in the light absorbing layer 106 becomes small, so that self-excited oscillation does not occur. Therefore, in order to generate self-sustained pulsation without causing a large increase in the operating current value and to obtain a vertical distant field image with good symmetry, the light absorbing layer 1
The film thickness of 06 needs to be 5 nm or more. In the first embodiment, the thickness of the light absorption layer 106 is 10 nm.

Hereinafter, the oscillation spectrum characteristics and the bandgap wavelength difference Δλ (the bandgap wavelength of the light absorbing layer 106-the active layer 10
The relationship between the forbidden band width of No. 4) and the thickness of the light absorbing layer 106 will be described.

FIG. 2 shows that the second light guide layer 105 has a stable transverse transverse mode oscillation with a stable film thickness of 0.24 μm.
When the thickness of the active layer 104 is 0.06 μm, the dependence of the oscillation spectrum characteristic on the bandgap wavelength difference Δλ and the thickness of the light absorbing layer 106, and the nonlinearity in the current-light output characteristic The results of experiments with and without presence are shown.

The non-linearity in the current-light output characteristics is as follows.
As shown in FIG. 3, the linearity of the current-light output characteristic is degraded, and the light output sharply increases after laser oscillation. When the linearity of the current-light output characteristic is deteriorated, an APC (Automaton) for keeping the light output constant at a low light output required for reproducing information from the optical disk.
tic Power Control) driving becomes impossible, which causes a serious problem in practical use.

As shown in FIG. 2, the non-linearity of the current-light output characteristics occurs when the bandgap wavelength difference Δλ is larger than 10 nm and when the thickness of the light absorption layer 106 is larger than 12 nm. I understand. This is for the following reason. That is, the forbidden bandwidth wavelength difference Δλ is larger than 10 nm, or the thickness of the light absorption layer 106 is 12 nm.
If it becomes larger, the light absorption loss in the light absorption layer 106 increases, so that the amount of injection current necessary for laser oscillation increases. In this case, the injected carrier density of the active layer 104 also increases, but when the carrier density of the active layer 104 increases, the differential gain of the active layer 104 decreases, and when the current injection amount is increased, the guided light is increased. The rate at which the gain increases is also reduced. Further, the differential gain of the active layer 104 further decreases due to the heat generated by the semiconductor laser device due to the injection current. For this reason, it is necessary to further increase the amount of injected current in order to cause laser oscillation. As a result, the differential gain of the active layer 104 further decreases, and
Since the differential gain of the active layer 104 further decreases due to the influence of heat generation, it becomes difficult for the gain received by the guided light to exceed the loss. As described above, the oscillation threshold current rapidly increases. However, when the injection current value further increases, the gain received by the guided light at a certain injection current value exceeds the loss, and laser oscillation occurs to increase the optical output sharply. At this time, carriers are excited by the oscillating laser light in the light absorption layer 106, and the light absorption effect is rapidly reduced, so that the light absorption loss received by the guided light is rapidly reduced.
As a result, the gain received by the guided light greatly exceeds the loss, and the optical output after laser oscillation sharply increases, causing non-linearity in current-optical output. The above-described non-linearity of current-light output has to be avoided because it causes a serious problem in practical use.

According to the first embodiment, as described above, the light absorption layer 106 for absorbing the oscillating laser light to generate the saturable absorption effect is provided on the second light guide layer 105, and Since the thickness of the absorption layer 106 is set to 5 nm or more and 12 nm or less, self-excited oscillation that generates a multimode spectrum in laser oscillation characteristics can be realized, and low noise characteristics can be obtained and linearity can be obtained. Current-light output characteristics with excellent properties can be obtained. That is, laser oscillation can be generated in an injected carrier density state in which the differential gain of the active layer 104 does not show a saturation tendency.

Since the thickness of the light absorbing layer 106 is set to 12 nm or less while the thickness of the active layer 104 is 60 nm, the volume of the light absorbing layer 106 itself does not increase. The saturation of the light absorption of the light absorption layer 106 with respect to the generated oscillation laser light does not become difficult. For this reason, since it is not necessary to increase the gain of the guided light in the active layer 104, it is not necessary to increase the current injection amount, and it is possible to prevent a large increase in the operating current value, thereby increasing the heat generation amount of the semiconductor laser device. It is possible to prevent a decrease in reliability. Further, since the light absorption layer 106 has a small thickness, no deformation occurs in the vertical light distribution, so that the vertical beam pattern in the far-field image does not have asymmetry. A reduction in the coupling efficiency between the emitted light and the lens can be avoided.

The thickness of the light absorption layer 106 for obtaining current-light output characteristics with excellent linearity varies depending on the thickness of the active layer 104. That is, when the film thickness of the active layer 104 is larger, the operating carrier density decreases, and the semiconductor laser device is operated at an operating point having a higher differential gain, and the light confinement coefficient of the active layer 104 is reduced. Since the ratio increases, the ratio of the increase of the gain of the guided light to the increase of the injection current increases, so that non-linearity hardly occurs in the current-light output characteristics.

FIG. 4 shows the experimental results of the dependence of the oscillation spectrum characteristics on the bandgap wavelength difference Δλ and the thickness of the light absorbing layer 106 when the thickness of the active layer 104 is 80 nm, and the current-light output. The experimental results on the presence or absence of nonlinearity in the characteristics are shown. FIG. 4 shows the characteristics in the case where the film thickness of the second light guide layer 105 is 0.24 μm at which stable fundamental transverse mode oscillation can be performed.

As can be seen from FIG. 4, as the thickness of the active layer 104 increases, the area where self-excited oscillation occurs without causing nonlinearity in the current-light output characteristics increases. this is,
As described above, when the thickness of the active layer 104 is increased, the rate of increase of the gain of the guided light with respect to the increase of the injection current increases, so that the current-light output characteristics are less likely to have nonlinearity. When the thickness of the active layer 104 is 80 nm, the thickness of the light absorption layer 106 is 5 nm or more and 16 n
It can be seen that it is necessary to set it to m or less.

FIG. 5 shows the relationship between the thickness of the active layer 104 and the maximum thickness of the light absorbing layer 106 for preventing non-linearity in current-light output characteristics. When the film thickness of the light absorption layer 106 is set in a region indicated by oblique lines in FIG. 5, self-pulsation can be obtained without causing nonlinearity in current-light output characteristics.

From the above examination, when the thickness of the active layer 104 is 30 nm or more and 80 nm or less, which is usually adopted, the thickness of the light absorption layer 106 is set to 1/5 or less of the thickness of the active layer 104. It can be seen that, when set to, non-linearity does not occur in the current-light output characteristics.

When a plurality of light absorbing layers 106 are provided, if the total thickness of the plurality of light absorbing layers 106 is set to be not more than ５ of the thickness of the active layer 104, In the case where the absorption layer 106 has a quantum well structure, if the total thickness of each well layer is set to be equal to or less than one fifth of the thickness of the active layer 104, no non-linearity occurs in the current-light output characteristics. .

Hereinafter, the lateral light distribution and the astigmatic difference will be discussed.

The light distribution in the lateral direction is determined by the width W of the current channel and the effective refractive index difference Δn between the inside and outside of the current channel.

In the first embodiment, the current channel width W is set to 4 μm in order to reduce the light absorption loss of the guided light in the current blocking layer 108 and obtain the fundamental transverse mode oscillation.

The effective refractive index difference Δ between the inside and outside of the current channel Δ
n is determined by the total film thickness dp of the second light guide layer 105 and the light absorption layer 106. FIG. 6 shows the inner and outer effective refractive index difference Δ
The calculation result about the dependence of n on the total film thickness dp is shown. In this calculation, the thickness of the light absorption layer 106 is 10 nm. As shown in FIG.
It can be seen that as p becomes smaller, the effective refractive index difference Δn between inside and outside becomes larger. Prevents the waveguide mechanism from changing from a refractive index waveguide mechanism to an anti-refractive index waveguide mechanism due to a decrease in the effective refractive index inside the current channel due to the plasma effect due to current injection, and provides stable fundamental transverse mode oscillation. For this purpose, a value of 3 × 10 ⁻³ or more is required as the inner and outer effective refractive index difference Δn. Therefore, the second light guide layer 105 and the light absorbing layer 106
It can be seen that the value of the total film thickness dp must be 0.3 μm or less.

If a semiconductor laser device is manufactured so that the total thickness dp of the second light guide layer 105 and the light absorption layer 106 is 0.3 μm or less, stable fundamental transverse mode oscillation can be obtained. At the same time, the confinement of the light distribution in the lateral direction into the current channel is increased, and the guided light is applied to the current blocking layer 10 in the current blocking layer 108 and the active layer 104.
8, the light absorption loss received in the lower portion can be reduced, so that the oscillation threshold current can be reduced and the curvature of the horizontal equiphase surface of the guided light can be reduced. The curvature of the equal phase plane causes an astigmatic difference, which makes it difficult to converge the emitted light in a spot shape by a lens, thereby causing a practical problem. Therefore, if the semiconductor laser device is manufactured so that the value of the total thickness dp of the second light guide layer 105 and the light absorption layer 106 becomes 0.3 μm or less, the oscillation threshold current can be reduced and the non-wavelength of 5 μm or less can be reduced. Realization of a point difference can be achieved.

In the calculation shown in FIG. 6, the thickness of the light absorbing layer 106 is set to 10 nm.
Is less than 12 nm, the thickness of the light absorption layer 106 is very small, so that the light distribution is hardly affected, and the total thickness dp of the second light guide layer 105 and the light absorption layer 106 is zero. .3 μm or less, the effective refractive index difference Δn between inside and outside is 3 × 1
Needless to say, it becomes 0 ^-3 or more.

Although the calculation shown in FIG. 6 is based on the assumption that the thickness of the active layer 104 is 60 nm, it is assumed that the thickness of the active layer 104 is not less than 30 nm and not more than 80 nm, which is usually adopted. Needless to say, the above description is appropriate.

The active layer 104 and the current blocking layer 10
8 or a plurality of light absorbing layers 106 exist between the active layer 104 and the current blocking layer 108.
It is needless to say that the above-described description is valid even when the semiconductor layer 06 is not provided, as long as the total thickness of the semiconductor layers existing between the active layer 104 and the current blocking layer 108 is 0.3 μm or less.

In the first embodiment, the total thickness of the second light guide layer 105 and the light absorption layer 106 is 0.25 μm.
Since the light distribution below the current blocking layer 107 is pushed to the semiconductor substrate 101 side, the effective refractive index of the light distribution below the current blocking layer 107 decreases. Therefore, the effective refractive index difference Δn inside and outside the current channel can be as large as 8 × 10 ⁻³ , so that the lateral distribution of light can be confined in the current channel. Therefore, seepage of the light distribution to the outside of the current channel is reduced, the light absorption loss of the guided light in the current blocking layer 108 and the lower portion of the stripe region 107 in the active layer 104 is reduced, and the astigmatic difference is reduced. Become.

FIG. 7A shows current-light output characteristics of the semiconductor laser device according to the first embodiment, and FIG. 7B shows a conventional self-pulsation type semiconductor laser device having a light absorption layer. 4 shows current-light output characteristics. The resonator length of each semiconductor laser device used for the measurement was 300 μm, and the end face of the semiconductor laser device was not coated.

It can be seen that, in the conventional semiconductor laser device, after the laser oscillation, the light output sharply increases until the light output reaches about 5 mW. When such characteristics appear, 3 mW required when reading information from the optical disc is required.
AP to keep the light output constant when the light output is about
C-drive became impossible, causing a serious problem in practical use.

However, in the semiconductor laser device according to the first embodiment, the oscillation threshold current is 40 mA, and the maximum light output is 30 mW. In addition, non-linearity that makes APC driving impossible is not observed in the current-light output characteristics, and characteristics excellent in linearity are obtained.
The transverse mode oscillated in a stable basic mode. The spectrum oscillates in a multi-mode that generates self-pulsation in the 780 nm band, and has a RIN value of -130 dB / Hz or less within the range of a return light rate of 0 to 10%, and low noise characteristics can be obtained. Was. Furthermore, the astigmatic difference is 3 μm
Thus, the characteristic of low astigmatic difference was obtained.

Hereinafter, a mixed crystal ratio of each layer constituting the semiconductor laser device according to the first embodiment will be described.

First, the first to third light guide layers 103, 1
AlAs mixed crystal ratios of Al and Al of active layer 104 and AlAs
The relationship with the As mixed crystal ratio will be described.

When using a laser beam having a wavelength in the 780 nm band used for an optical pickup device such as an optical disc,
In order to prevent the injected carriers from overflowing from the active layer 104 and effectively confine the carriers in the active layer 104, in the first embodiment, each of the first to third light guide layers 103, 105, and 109 is used. The AlAs mixed crystal ratio is set to 0.5. However, the AlAs mixed crystal ratio of each of the first to third light guide layers 103, 105, and 109 is different from that of the active layer 1
Needless to say, carriers can be effectively confined in the active layer 104 if the ratio is at least 0.3 or more than the AlAs mixed crystal ratio of 0.15, which is 04.

Hereinafter, the forbidden bandwidth wavelength (the wavelength of light corresponding to the energy of the forbidden bandwidth) of the light absorbing layer 106 will be described.

In order to cause the light absorption layer 106 to absorb laser light and obtain a saturable absorption effect, the band gap wavelength of the light absorption layer 106 needs to be longer than the band gap wavelength of the active layer 104. Bandgap wavelength of light absorbing layer 106 and active layer 10
If the forbidden bandwidth difference Δλ (the forbidden bandwidth of the light absorbing layer 106-the forbidden bandwidth of the active layer 104), which is a difference from the forbidden bandwidth of No. 4, is smaller than 4 nm, the light absorbing layer 106
In this case, carriers are excited by laser light oscillated from the active layer 104, so that the laser light easily becomes transparent to the laser light. Therefore, the saturable absorption effect of the light absorbing layer 106 is weakened at the time of low light output of 1 mW or less, and self-pulsation does not occur at the time of light output of 1 mW or more.

On the other hand, when the forbidden bandwidth wavelength difference Δλ is larger than 10 nm, the light absorption of the light absorbing layer 106 becomes too large, and light absorption saturation hardly occurs. In this case, in order to make the laser oscillate, it is necessary to increase the amount of injection current to compensate for the light absorption loss of the light absorption layer 106 and increase the gain of the guided light in the active layer 104. However, when the amount of injected current is increased, a large increase in oscillation threshold current and a decrease in external differential quantum efficiency are caused.

Accordingly, in order to obtain self-sustained pulsation without causing a large increase in the oscillation threshold current, the band gap wavelength difference Δλ should be set to a value within a range from 4 nm to 10 nm. It is necessary to manufacture a semiconductor laser device. Therefore, in the first embodiment, the forbidden bandwidth wavelength difference Δλ
Is set to 6 nm, the AlAs mixed crystal ratio of the light absorption layer 106 is set to 0.14, which is smaller than the AlAs mixed crystal ratio of the active layer 104 by 0.01.

Hereinafter, a method of manufacturing the semiconductor laser device according to the first embodiment will be described with reference to FIGS.

First, as shown in FIG. 8A, an n-type G
n-type GaAs is formed on a semiconductor substrate 101 made of aAs.
a buffer layer 102 of _0.5 μm in thickness, a first optical guide layer 103 of 2.0 μm in thickness of n-type Ga _0.5 Al _0.5 As, and an active layer of 0.06 μm in thickness of Ga _0.85 Al _0.15 As. Layer 104, p-type Ga _0.5 Al _0.5
0.24 μm thick second light guide layer 10 made of As
5, p-type Ga _0.86 Al _{0. 14} consisting As thickness 0.01
A light absorbing layer 106 having a thickness of μm and a current blocking layer 108 having a thickness of 1.0 μm made of n-type GaAs are sequentially formed.

Next, as shown in FIG. 8B, the current block layer 108 is etched by using the photolithography technique, so that the stripe region 107 is etched.
A regular mesa-shaped concave groove having a width of 4 μm is formed. The shape of the concave groove is preferably a forward mesa shape rather than an inverted mesa shape. The reason is that in the case of the inverted mesa shape, crystal growth in the concave groove becomes more difficult than in the case of the forward mesa shape,
This is because there is a possibility that the yield may be reduced due to the deterioration of the characteristics. Actually, when an inverted mesa-shaped concave groove was formed, GaAlAs was formed on the side of the stripe region 107.
The crystallinity of the semiconductor laser device was impaired, and the threshold current of the obtained semiconductor laser device was increased by about 10 mA as compared with the case of the forward mesa shape.

Next, as shown in FIG. 8C, the MOCV
A p-type Ga _0.5 Al _0.5 As layer is grown on the light absorption layer 106 by the D method or the MBE method.
Stripe region 107 having a width of 4 μm
And a 2.0 μm-thick third light guide layer 109 made of p-type Ga _0.5 Al _0.5 As is formed on the stripe region 107 and the current block layer 108.
After that, a contact layer 110 made of p-type GaAs and having a thickness of 2.0 μm is formed on the third light guide layer 109 by a regrowth method. In this case, the dopant of the p-type Ga _0.5 Al _0.5 As layer forming the third light guide layer 109 is Z
In the case of using n, in order to prevent the characteristics from being affected by the diffusion of Zn into the stripe region 107 during growth,
The carrier concentration should be at least 10 ¹⁸ c at the regrowth interface.
m ^-3 or less. In the first embodiment, the carrier concentration is set to 7 × ¹⁷ cm ⁻³ . Note that a dopant having low diffusivity such as carbon may be used as the dopant. Thereafter, although not shown, electrodes are formed on the lower surface of the semiconductor substrate 101 and the upper surface of the contact layer 110, respectively.

Hereinafter, a semiconductor laser device according to a second embodiment of the present invention will be described with reference to FIG.

FIG. 9 shows a cross-sectional structure of a semiconductor laser device according to the second embodiment. As shown in FIG. 9, an n-type G type semiconductor is formed on a semiconductor substrate 201 made of n-type GaAs.
buffer layer 202 made of aAs, n-type Ga _0.5 Al
_0.5 As first optical guide layer 203, p-type Ga
Light absorbing layer 204 of _0.86 Al _0.14 As and n-type G
a first optical guide layer 205 made of a _0.5 Al _0.5 As;
a _0.85 Al _0.15 As Active layer 206 and p-type G
A second light guide layer 207 made of a _0.5 Al _0.5 As is sequentially formed. A stripe region 208 made of p-type Ga _0.5 Al _0.5 As is formed at a central portion on the second light guide layer 207, and n regions are formed on both sides of the stripe region 208 on the second light guide layer 207. A current blocking layer 209 of GaAs is formed. Stripe region 208 and current block layer 2
A third light guide layer 210 made of p-type Ga _0.5 Al _0.5 As is formed integrally with the stripe region 208 on the substrate 09, and the p-type GaAs is formed on the third light guide layer 210.
A contact layer 211 is formed. In the second embodiment, the thickness of the light absorption layer 204 is set to 5 nm or more and 1/5 or less of the thickness of the active layer 206, and the thickness of the second light guide layer 207 is set to 0.1 mm. It is set to 3 μm or less.

FIG. 10 shows a cross-sectional structure of the semiconductor laser device according to the third embodiment. As shown in FIG.
On a semiconductor substrate 301 made of n-type GaAs, a buffer layer 302 made of n-type GaAs and an n-type Ga _0.5
First light guide layer 303 made of Al _0.5 As, p-type G
a light absorption layer 304 made of a _0.86 Al _0.14 As and a first light guide layer 305 made of n-type Ga _0.5 Al _0.5 As;
Active layer 306 made of Ga _0.85 Al _0.15 As, p-type G
The second optical guide layer 307 made of a _0.5 Al _0.5 As and the third guide layer 30 made of p-type Ga _0.8 Al _0.2 As
8 are sequentially formed. On with stripe region 309 made of p-type Ga _0.5 Al _{0. 5} As the center portion is formed in the third optical guide layer 308 on both sides of the stripe region 309 in the top of the third optical guide layer 308 Has a current block layer 310 made of n-type GaAs. A fourth light guide layer 311 made of p-type Ga _0.5 Al _0.5 As is formed integrally with the stripe region 309 on the stripe region 309 and the current block layer 310, and a p-type light guide layer 311 is formed on the fourth light guide layer 311. Type G
A contact layer 312 made of aAs is formed.
In the third embodiment, the thickness of the light absorption layer 304 is 5
The thickness is set to be not less than nm and not more than one fifth of the thickness of the active layer 306, and the total thickness of the second light guide layer 307 and the third light guide layer 308 is set to be 0.3 μm or less. I have.

FIG. 11 shows a cross-sectional structure of a semiconductor laser device according to the fourth embodiment. As shown in FIG.
On a semiconductor substrate 401 made of n-type GaAs, a buffer layer 402 made of n-type GaAs and an n-type Ga _0.5
A first light guide layer 403 made of Al _0.5 As, Ga _0.85
Active layer 404 made of Al _0.15 As, p-type Ga _0.5 A
a second light guide layer 405 of l _0.5 As, p-type Ga
Light absorbing layer 406 made of _0.86 Al _0.14 As and p-type G
A second light guide layer 407 made of a _0.5 Al _0.5 As is sequentially formed. A stripe region 409 made of p-type Ga _0.5 Al _0.5 As is formed at the center on the second light guide layer 407, and n regions are formed on both sides of the stripe region 409 on the second light guide layer 407. A current blocking layer 410 of GaAs is formed. Stripe region 409 and current block layer 4
A third light guide layer 411 made of p-type Ga _0.5 Al _0.5 As is formed integrally with the stripe region 409 on the upper surface 10, and p-type GaAs is formed on the third light guide layer 411.
A contact layer 412 is formed. In the fourth embodiment, the thickness of the light absorption layer 406 is set to 5 nm or more and 1/5 or less of the thickness of the active layer 404, and the two second light guide layers 405 and 407 are formed. And the total thickness of the light absorbing layer 406 interposed therebetween is 0.3
μm or less.

FIG. 12 shows a sectional structure of a semiconductor laser device according to the fifth embodiment. As shown in FIG.
On a semiconductor substrate 501 made of n-type GaAs, a buffer layer 502 made of n-type GaAs and an n-type Ga _0.5
A first light guide layer 503 made of Al _0.5 As, Ga _0.85
Active layer 504 made of Al _0.15 As, p-type Ga _0.5 A
a second light guide layer 505 of l _0.5 As, p-type Ga
Light absorption layer 506 made of _0.86 Al _0.14 As, p-type Ga
_A second light guide layer 507 of _0.5 Al _0.5 As and p
Guide layer 508 of Ga _0.8 Al _0.2 As type
Are sequentially formed. A stripe region 509 made of p-type Ga _0.5 Al _0.5 As is formed at the center on the third light guide layer 508, and n regions are formed on both sides of the stripe region 509 on the third light guide layer 508. A current blocking layer 510 of GaAs is formed. On the stripe region 509 and the current block layer 510, a fourth light guide layer 511 made of p-type Ga _0.5 Al _0.5 As is formed integrally with the stripe region 509. Type Ga
A contact layer 512 made of As is formed. In the fifth embodiment, the thickness of the light absorbing layer 506 is 5n.
m and not more than 分 の of the thickness of the active layer 504, and two second light guide layers 505 and 50.
7. The total film thickness of the light absorbing layer 506 and the third light guide layer 508 interposed therebetween is set to 0.3 μm or less.

FIG. 13 shows a sectional structure of a semiconductor laser device according to the sixth embodiment. As shown in FIG.
On a semiconductor substrate 601 made of n-type GaAs, a buffer layer 602 made of n-type GaAs and an n-type Ga _0.5
A first light guide layer 603 made of Al _0.5 As, Ga _0.85
Al of the active layer 604 and a p-type consisting of _0.15 As Ga _{0. 5}
A second light guide layer 605 made of Al _0.5 As is sequentially formed. A stripe region 606 made of p-type Ga _0.5 Al _0.5 As is formed at a central portion on the second light guide layer 605, and the second light guide layer 605 is formed.
A current block layer 607 made of n-type GaAs is formed in a region except for a central portion on the substrate. A third light guide layer 608 made of p-type Ga _0.5 Al _0.5 As is formed integrally with the stripe region 606 on the current block layer 607, and a p-type light guide layer 608 is formed on the stripe region 606 and the third light guide layer 608. A light absorbing layer 609 made of Ga _0.86 Al _0.14 As is formed on the light absorbing layer 609.
Light guide layer 61 of Ga _0.5 Al _0.5 As
0 is formed, and p-type G is formed on the third light guide layer 610.
A contact layer 611 made of aAs is formed.
In the sixth embodiment, the thickness of the light absorbing layer 609 is 5
The thickness is set to be not less than nm and not more than one fifth of the thickness of the active layer 604, and the thickness of the second light guide layer 605 is set to be 0.3 μm or less.

FIG. 14 shows a sectional structure of a semiconductor laser device according to the seventh embodiment. As shown in FIG.
On a semiconductor substrate 701 made of n-type GaAs, a buffer layer 702 made of n-type GaAs and an n-type Ga _0.5
A first optical guide layer 703 made of Al _0.5 As, Ga _0.85
Active layer 704 made of Al _0.15 As, p-type Ga _0.5 A
The second light guide layer 705 of l _0.5 As and p-type G
A third guide layer 706 made of a _0.8 Al _0.2 As is sequentially formed. A stripe region 707 made of p-type Ga _0.5 Al _0.5 As is formed at a central portion on the third light guide layer 706 and the third light guide layer 7 is formed.
N-type GaAs is formed in a region excluding the central portion on
A current block layer 708 is formed. On the current block layer 708, p-type Ga _0.5 Al _0.5 As
A fourth light guide layer 709 made of a stripe region 707
A light absorption layer 710 made of p-type Ga _0.86 Al _0.14 As is formed on the stripe region 707 and the fourth light guide layer 709, and a p-type Ga is formed on the light absorption layer 710. _A fourth light guide layer 711 made of _0.5 Al _0.5 As is formed, and a contact layer 712 made of p-type GaAs is formed on the fourth light guide layer 711. In the seventh embodiment, the thickness of the light absorbing layer 710 is set to 5 nm or more and 1/5 or less of the thickness of the active layer 704, and the second light guide layer 705 and the third
The total film thickness with the light guide layer 706 is set to 0.3 μm or less.

In each of the above embodiments, only the case where the n-type semiconductor substrate is used and the n-type current blocking layer is formed is shown. However, the p-type semiconductor substrate is used and the p-type current blocking layer is formed. May be formed.

In each of the above embodiments, only the case where the current blocking layer is located above the active layer, that is, the case where the current blocking layer is located on the side opposite to the semiconductor substrate when viewed from the active layer, has been described. The same effect can be obtained even when the current blocking layer is located on the same side as the semiconductor substrate when viewed from the active layer. In addition, if the current blocking layer has a double confinement structure provided on both the upper and lower sides of the active layer, the leakage current is reduced, so that the operation current can be further reduced.

In each of the above embodiments, when the active layer has a multiple quantum well structure, the oscillation threshold current is reduced and the operating current value is reduced.

FIG. 15 shows that the semiconductor laser device according to the first embodiment performs laser oscillation in the 780 nm band.
5 consisting of Ga _0.95 Al _0.05 As having a thickness of 10 nm
Ga _0.7 Al _0.3 A with 4 nm thickness and well layer
4 shows current-light output characteristics when an active layer having a multiquantum well (MQW) structure including six barrier layers made of s is used. As shown in FIG. 15, when the active layer had an MQW structure, an optical output of 50 mW or more was obtained.

When the active layer has a multiple quantum well structure, the differential gain of the active layer is further increased, so that the region where self-sustained pulsation occurs without causing non-linearity in current-light output characteristics is further widened. In the case where the active layer has a multiple quantum well structure and a plurality of light absorbing layers are provided, the total thickness of the plurality of light absorbing layers is set to を of the total thickness of the well layers of the active layer. When the light absorbing layer has a quantum well structure, the total thickness of the light absorbing layer is set to be 1/5 or less of the total thickness of the active layer. Non-linearity in the current-light output characteristics is more unlikely to occur.

As the active layer, a single quantum well (SQW) structure and a double quantum well (DQ
Other multiple quantum well structures such as a W) structure, a triple quantum well (TQW) structure, a grin (GRIN) structure, or a separate confinement heterostructure (SCH) structure can also be employed.

If the current block layer is formed on a semiconductor layer which facilitates regrowth, that is, a semiconductor layer having a small AlAs mixed crystal ratio, regrowth will be performed on a semiconductor layer having a low AlAs mixed crystal ratio. Therefore, oxidation of the regrowth interface can be prevented, and it goes without saying that the interface resistance is reduced.

Further, in each of the above embodiments, Ga
Although the case where an AlAs-based semiconductor material is used has been shown, other material systems, for example, InP-based, InGaAsP-based, and InG-based
aP, InGaAlP, ZnSe, ZnCdSS
It goes without saying that a compound semiconductor material such as e-based, ZnMgSSe-based, GaN-based, InGaN-based, or AlGaN-based may be used.

Hereinafter, an optical pickup device using the semiconductor laser device according to each of the above embodiments as a light source will be described.

FIG. 16 shows a schematic structure of a first optical pickup device using the semiconductor laser device according to each of the above embodiments as a light source. In the description of the first optical pickup device, the same members as those of the first conventional optical pickup device described with reference to FIG. In FIG.
Reference numeral 30B denotes the semiconductor laser device according to each of the embodiments.

As is clear from the comparison between FIG. 16 and FIG. 19, when the semiconductor laser device 30B according to each of the above embodiments is used as a light source, the oscillation spectrum required in the first conventional optical pickup device is reduced. The high frequency superimposing circuit module 38 for multi-mode operation becomes unnecessary.

The high frequency superimposing circuit module 38 is very large and expensive, which hinders miniaturization of the optical pickup device, reduction in the number of parts, and reduction in cost. According to the first optical pickup device using 30B as a light source,
Since the high-frequency superimposing circuit module 38 is unnecessary, it goes without saying that the size and cost of the optical pickup device can be reduced.

FIG. 17 shows a schematic structure of a second optical pickup device using the semiconductor laser device according to each of the above embodiments as a light source. In the description of the second optical pickup device, the same members as those of the second conventional optical pickup device described with reference to FIG. In FIG.
Reference numeral 40B denotes a laser unit in which the semiconductor laser device, the light receiving element, and the hologram optical element according to the above embodiments are integrated.

As is clear from the comparison between FIG. 17 and FIG. 20, when the laser unit 40B having the semiconductor laser device according to each of the above embodiments is used, the high frequency superposition required in the second conventional optical pickup device is required. The circuit module 44 and the shield member 45 become unnecessary. The laser unit requires a terminal for a light receiving element in addition to a terminal for a semiconductor laser device, and thus has a large number of terminals and a complicated structure. In order to attach the high-frequency superimposed circuit module 44 to such a laser unit, the high-frequency superimposed circuit module 44 itself becomes complicated due to the multi-terminal support, which has been a cause of an increase in size and cost. In addition, the high frequency supplied from the high-frequency superimposing circuit module 44 not only causes a problem as unnecessary radiation but also directly affects an electric circuit such as a light receiving element of the laser unit, thereby deteriorating signal characteristics.

However, in the second optical pickup device, a high-frequency superimposing circuit is not required in the laser unit 40B, so that the problem of unnecessary radiation and the problem of the high frequency affecting an electric circuit such as a light receiving element are eliminated. The optical pickup device has a very simple configuration,
It is easy to reduce the number of parts and reduce costs.

[0133]

According to the present invention, claims 1, 6, 11, 16, 21, and 26 are provided.
Alternatively, in the semiconductor laser device according to the thirty-first aspect, since the thickness of the light absorption layer is 5 nm or more, self-sustained pulsation can be generated. In addition, since the thickness of the light absorbing layer is less than one fifth of the thickness of the active layer, current-light output characteristics excellent in linearity can be realized. It is easy to control the magnitude of the output.

According to the semiconductor laser device of the third , seventh, twelfth, twelfth, twelfth, twelfth, twelfth, twelfth and thirty-second aspects, a stable fundamental transverse mode oscillation can be obtained because a refractive index guiding mechanism can be secured. Reducing the light absorption loss of the guided light in the current blocking layer and the region below the current blocking layer in the active layer, thereby reducing the curvature of the equal phase plane of the guided light, thus reducing the astigmatic difference. Can be.

According to the semiconductor laser device of the fourth , eighth, thirteenth, eighteenth, thirteenth, twenty-third, thirty-eighth or thirty-third inventions, since the light absorption layer has a quantum well structure, the thickness of the light absorption layer is small. Even so, the saturable absorption effect of the light absorbing layer can be increased.

According to the semiconductor laser device of the second , ninth, nineteenth, fourteenth, nineteenth, twenty-four, twenty-ninth, or thirty-fourth aspects, the active layer has a multiple quantum well structure, so that the thickness of the active layer is small. Also, the oscillation threshold current can be reduced.

Claims 5, 10, 15, 20, 25, 30
According to the semiconductor laser device of the present invention, the light absorption layer has a quantum well structure and the active layer has a multiple quantum well structure. Even if it is small, the saturable absorption effect of the light absorbing layer can be increased and the oscillation threshold current can be reduced. In addition, since the light absorption layer becomes transparent to the oscillating laser light quickly, self-sustained pulsation is easily generated, and current-light output characteristics with excellent linearity even at a low oscillation threshold current can be realized. it can.

According to the optical pickup device of the present invention, since the semiconductor laser device generates self-sustained pulsation, a high-frequency superimposing circuit module becomes unnecessary, and
Since the astigmatism is small, the difference between the value of the astigmatism at the time of reading information from an optical disk or the like and the value of the astigmatism at the time of writing information is also small, so that an optical component for correcting the astigmatism becomes unnecessary. Thus, it is possible to reduce the number of parts, reduce the size, and reduce the cost. Further, since the high-frequency superimposed circuit module becomes unnecessary, the problem of unnecessary radiation and adverse effects on other circuits due to the superimposed high frequency can be solved, and the safety and the characteristics can be improved. Furthermore, linearity can be obtained in the current-light output characteristics in a range from an optical output of about 3 mW suitable for reading information on an optical disc to an optical output of about 30 mW suitable for writing information. And stable reading and writing become possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 shows a case where the thickness of an active layer is 60 nm.
FIG. 7 is a diagram showing the dependence of the oscillation spectrum characteristic on the bandgap wavelength difference Δλ and the thickness of the light absorption layer, and the experimental results of the presence / absence of nonlinearity in the current-light output characteristics.

FIG. 3 is a diagram illustrating non-linearity in current-light output characteristics.

FIG. 4 shows a case where the thickness of an active layer is 80 nm.
FIG. 7 is a diagram showing the dependence of the oscillation spectrum characteristic on the bandgap wavelength difference Δλ and the thickness of the light absorption layer, and the experimental results of the presence / absence of nonlinearity in the current-light output characteristics.

FIG. 5 is a diagram showing the relationship between the thickness of an active layer and the maximum thickness of a light absorbing layer for preventing non-linearity in current-light output characteristics.

FIG. 6 is a diagram showing a calculation result of a dependence of an inner and outer effective refractive index difference Δn on a total film thickness dp of a second light guide layer and a light absorbing film.

FIG. 7A shows current-light output characteristics of the semiconductor laser device according to the first embodiment, and FIG. 7B shows current-light output of a conventional self-pulsation type semiconductor laser device having a light absorption layer. FIG. 4 is a diagram illustrating output characteristics.

FIGS. 8A to 8C are cross-sectional views illustrating respective steps of a method for manufacturing the semiconductor laser device according to the first embodiment.

FIG. 9 is a sectional view of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 10 is a sectional view of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 11 is a sectional view of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 12 is a sectional view of a semiconductor laser device according to a fifth embodiment of the present invention.

FIG. 13 is a sectional view of a semiconductor laser device according to a sixth embodiment of the present invention.

FIG. 14 is a sectional view of a semiconductor laser device according to a seventh embodiment of the present invention.

FIG. 15 is a diagram showing current-light output characteristics when an active layer having a multiquantum well structure is used in the semiconductor laser device according to the first embodiment.

FIG. 16 is a schematic configuration diagram of a first optical pickup device using the semiconductor laser device according to each of the embodiments.

FIG. 17 is a schematic configuration diagram of a second optical pickup device using the semiconductor laser device according to each of the embodiments.

FIG. 18 shows a first conventional example using a conventional semiconductor laser device.
FIG. 2 is a schematic configuration diagram of the optical pickup device of FIG.

FIG. 19 shows a second conventional example using a conventional semiconductor laser device.
FIG. 2 is a schematic configuration diagram of the optical pickup device of FIG.

FIG. 20 is a sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

 30B Semiconductor laser 31 Collimating lens 32 Beam splitter 33 Objective lens 34 Optical disk 35 Detection lens 36 Hologram optical element 37 Light receiving element 40B Laser unit 41 Collimating lens 42 Objective lens 43 Optical disk 101 Semiconductor substrate 102 Buffer layer 103 First optical guide layer 104 Active layer Reference Signs List 105 second light guide layer 106 light absorption layer 107 stripe region 108 current blocking layer 109 third light guide layer 110 contact layer 201 semiconductor substrate 202 buffer layer 203 first light guide layer 204 light absorption layer 205 first light guide layer 206 activity Layer 207 Second light guide layer 208 Stripe region 209 Current block layer 210 Third light guide layer 211 Contact layer 301 Semiconductor substrate 302 Buffer layer 303 First light Id layer 304 Light absorption layer 305 First light guide layer 306 Active layer 307 Second light guide layer 308 Third guide layer 309 Stripe region 310 Current blocking layer 311 Fourth light guide layer 401 Semiconductor substrate 402 Buffer layer 403 First light guide Layer 404 Active layer 405 Second light guide layer 406 Light absorption layer 407 Second light guide layer 409 Stripe region 410 Current block layer 411 Third light guide layer 412 Contact layer 501 Semiconductor substrate 502 Buffer layer 503 First light guide layer 504 Activity Layer 505 Second light guide layer 506 Light absorption layer 507 Second light guide layer 508 Third guide layer 509 Stripe region 510 Current block layer 511 Fourth light guide layer 512 Contact layer 601 Semiconductor substrate 602 Buffer layer 603 First light guide layer 604 Active layer 605 Second light guide layer 606 Stripe region 607 Current block layer 608 Third light guide layer 609 Light absorption layer 610 Third light guide layer 611 Contact layer 701 Semiconductor substrate 702 Buffer layer 703 First light guide layer 704 Active layer 705 Second light guide layer 706 Third guide layer 707 Stripe region 708 Current block layer 709 Fourth light guide layer 710 Light absorption layer 711 Fourth light guide layer 712 Contact layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideyuki Nakanishi 1-1, Komachi, Takatsuki-shi, Osaka Inside Matsushita Electronics Corporation (56) References JP-A-8-250805 (JP, A) JP-A Heisei 5-335681 (JP, A) JP-A-7-22695 (JP, A) JP-A-5-291688 (JP, A) JP-A-7-86676 (JP, A) JP-A-63-202083 (JP, A) A) Appl. Phys. Lett. Vol. 65 No. 10 (1994) p. 1211-1212 (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50

Claims (42)

(57) [Claims] A first light guide layer formed of a semiconductor layer of a first conductivity type formed on a semiconductor substrate; an active layer formed of a semiconductor layer formed on the first light guide layer; A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a light beam made of the semiconductor layer of the second conductivity type and absorbing laser light oscillated from the active layer is formed on the second light guide layer. An absorption layer is formed, and a second portion is formed at a central portion on the light absorption layer.
A stripe region made of a conductive semiconductor layer is formed,
A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light absorption layer, and is formed on the stripe region and the current block layer. A third light guide layer of the second conductivity type is formed, and the thickness of the light absorption layer is 5 nm.
It is set to not less than one fifth of the thickness of the active layer.
The band gap between the light absorbing layer and the active layer.
A semiconductor laser device wherein the value of the length difference is 4 nm or more and 10 nm or less . 2. A semiconductor device of a first conductivity type, comprising:
A first light guide layer is formed, and the first light guide layer
An active layer made of a semiconductor layer is formed on the active layer,
Forming a second light guide layer made of a semiconductor layer of the second conductivity type
And a second conductive type semiconductor layer is formed on the second light guide layer.
Light absorption for absorbing laser light oscillating from the active layer
A collecting layer is formed, and a second layer is formed at a central portion on the light absorbing layer.
A stripe region made of a conductive semiconductor layer is formed,
On both sides of the stripe region on the light absorbing layer
Oscillates from the active layer, comprising a semiconductor layer of the first conductivity type
A current blocking layer for absorbing laser light is formed,
A second conductive type first layer is formed on the trip region and the current blocking layer.
Three light guide layers are formed, and the thickness of the light absorption layer is 5 nm.
It is set to not less than one fifth of the thickness of the active layer.
And which, it said active layer is a semiconductor laser device characterized in that it has a multiple quantum well structure. 3. The semiconductor laser device according to claim 1 , wherein a total film thickness of the second light guide layer and the light absorbing layer is set to 0.3 μm or less. 4. The semiconductor laser device according to claim 1, wherein said light absorption layer has a quantum well structure. 5. The semiconductor laser device according to claim 1, wherein the light absorption layer has a quantum well structure, and the active layer has a multiple quantum well structure. 6. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a stripe region made of the semiconductor layer of the second conductivity type is formed at the center on the second light guide layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light guide layer, and a current block layer is formed on the stripe region and the current block layer. A third light guide layer of two conductivity type is formed, and the first light guide layer has at least one light absorption layer that absorbs laser light oscillated from the active layer, and the light absorption layer has a thickness of 5 nm or more and a film of the active layer A semiconductor laser device characterized in that the thickness is set to 1/5 or less. 7. The thickness of the second light guide layer is 0.3 μm.
The semiconductor laser device according to claim 6, wherein: 8. The semiconductor laser device according to claim 6, wherein said light absorption layer has a quantum well structure. 9. The semiconductor laser device according to claim 6, wherein said active layer has a multiple quantum well structure. 10. The semiconductor laser device according to claim 6, wherein said light absorption layer has a quantum well structure, and said active layer has a multiple quantum well structure. 11. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a second conductivity type semiconductor layer is formed thereon, and a second light guide layer made of a second conductivity type semiconductor layer is formed on the second light guide layer with respect to laser light oscillated from the active layer. A transparent third light guide layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed at a central portion on the third light guide layer, and the stripe region is formed on the third light guide layer. A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the semiconductor layer, and a second layer of a semiconductor layer of the second conductivity type is formed on the stripe region and the current block layer. Four light guide layers are formed and The first light guide layer has at least one light absorbing layer that absorbs laser light oscillated from the active layer, and the light absorbing layer has a thickness of 5 nm or more and 5 minutes of the thickness of the active layer. A semiconductor laser device characterized by being set to 1 or less. 12. The semiconductor laser device according to claim 11, wherein a total film thickness of said second light guide layer and said third light guide layer is set to 0.3 μm or less. 13. The semiconductor laser device according to claim 11, wherein said light absorption layer has a quantum well structure. 14. The semiconductor laser device according to claim 11, wherein said active layer has a multiple quantum well structure. 15. The semiconductor laser device according to claim 11, wherein the light absorption layer has a quantum well structure, and the active layer has a multiple quantum well structure. 16. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a stripe region made of the semiconductor layer of the second conductivity type is formed at the center on the second light guide layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light guide layer, and a current block layer is formed on the stripe region and the current block layer. A third light guide layer of a two-conductivity type is formed, and the second light guide layer has at least one which absorbs laser light oscillated from the active layer.
A semiconductor laser device, comprising: a light absorbing layer, wherein the thickness of the light absorbing layer is set to 5 nm or more and 1/5 or less of the film thickness of the active layer. 17. The semiconductor laser device according to claim 16, wherein the thickness of the second light guide layer including the absorption layer is set to 0.3 μm or less. 18. The semiconductor laser device according to claim 16, wherein said light absorption layer has a quantum well structure. 19. The semiconductor laser device according to claim 16, wherein said active layer has a multiple quantum well structure. 20. The semiconductor laser device according to claim 16, wherein said light absorption layer has a quantum well structure, and said active layer has a multiple quantum well structure. 21. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a second conductivity type semiconductor layer is formed thereon, and a second light guide layer made of a second conductivity type semiconductor layer is formed on the second light guide layer with respect to laser light oscillated from the active layer. A transparent third light guide layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed at a central portion on the third light guide layer, and the stripe on the third light guide layer is formed. A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the region, and a third light guide of the second conductivity type is formed on the stripe region and the current block layer. A layer is formed, said second light guide The layer has at least one light-absorbing layer that absorbs laser light oscillated from the active layer, and the light-absorbing layer has a thickness of 5 nm or more and a thickness of 1/5 or less of the active layer. A semiconductor laser device characterized by being performed. 22. The device according to claim 21, wherein a total thickness of the second light guide layer including the light absorption layer and the third light guide layer is set to 0.3 μm or less. Semiconductor laser device. 23. The semiconductor laser device according to claim 21, wherein said light absorption layer has a quantum well structure. 24. The semiconductor laser device according to claim 21, wherein said active layer has a multiple quantum well structure. 25. The semiconductor laser device according to claim 21, wherein the light absorption layer has a quantum well structure, and the active layer has a multiple quantum well structure. 26. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a stripe region made of the semiconductor layer of the second conductivity type is formed at the center on the second light guide layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light guide layer, and a current block layer is formed on the stripe region and the current block layer. A third light guide layer of two conductivity type is formed, and the third light guide layer absorbs at least one laser beam oscillated from the active layer.
A semiconductor laser device, comprising: a light absorbing layer, wherein the thickness of the light absorbing layer is set to 5 nm or more and 1/5 or less of the film thickness of the active layer. 27. The second light guide layer has a thickness of 0.3 μm.
27. The semiconductor laser device according to claim 26, wherein the distance is set to m or less. 28. The semiconductor laser device according to claim 26, wherein the light absorption layer has a quantum well structure. 29. The semiconductor laser device according to claim 26, wherein the active layer has a multiple quantum well structure. 30. The semiconductor laser device according to claim 26, wherein the light absorption layer has a quantum well structure, and the active layer has a multiple quantum well structure. 31. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, an active layer made of a semiconductor layer is formed on the first light guide layer, and A second light guide layer made of a second conductivity type semiconductor layer is formed thereon, and a second light guide layer made of a second conductivity type semiconductor layer is formed on the second light guide layer with respect to laser light oscillated from the active layer. A transparent third light guide layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed at a central portion on the third light guide layer, and the stripe region is formed on the third light guide layer. A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the semiconductor layer, and a second layer of a semiconductor layer of the second conductivity type is formed on the stripe region and the current block layer. Four light guide layers are formed and The fourth light guide layer has at least one light absorbing layer that absorbs laser light oscillated from the active layer, and the light absorbing layer has a thickness of 5 nm or more and 5 minutes of the active layer. A semiconductor laser device characterized by being set to 1 or less. 32. The semiconductor laser device according to claim 31, wherein a total film thickness of said second light guide layer and said third light guide layer is set to 0.3 μm or less. 33. The semiconductor laser device according to claim 31, wherein the light absorption layer has a quantum well structure. 34. The semiconductor laser device according to claim 31, wherein said active layer has a multiple quantum well structure. 35. The semiconductor laser device according to claim 31, wherein the light absorption layer has a quantum well structure, and the active layer has a multiple quantum well structure. 36. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a light beam made of the semiconductor layer of the second conductivity type and absorbing laser light oscillated from the active layer is formed on the second light guide layer. An absorption layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed in the center on the light absorption layer, and a semiconductor of the first conductivity type is formed on both sides of the stripe region on the light absorption layer. A current blocking layer that absorbs laser light oscillated from the active layer; a third light guide layer of a second conductivity type is formed on the stripe region and the current blocking layer; The film thickness is 5
nm or more and less than or equal to 1/5 of the film thickness of the active layer, the total film thickness of the second light guide layer and the light absorbing layer is set to 0.3 μm or less, The activity
The value of the band gap wavelength difference between the
a semiconductor laser device having a diameter of not more than nm, a light collecting unit for collecting a light beam emitted from the semiconductor laser device on an information recording surface, and a light detecting unit for detecting a light beam reflected from the information recording surface. An optical pickup device comprising: 37. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a stripe region made of the semiconductor layer of the second conductivity type is formed at the center on the second light guide layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light guide layer, and a current block layer is formed on the stripe region and the current block layer. A two-conductivity type third light guide layer is formed, and the first light guide layer has at least one layer for absorbing laser light oscillated from the active layer.
A thickness of the light absorbing layer is set to 5 nm or more and 1/5 or less of a thickness of the active layer, and a thickness of the second light guide layer is set to 0.3 μm. A semiconductor laser device set as follows, light collecting means for collecting a light beam emitted from the semiconductor laser device on an information recording surface, and light detection for detecting a light beam reflected from the information recording surface And an optical pickup device. 38. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a second conductivity type semiconductor layer is formed thereon, and a second light guide layer made of a second conductivity type semiconductor layer is formed on the second light guide layer with respect to laser light oscillated from the active layer. A transparent third light guide layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed at a central portion on the third light guide layer, and the stripe region is formed on the third light guide layer. A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the semiconductor layer, and a second layer of a semiconductor layer of the second conductivity type is formed on the stripe region and the current block layer. Four light guide layers are formed and The first light guide layer has at least one light absorbing layer that absorbs laser light oscillated from the active layer, and the light absorbing layer has a thickness of 5 nm or more and 5 minutes of the thickness of the active layer. A semiconductor laser device wherein the total thickness of the second light guide layer and the third light guide layer is set to 0.3 μm or less; and a light beam emitted from the semiconductor laser device An optical pickup device comprising: a light-collecting unit that collects light onto the information recording surface; and a light detecting unit that detects a light beam reflected from the information recording surface. 39. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a stripe region made of the semiconductor layer of the second conductivity type is formed at the center on the second light guide layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light guide layer, and a current block layer is formed on the stripe region and the current block layer. A third light guide layer of a two-conductivity type is formed, and the second light guide layer has at least one which absorbs laser light oscillated from the active layer.
A light-absorbing layer having a thickness of 5 nm or more and 1/5 or less of the film thickness of the active layer. The film thickness is 0.3μ
m, a condensing means for condensing a light beam emitted from the semiconductor laser device on an information recording surface, and a light for detecting a light beam reflected from the information recording surface An optical pickup device comprising: a detection unit. 40. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a second conductivity type semiconductor layer is formed thereon, and a second light guide layer made of a second conductivity type semiconductor layer is formed on the second light guide layer with respect to laser light oscillated from the active layer. A transparent third light guide layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed at a central portion on the third light guide layer, and the stripe on the third light guide layer is formed. A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the region, and a third light guide of the second conductivity type is formed on the stripe region and the current block layer. A layer is formed, said second light guide The layer has at least one light-absorbing layer that absorbs laser light oscillated from the active layer, and the light-absorbing layer has a thickness of 5 nm or more and a thickness of 1/5 or less of the active layer. And a total thickness of the second light guide layer including the light absorption layer and the third light guide layer is set to 0.3 μm or less; and An optical pickup device, comprising: a light-collecting unit that collects an emitted light beam on an information recording surface; and a light detection unit that detects a light beam reflected from the information recording surface. 41. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a semiconductor layer of the second conductivity type is formed thereon, and a stripe region made of the semiconductor layer of the second conductivity type is formed at the center on the second light guide layer; A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the stripe region on the light guide layer, and a current block layer is formed on the stripe region and the current block layer. A third light guide layer of two conductivity type is formed, and the third light guide layer absorbs at least one laser beam oscillated from the active layer.
A thickness of the light absorbing layer is set to 5 nm or more and 1/5 or less of a thickness of the active layer, and a thickness of the second light guide layer is set to 0.3 μm. A semiconductor laser device set as follows, light collecting means for collecting a light beam emitted from the semiconductor laser device on an information recording surface, and light detection for detecting a light beam reflected from the information recording surface And an optical pickup device. 42. A first light guide layer made of a semiconductor layer of a first conductivity type is formed on a semiconductor substrate, and an active layer made of a semiconductor layer is formed on the first light guide layer. A second light guide layer made of a second conductivity type semiconductor layer is formed thereon, and a second light guide layer made of a second conductivity type semiconductor layer is formed on the second light guide layer with respect to laser light oscillated from the active layer. A transparent third light guide layer is formed, a stripe region made of a semiconductor layer of the second conductivity type is formed at a central portion on the third light guide layer, and the stripe region is formed on the third light guide layer. A current block layer made of a semiconductor layer of the first conductivity type and absorbing laser light oscillated from the active layer is formed on both sides of the semiconductor layer, and a second layer of a semiconductor layer of the second conductivity type is formed on the stripe region and the current block layer. Four light guide layers are formed and The fourth light guide layer has at least one light absorbing layer that absorbs laser light oscillated from the active layer, and the light absorbing layer has a thickness of 5 nm or more and 5 minutes of the active layer. A semiconductor laser device in which the total thickness of the second light guide layer and the third light guide layer is set to 0.3 μm or less; An optical pickup device, comprising: a light condensing means for condensing a light beam on an information recording surface; and a light detecting means for detecting a light beam reflected from the information recording surface.