JPH0776810B2 - Light control element - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a light control element for controlling the amount of transmitted light.

[Prior Art] Conventionally, dielectric elements (liquid crystal or PL
There is an optical shutter element that controls the amount of light transmission using the electro-optic effect of ZT).

For example, an optical shutter element using liquid crystal as a dielectric is
A transparent electrode is provided on the facing surface between a pair of glass substrates, the facing electrode surface is oriented, and a liquid crystal is sealed between these glass substrates to form a liquid crystal cell. Polarizing plates whose polarization axes are orthogonal to each other are provided on the upper and lower surfaces, and a driving device applies a predetermined voltage to the upper and lower electrodes to control the amount of light transmission.

Further, the optical shutter element using PLZT as the dielectric is
(Pb _lX La _x ) (Zr _lY Ti _Y ) O ₃ translucent ceramic (hereinafter referred to as PLZT plate) is used, and this PLZT plate is placed between polarizing plates whose polarization axes are orthogonal to each other, and is parallel to this PLZT plate. An electrode is provided on the electrode, and a predetermined voltage is applied to this electrode to control the amount of light transmission.

[Problems of Prior Art] In the former optical shutter element using liquid crystal, it is necessary to dispose two glass substrates having transparent electrodes facing each other with a very small gap, and to enclose the liquid crystal between them. Therefore, the structure of the device is complicated and it is difficult to manufacture a small device. Also, the latter optical shutter element using PLZT is
Since the ZT plate is ceramic, it cannot be made thin or small, and it is still difficult to manufacture a small element.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object thereof is to provide a light control element having a simple structure and capable of easily obtaining an extremely small size. .

In order to achieve the above-mentioned object, the present invention forms a magnetic film on the outer peripheral surface on one end side of an optical fiber that guides light from a light source,
A coil for generating a magnetic field is wound around this magnetic film, and
A magnetic light shutter is provided at one end of the optical fiber, and when the magnetic field generated in the coil acts on the magnetic light shutter via the magnetic film, the magnetic light shutter is opened or closed to control the transmission of light from the light source. It was done like this.

[First Embodiment] An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a principle diagram of a light control element, and reference numeral 1 in the figure is an optical fiber. This optical fiber guides light. A light source 2 for generating a laser beam is arranged on one end side (the left end side in the figure), and a magnetic light shutter 3 is arranged on the other end face (tip).
Further, magnetic films 4 are provided on the outer peripheral surfaces of the other ends, respectively, and a coil 5 is wound around the outer periphery of the magnetic film 4. The coil 5 is connected to a drive circuit 6 and is driven by the drive circuit 6 to generate a magnetic field.

The magnetic film 4 allows the magnetic field generated in the coil 5 to pass through the magnetic optical shutter 3
A ferromagnetic amorphous metal material that has a small coercive force and is easily magnetized in a weak magnetic field, for example,
It is made of an amorphous alloy [(F _e , C _O , N _i ) ₉₀ Z _r10 ] or the like, and is formed by coating from the outer circumference of the optical fiber 1 to the outer circumference of the magnetic optical shutter 3.

The magnetic light shutter 3 controls the amount of light transmission depending on the magnitude of the magnetic field of the magnetic film 4, and includes a thin film 7 made of a transparent magnetic oxide crystal material that allows light to pass through well, and its polarization axes orthogonal to the front and rear surfaces thereof. It is composed of a pair of polarizing films 8 and 8'which are integrally formed. In this case, the transparent magnetic oxide crystal material film 7 may be, for example, cadmium iron garnet (Gd ₃ Fe ₅ O ₁₂ ) having a large Farade rotation angle, or bismuth (Bi) -substituted gadolinium (Gd) (Gd ₂ A crystal film such as BiFe ₅ O ₁₂ ) is used.

In order to manufacture this light control element, first, the polarizing film 8 is formed on the end face of the optically polished fiber by masking the outer peripheral surface of the optical fiber by using a film forming technique such as a sputtering method.
The transparent magnetic oxide crystal material film 7 and the polarizing film 8'may be sequentially formed, and then the surface of the polarizing film 8'may be masked to form an amorphous alloy film on the outer peripheral surface of the fiber on the tip side.

Next, the operation of the light control element configured as described above will be described.

First, a laser beam is generated by the light source 2, and this laser beam is applied to one end (left end in the figure) side of the optical fiber 1. Then, this laser light enters from one end side of the optical fiber 1 and is guided to the front end side (the magnetic light shutter 3 side), but is blocked by the magnetic light shutter 3 and does not leak to the outside. That is, in the transparent magnetic film shutter 3, the polarization axes of the polarizing films 8 and 8 ′ provided before and after the transparent magnetic oxide crystal material film 7 are orthogonal to each other and the magnetic field is zero (a magnetic field is generated). In the unopened state), the polarization plane of the light passing through the transparent magnetic oxide crystal material film 7 does not rotate, so the magnetic light shutter 3 is in the closed state (off state), and the light is not emitted to the outside.

When the drive circuit 6 gives a drive pulse to the coil 5 in this state, the coil 5 generates a magnetic field in the axial direction of the optical fiber in response to the drive pulse, and this magnetic field causes the magnetic optical shutter 3 to pass through the magnetic film 4. To drive. That is, the magnetic film 4 provided on the outer peripheral surfaces of the optical fiber 1 and the magnetic optical shutter 3 is magnetized by a weak magnetic field and has a large magnetic field particularly near the tip of the optical fiber 1 (the magnetic optical shutter 3). for that reason,
The magnetic light shutter 3 rotates the polarization plane of the transmitted light by a large magnetic field and is brought into an open state (on state). The laser light guided by the optical fiber 1 is transmitted and sent out without being blocked. When the drive pulse applied from the drive circuit 6 to the coil 5 is cut off, the magnetic field is in a state of zero (state in which no magnetic field is generated), and the closed state as described above results in the polarization plane of the magnetic optical shutter 3. It returns to the initial state where it does not rotate.

According to the above light control element, the magnetic optical shutter 3 made of a magnetic oxide crystal is provided at the tip of the optical fiber 1, and the ferromagnetic amorphous metal is spread over the outer peripheral surfaces of the magnetic optical shutter 3 and the optical fiber 1. Since the magnetic film 4 such as the above is provided and the coil 5 is wound around the outer periphery of the magnetic film 4, the structure is simple and can be made extremely small. Moreover, even if a slight magnetic field is generated in the coil 5,
A large magnetic field can be applied to the magnetic optical shutter 3 by the magnetic film 4 made of a ferromagnetic amorphous metal or the like. Therefore, the magnetic optical shutter 3 can be opened / closed satisfactorily and the amount of transmitted light can be accurately controlled.

Second Embodiment Next, with reference to FIG. 2, a case where the above-mentioned light control element is applied to optical communication will be described.

In FIG. 2, 10 is a transmitter and 11 is a relay. The transmitter 10 and the relay 11 are connected by an optical fiber 12.
That is, the transmitter 10 sends out an optical signal, and like the above-mentioned light control element, the magnetic optical shutter 3a made of a magnetic oxide crystal is provided at the tip of the optical fiber 12, and
A magnetic film 4a of ferromagnetic amorphous metal or the like is provided over the outer peripheral surfaces of the magnetic optical shutter 3a and the optical fiber 12,
A coil 5a is wound around the outer peripheral surface of the magnetic film 4a. When the coil 5a is driven by the drive circuit 6a, the magnetic light shutter 3a opens and closes, and the laser light from the light source 2a arranged on the side of the magnetic light shutter 3a is given to the optical fiber 12 as an optical signal.

On the other hand, the relay unit 11 receives the optical signal from the transmission unit 10 and transmits it to another device through another optical fiber 13, and the optical signal transmitted through the optical fiber 12 is received by the light receiving element 14. Converted to an electric signal, amplified by the amplifier circuit 15 and then driven by the drive circuit 6b.
Given to. On the other hand, a magnetic optical shutter 3b made of a magnetic oxide crystal is provided at the tip of the other optical fiber 13, and a magnetic film 4b such as a ferromagnetic amorphous metal is provided on each outer peripheral surface of the magnetic optical shutter 3b and the optical fiber 13. In addition, the coil 5b is wound around the outer circumference of the magnetic film 4b. A light source 2b for giving a laser beam to another optical fiber 13 is arranged beside the magnetic light shutter 3b.

When optical communication is performed by such a transmission unit 10 and the relay unit 11, laser light is generated in advance by the light sources 2a and 2b of the transmission unit 10 and the relay unit 11, and the laser light is generated by the optical fibers 12, The magnetic optical shutters 3a and 3b provided at the tip of 13 are irradiated. In this state, first, the drive circuit 6a of the transmitter 10 gives a drive pulse to the coil 5a. Then, a magnetic field is generated in the coil 5a in response to this drive pulse, and this magnetic field acts on the magnetic light shutter 3a, so that the magnetic light shutter 3a opens as described above, and the laser light from the light source 2a is directed to the optical fiber 12. give. The optical fiber 12 transmits the laser light as an optical signal to the relay section 11.

In this way, the optical signal transmitted to the relay section 11 is transmitted to the relay section.
The light receiving element 14 in 11 receives as an electric signal and the amplification circuit
It is amplified by 15 and given to the drive circuit 6b. Then, the drive circuit 6b gives a drive pulse to the coil 5b, and opens the magnetic optical shutter 3b in response to the drive pulse as described above. When the magnetic light shutter 3b is opened and closed in this way, the laser light from the light source 2b is given to another optical fiber 13 and transmitted to another device as an optical signal.

Since the above-mentioned optical communication uses the above-mentioned optical control element in the transmission unit 10 and the relay unit 11, it can be configured extremely compactly, and it can accurately transmit and relay an optical signal, and can perform excellent transmission. it can.

Third Embodiment Next, with reference to FIG. 3, a case where the above-mentioned light control element is applied to a magneto-optical recording device will be described.

FIG. 3 is a principle diagram of the magneto-optical recording apparatus. In the figure, 20 is an optical control element, 21 is a recording medium, and 22 is a magnetic field generator. The light control element 20 has exactly the same configuration as that of the first embodiment described above, and comprises an optical fiber 1, a light source 2, a magnetic light shutter 3, a magnetic film 4, a coil 5, a drive circuit 6 and the like, and the drive circuit 6 records. A drive pulse is applied to the coil 5 according to the information to generate a magnetic field, and the magnetic light shutter 3 is opened by the magnetic field, and the laser light from the light source 2 is applied to the recording medium 21 according to the recorded information. . The recording medium 21 is provided with a recording layer 21a on its surface and records information in response to the irradiation of laser light. The recording medium 21 is composed of a magneto-optical tape or the like and is arranged below the magnetic optical shutter 3. In this case, the recording layer 21 on the surface
a has a weak coercive force when exposed to light.
Perpendicular magnetic recording material (material whose magnetization direction is perpendicular) is used. The magnetization direction of the part where no information is recorded faces downward, and the magnetization direction of the part where information is recorded is reversed and faces upward. Has become. Further, the magnetic field generator 22 applies a magnetic field to the recording medium 21, and includes a core 22a, an auxiliary coil 22b wound around the core 22a, and a drive unit 22c for driving the auxiliary coil 22b. Core 22a
Is a magnetic field generated by the auxiliary coil 22b by the drive unit 22c to make it act on the recording medium 21, and is made of a magnetic material, and corresponds to the magnetic optical shutter 3 of the light control element 20 below the recording medium 21. The recording medium 21 is irradiated with the laser light from the light source 2 through the magnetic light shutter 3, and the recording layer 21a
The coercive force of is reversed in the direction of magnetization.

Next, a case where information is recorded by the magneto-optical recording device configured as described above will be described.

First, a drive signal is applied to the auxiliary coil 22b by the drive unit 22c of the magnetic field generator 22, and a weak magnetic field is always applied to the recording medium 21 by the core 22a. In this state, the recording medium 21 is moved at a constant speed, and laser light is applied from the light source 2 of the light control element 20 to the optical fiber 1. Then, when the recording information is given to the drive circuit 6 of the light control element 20, a magnetic field is generated in the coil 5 according to the information recorded by the drive circuit 6, and the magnetic light at the tip of the optical fiber 1 is generated by the action of this magnetic field. The shutter 3 is opened, and the laser light from the light source 2 is applied to the lower recording medium 21. When the recording layer 21a on the surface of the recording medium 21 is irradiated with the laser light as described above, the coercive force of the irradiated portion is weakened, so that the magnetization direction of the recording layer 21a is the core 22a on the lower side.
The direction is turned upside down under the influence of the magnetic field from. As a result, the information is recorded on the recording medium 21.

Fourth Embodiment Next, with reference to FIG. 4, a case where the above-mentioned light control element is applied to a magneto-optical recording / reproducing apparatus will be described.

FIG. 4 is a principle diagram applied to a magneto-optical recording / reproducing apparatus.
This magneto-optical recording / reproducing apparatus includes an optical control device 30, a recording medium 31,
It is composed of a magnetic field generator 32, a photosensor array 33, etc., and is adapted to record and reproduce information. The light control device 30 is an array of a plurality of the light control elements described above, and includes an optical fiber group 30a, a light source 30b, a drive circuit 30c, and the like. The optical fiber group 30a guides laser light from a light source, and includes a plurality of optical fibers 1 ...
Are arranged in a line shape in the width direction of each of the optical fibers 1 and the magnetic optical shutters 3 are provided at the ends (ends approaching the recording medium 31) of the optical fibers 1 ... The magnetic film 4 is provided and each magnetic film 4
The coil 5 ... Is wound around the outer circumference of.
Each of the coils 5 ... Is connected to a drive circuit 30c and generates a magnetic field in response to a drive pulse from the drive circuit 30c.
・ It is designed to open and close. In this case, in particular, each magnetic optical shutter 3 ...
In addition to being opened and closed by the magnetic field generated in ..., It is also opened and closed by magnetic information recorded on the recording medium 31 described later. The drive circuit 30c is provided with recording information and a read / write signal R / W, and based on these information and signals, the coil 5
.. is provided with a drive pulse, and when the recording information is given in the state where the write signal W is given, the driving pulse is given to each coil 5 ... In accordance with the recording information, and the read signal R is given. When given, the coils 5 ... Are not driven. Each of the optical fibers 1 ... Of the optical fiber group 30a is arranged in a line at the tip end side, but the other end side is guided to one light source 30b so that laser light is given from this light source 30b. Has become.

The recording medium 31 is a transparent tape which is exactly the same as that of the third embodiment described above, has a recording layer on the surface thereof, and the coercive force of the portion irradiated with laser light on this recording layer is weakened. When a magnetic field is applied by a magnetic field generator 32 described later, the magnetization direction of the recording layer is inverted upside down. The recording medium 31 is arranged under the light control device 30 and moves in the front and back direction of the paper surface during recording and reproduction.

The magnetic field generator 32 applies a magnetic field to the recording medium 31 and reverses the magnetization direction of the portion where the coercive force is weakened by the irradiation of the laser beam, and is similar to the third embodiment described above.
Core 32a, plural optical fibers 32b ..., Auxiliary coil 32
c, a driving unit 32d, etc., and a plurality of optical fibers 32b ... Are provided in the core 32a in association with each optical fiber 1 of the light control device 30, and are provided on the outer periphery of the core 32a. A coil 32c is wound around this auxiliary coil 32c.
Generates a magnetic field when driven by the drive unit 32d. In this case, the read / write signal R / W is given to the drive unit 32d, and when the write signal W is given, the auxiliary coil 32c is driven to generate a magnetic field, and when the read signal R is given. The auxiliary coil 32c is not driven and a magnetic field is not generated. The optical fibers 32b ... Are used as the recording medium 3 when reproducing the recorded information.
The laser light is guided from the 1 side to the photo sensor array 33 side.

When the laser light from the light source 30b passes through the optical fiber group 30a and the recording medium 31 and is given through the respective optical fibers 32b ...
The laser light is detected, and a light receiving element (not shown) is arranged at a position corresponding to each optical fiber 32b ... Of the magnetic field generation device 32, and the signal detected by each light receiving element is After being given to the amplifier circuit 34 and amplified, it is given to the signal processing circuit 35 and reproduced as information recorded in the recording medium 31.

Next, the operation of the magneto-optical recording / reproducing apparatus configured as described above will be described.

First, when recording information, a write signal W is applied to the drive circuit 30c of the light control device 30 to set the coils 5 wound around the optical fibers 1 ... At the same time, laser light is applied from the light source 30b to the respective optical fibers 1 ... Of the optical fiber group 30a. In this state,
Since no recording information is given, the drive circuit 30c does not drive the coils 5 ..., The magnetic optical shutters 3 ... At the same time, the write signal W is also given to the drive unit 32d of the magnetic field generator 32, and the core 3
The auxiliary coil 32b wound around 2a is driven to apply a weak magnetic field to the recording medium 31. In this state, the light control device
When the recording information is given to the drive circuit 30c of 30 and the recording medium 31 is moved in the front-back direction of the paper surface, the drive circuit 30c in turn drives each coil 5 ... In response to the record information to generate a magnetic field. The magnetic optical shutters 3 ... Are opened and closed according to the recorded information. Then, the laser light is applied to the lower recording medium 31 according to the opening / closing of each magnetic light shutter 3. As a result, the coercive force of the recording layer of the recording medium 31 is weakened, and the weakened portion has a lower magnetization direction in the magnetic field generator.
Reversed by a magnetic field of 32. As a result, magnetic information is recorded on the recording medium 31.

When reproducing (reading) the information recorded on the recording medium 31, the laser light from the light source 30b is made weaker than that at the time of recording, and each optical fiber 1 ...
・ In this state, the optical control device 30 and the magnetic field generation device 32 are applied.
Read signal R to the drive circuit 30c and the drive unit 32d of
To stop the drive circuit 30c and the drive unit 32d. Then, since the coils 5 ... Of the optical fiber group 30a do not generate a magnetic field, the magnetic light shutters 3 ... Are closed, and the laser light from the light source 30b is blocked. The lower magnetic field generator 32 also does not generate a magnetic field and does not give a magnetic field to the recording medium 31. When the recording medium 31 is moved in the front-back direction of the paper surface in such a state, the weak magnetic field generated from the recording layer of the recording medium 31 magnetizes the magnetic films 4 ... 4 ... Amplifies the magnetic field, and the magnetic field shutter 3 ...
Is driven. However, in this case, since the weak magnetic field generated from the recording layer has different directions in the information recording portion and the non-recording portion, the Farade rotation of the transparent magnetic oxide crystal material film 7 constituting the magnetic optical shutter 3 is performed. The size of the corner is different,
The amount of laser light passing through the magnetic light shutters 3 differs between the information recording part and the non-recording part. The passed laser light is given to the recording medium 31, but since the laser light is weaker than during recording, the coercive force of the recording medium 31 is not weakened and the recorded magnetic information is not destroyed. The laser light thus radiated to the recording medium 31 is given to each optical fiber 32b of the magnetic field generating device 32 through the recording medium 31, and further, the lower photosensor array is passed through this optical fiber 32b. Given to 33, this photo sensor array 33
The information recorded on the recording medium 31 is detected by each light receiving element (not shown) as the amount of light. The information thus detected is amplified as an electric signal by the amplifier circuit 34 and reproduced by the signal processing circuit 35.

Further, when erasing the information recorded on the recording medium 31, a drive pulse is applied to all the coils 5 of the light control device 30 to open the magnetic light shutters 3 ... While irradiating the recording medium 31, by supplying a drive signal in the opposite direction to that at the time of recording to the auxiliary coil 32c of the magnetic field generator 32, a reverse magnetic field is applied to the recording medium 31, and in this state, the recording medium 31 is moved. If moved, the recorded magnetic information can be erased.

It should be noted that in the above-described embodiment, when the recording is reproduced (when reading)
Although the case of the transmissive type for detecting the laser beam transmitted through the recording medium 31 has been described above, the present invention is not limited to this, and the fifth embodiment
A reflective type as shown in the figure may be provided separately. That is, in the structure shown in FIG. 5, the magnetic optical shutter 3 is provided at the tip (lower end) of the optical fiber 1, and the magnetic film 4 is formed on the outer peripheral surface thereof. And the light source 2 is arranged at the other end (upper end) of the optical fiber 1. Then, according to the magnetic information recorded on the recording medium 31, when the magnetic light shutter 3 at the tip is opened, the laser light given from the upper light source 2 to the optical fiber 1 passes through the magnetic light shutter 3 and the recording medium 31. By irradiating the recording layer of, the reflected light is received by the light receiving element 37 through the optical fiber 36 for receiving,
The recorded information is detected and reproduced. Similar to the transmissive type described above, such a reflective type can also reproduce information well.

[Effects of the Invention] As described in detail above, according to the light control element of the present invention, a magnetic film is formed on the outer peripheral surface on one end side of an optical fiber that guides light from a light source, and a magnetic field is generated in this magnetic film. The magnetic light shutter is provided at one end of the optical fiber, and when the magnetic field generated in the coil acts on the magnetic light shutter through the magnetic film, the magnetic light shutter opens or closes, Since the transmission of light is controlled, the amount of transmission of light can be accurately and satisfactorily controlled depending on the magnitude of the magnetic field, and at the same time, an extremely small structure can be easily obtained.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a first embodiment of the present invention, FIG. 2 is a configuration diagram when it is applied to optical communication, FIG. 3 is a principle diagram when it is applied to a magneto-optical recording device, and FIG. FIG. 5 is a principle diagram when applied to a magneto-optical recording / reproducing apparatus, and FIG. 5 is a diagram showing a modified example at the time of reproducing. 1, 12, 13 ... Optical fiber, 2, 2a, 2b, 30b ... Light source, 3, 3a, 3b ... Magnetic optical shutter, 4, 4a, 4b ... Magnetic film, 5, 5a, 5b ... Coil , 20 …… Light control element.

Claims (3)

[Claims] 1. An optical fiber for guiding light from a light source, a magnetic film formed on an outer peripheral surface of one end of the optical fiber, a coil wound around the magnetic film to generate a magnetic field, and connected to the coil. And a magnetic optical shutter provided at one end of the optical fiber and transmitting or blocking light when the magnetic field generated in the coil driven by the drive circuit acts through the magnetic film. Light control element made by. 2. The magnetic optical shutter comprises a thin film made of a transparent magnetic oxide crystal material having a large Farade rotation angle, and a pair of polarizing films integrally provided in front of and behind the thin film. The light control element according to the first section. 3. The light control element according to claim 1, wherein the magnetic film is a ferromagnetic amorphous metal material that is easily magnetized by a minute magnetic field.