JP3121125B2 - Light switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting an optical signal to an arbitrary optical path,
Also, the present invention relates to an optical switch having a function of variably connecting to a light receiving element, and to an optical switch used for optical signal exchange in optical communication, optical interconnection of an optical parallel operation element, and the like.

[0002]

2. Description of the Related Art Optical switches of various structures have been proposed for use in optical signal exchange in optical communication and optical interconnection in optical parallel operation. As one of them, an optical switch shown in FIG. 5 is known. This optical switch includes a matrix drive type liquid crystal panel 210 used for a liquid crystal display or the like. On this liquid crystal panel 210, patterns in which light and dark or refractive index differences are spatially distributed, so-called holograms 211 to 214, are written by electric signals. The input port surface 2 is placed on the portion of the liquid crystal panel 210 on which the holograms 211 to 214 are written.
20 emits optical signals 251 to 254. The optical signals 251 to 254 are transmitted through the liquid crystal panel 210, but are diffracted, that is, deflected at the time of the transmission, and are emitted to target optical paths 261 to 264 reaching the output port surface 230.
Optical signal 25 emitted from the holograms 211 to 214
The degree of deflection of 1 to 254 depends on the pattern recorded as the holograms 211 to 214, and the driving signal input to the liquid crystal panel 210 is changed to change the hologram 211.
To 214, the optical signal 2
The exit points 51-254 are connected to the existing connection optical paths 261-2.
It is configured so that it can be changed from 64 to another.
That is, the holograms 211 to 214 are formed on the matrix-driven liquid crystal panel 210, and the optical paths are switched using a space without using a physical medium such as an optical fiber or an optical waveguide.

[0003]

In the above-described optical switch, since the light is deflected by diffraction of light on the hologram surface, its deflection angle (diffraction angle) is determined.
Depends on the spatial frequency of the hologram surface. For example, assuming that the pattern on the hologram surface is a simple diffraction grating,
Light deflection angle (diffraction angle) θ by the hologram surface
Is represented by the following equation.

Θ = sin ⁻¹ (λ · f) (1) where λ: wavelength of light f: spatial frequency of diffraction grating In a matrix-driven liquid crystal panel used as a hologram recording medium, The size of the smallest pixel that forms the density of the hologram and the distribution of the refractive index depends not on the characteristics of the liquid crystal itself but on the size of the matrix electrode that drives the liquid crystal panel. In this case, the size of one pixel is at least about 0.33 mm. The maximum spatial frequency of the diffraction grating obtained using this pixel size is 1.5 lines / m.
m, and the deflection angle θ of the light obtained by the diffraction grating with respect to the light having the wavelength λ = 1.3 μm is as extremely small as about 0.1 degree according to the above equation (1).

Therefore, in the optical switch having the structure shown in FIG. 5, in order to spatially separate the light output on the output port surface 230, the liquid crystal panel 210 on which a hologram is formed and the output port surface 230 are connected. It is necessary to increase the distance or to provide a lens optical system in the space between them. For example, when the diffraction angle θ is 0.1 degree and the output port surface 230 is 2 mm without using a lens or the like.
In order to perform the separation, the distance between the liquid crystal panel 210 and the output port surface 230 needs to be about 1150 mm. In addition, since the diffraction grating pattern of the liquid crystal panel 210 on which the hologram is formed is written in a matrix by an electric signal, an electric circuit for generating the diffraction grating pattern according to a signal for controlling the connection of the optical path is required. Due to the above, miniaturization and simplification of the optical switch and further high integration have been hindered.

[0006] Further, when the pixel of the liquid crystal panel is made fine in order to increase the diffraction angle on the hologram surface, the manufacturing cost is increased due to the miniaturization of the driving matrix wiring and the high density of the matrix wiring is required. The ratio of opaque parts such as matrix electrodes to the entire liquid crystal panel increases with the development of the liquid crystal panel, that is, the aperture ratio decreases,
There is a problem that the transmittance of the light applied to the liquid crystal panel to the liquid crystal layer, that is, the light use efficiency is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an optical switch capable of achieving miniaturization, simplification, high integration, and improving light use efficiency. The purpose is to provide.

[0008]

An optical switch according to the present invention comprises:
A reflection type spatial light modulator is a hologram pattern which is determined by the intensity of the irradiated light and the voltage applied is recorded, provided on one side sandwiching the spatial light modulation element, the plurality having interfering with one another for forming a hologram light is irradiated to the spatial light modulator, a light generation means for recording a hologram in the spatial light modulator to which a voltage is applied, it is provided on the other side sandwiching the spatial light modulator, to the spatial light modulator towards the recorded hologram is incident optical signal, and an optical output means for receiving the light signal reflected from the hologram, before
The light recording means includes a single light source and a plurality of variable light transmittance types.
And a liquid crystal shutter panel composed of
And generating light for forming each of the holograms from the light source.
To form each liquid crystal cell of the liquid crystal shutter panel.
And irradiates the spatial light modulator through the liquid crystal cell.
By changing the power ratio,
The non-uniformity of light intensity is corrected, thereby achieving the above object.

In the present invention, a plurality of the spatial light modulating elements are provided, and the light generating means irradiates each spatial light modulating element with light for forming a hologram in a time-division manner to separate individual holograms. and to record, for each said hologram recorded the respective spatial light modulator, and simultaneously irradiated a plurality of signal light from the light output means, at the same time the number of optical signals corresponding to the spatial light modulator Processing may be performed in parallel.

[0010]

[0011]

Further, the light generating means emits light from the light source.
The generated light is branched to form the light for forming each hologram.
Pinhole array with multiple pinholes
Mask with the pinhole array mask.
The intensity of the hologram-forming light thus formed is determined by the liquid crystal system.
It may be changed by each liquid crystal cell of the shutter panel .

[0013]

According to the present invention, when a plurality of light beams for forming a hologram are incident on a reflection type spatial light modulation element to which a voltage is applied while interfering with each other, the light reflectance, Alternatively, spatial distribution information of a difference in transmittance or refractive index, that is, a so-called hologram is recorded. When an optical signal is input from the optical input / output unit to the spatial light modulation element on which the hologram is recorded, the optical signal is deflected and reflected according to the hologram, and is captured by the optical input / output unit. At this time,
The hologram is rewritten when the voltage applied to the reflective spatial light modulator and the irradiation position of the light for forming a plurality of holograms are changed. When the hologram is rewritten in this manner, the position where the optical signal is captured by the optical input / output means can be changed to another position. That is, the connection of the optical signal can be switched. In addition, variable transmittance liquid crystal chassis
Hologram emitted from the pinhole using the
By changing the intensity of the light for forming the
Contrast and diffraction of hologram recorded on modulation element
Efficiency can be changed and captured by optical input / output
It is possible to control the intensity of the optical signal.

In addition, a plurality of spatial light modulators are provided, and the light generating means irradiates each spatial light modulator with light for hologram formation in a time-division manner to record individual holograms independently. In the case where a plurality of light signals are simultaneously irradiated from the light input / output means for each spatial light modulation element on which a hologram is recorded, a number of light signals corresponding to the spatial light modulation elements are simultaneously and in parallel. It can be processed.

[0015]

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an optical switch according to this embodiment. This optical switch has a side length of 5 mm
A square-shaped SL in which four reflective spatial light modulators having a square shape, for example, liquid crystal panels 1a to 1d, are arranged on the front and back surfaces, and are arranged two by two vertically and horizontally.
A structure comprising an M array plate 1 and an optical input / output optical system 2 and an address optical system 3 provided at a distance of 42 mm from both sides of the SLM array plate 1 and in parallel with the SLM array plate 1. It has become.

An address optical system 3 is provided on the optical address side 1D of the SLM array plate 1. The address optical system 3 includes a pinhole array mask 31, a liquid crystal shutter panel 32,
A hologram-forming light source including a semiconductor laser element 33 having an emission wavelength of 1.3 μm and a photodiode 34 for monitoring the light output from the semiconductor laser element 33 is provided. The semiconductor laser element 33 includes a semiconductor laser DC drive circuit with an automatic light output control (APC) function (not shown), and generates a laser beam with a constant output based on the optical output monitored by the photodiode 34.

The pinhole array mask 31 is formed, for example, as a pinhole 3 having a round hole shape with a diameter of 0.5 mm.
It has a matte black plate-like shape provided with eight portions 1a to 31h, and is installed in parallel with the SLM array plate 1. FIG. 2 is a plan view of the pinhole array mask 31 as viewed from the SLM array plate 1, and shows the arrangement of the pinholes 31a to 31h in this example. On the back surface of the pinhole array mask 31 opposite to the SLM array plate 1, as shown by dotted lines in FIG.
h, variable light transmittance type liquid crystal cells 32a to 32h having a square shape of, for example, 1 mm × 1 mm.
The liquid crystal shutter panel 32 provided with eight is closely attached. Numerals in parentheses in FIG. 2 indicate points on the xy coordinates of the center of the pinhole in mm.

The liquid crystal shutter panel 32 functions as a shutter for controlling the amount of light from the semiconductor laser element 33. Each of the liquid crystal cells 32a to 32h is provided with electric wiring in a matrix. The light transmittance is controlled by an external electric signal input.

On the other hand, on the liquid crystal layer side 1C of the SLM array plate 1, an optical input / output optical system 2 is provided. The optical input / output optical system 2 includes a pinhole array mask 3 of the address optical system 3.
An optical input / output terminal plate 21 having eight optical fiber connection terminals 2a to 2h is provided at a position symmetrical with the pinholes 31a to 31h provided in the optical fiber connection terminal 1. The optical fiber connection terminals 2a to 2d are for input, and the optical fiber connection terminals 2e to 2h
Is for output.

The liquid crystal panels 1a to 1d constituting the SLM array plate 1 have the same structure as shown in FIG. The specific configuration of each of the liquid crystal panels 1a to 1d is such that a photoconductive layer 12 made of α-SiC, a transparent electrode 14a, and a glass plate 17 are provided on a light shielding plate 16 side of a light shielding plate 16 on which a dielectric reflection film 15 is applied. Are formed. The transparent electrode 14a is formed on a glass plate 17. On the dielectric reflection film 15 side, a ferroelectric liquid crystal layer 13, a transparent electrode 14b, and a polarizing glass plate 18 are formed. The transparent electrode 14b is formed on the polarizing glass plate 18.

Each of the liquid crystal panels 1a to 1d having this configuration is used as an individual cell, and is arranged in a 2 × 2 array to form an SLM.
An array plate 1 is manufactured, and each of the liquid crystal panels 1a to 1d of the SLM array plate 1 has a power supply 19 provided separately.
And an electric wiring to which a predetermined voltage can be applied. Further, the liquid crystal panels 1a to 1d of the present embodiment
It has a resolution of about 250 lines / mm, and when a hologram (diffraction grating) is formed, a maximum of 19 deg. A degree of diffraction angle is obtained.

The above-mentioned SLM array plate 1, addressing optical system 3, and light input / output terminal plate 2 are fixed at predetermined places in a matte black case (not shown).
The address space 4, the optical signal connection space 5, and the address optical system 3 are shielded from light by the above-mentioned case, and have a structure in which external light does not enter. In addition, the structure is such that light that hits the inner surface of the case inside the optical switch is reflected on the inner surface and is prevented from becoming stray light.

The operation of the optical switch configured as described above will be described below. Here, an example in which an optical signal input to the optical fiber connection terminal 2a is connected to the optical fiber connection terminal 2g will be described with reference to FIGS.

A semiconductor laser element 33 serving as a hologram forming light source includes a photodiode 34 for monitoring the optical output and an A.
It is driven by a DC drive circuit with a PC function to have a constant light output. A part of the light emitted from the semiconductor laser element 33 is radiated on a liquid crystal shutter panel 32 of a variable light transmittance type, and each liquid crystal cell 32a is controlled according to a control electric signal input to the liquid crystal shutter panel 32.
Every 32 hours, light having a predetermined transmittance becomes light for forming a hologram and is transmitted.

The laser light radiated on the liquid crystal shutter panel 32 of the variable transmittance type is controlled by the shutter panel 3.
The individual liquid crystal cells are controlled by controlling the voltage applied to the liquid crystal shutter panel 32 based on the correction amount stored in the external memory so that the intensity non-uniformity due to the location on the two surfaces is corrected. The transmittances of 32a to 32h are adjusted in advance.

In the present embodiment, the pinholes 31a and 31g are located in plane symmetry with the optical fiber connection terminals 2a and 2g with respect to the SLM array plate 1.
The liquid crystal cells 32a and 32g provided in close contact with each other are controlled so as to have optical transparency, and the pinholes 31a and 3g are controlled.
The hologram forming lights U and V that have passed through 1 g are emitted to the address space 4 between the pinhole array plate 31 and the SLM array plate 1.

The two hologram forming lights U and V emitted to the address space 4 are irradiated on the optical address side 1D surface of the SLM 1a while interfering with each other, and a light-dark pattern due to the interference is formed on the surface. You.

As described above, when the hologram-forming lights U and V are emitted from the two pinholes 31a and 31g of the pinhole array plate 31, one of the pinholes 3a and 31g is used.
If the complex amplitude of the hologram-forming light U from 1a is represented by A and the complex amplitude of the hologram-forming light V from the other 31g is represented by B, then the two hologram-forming lights U and V are superposed. The intensity I of the resulting light is
It can be expressed by an equation.

I = | A | ² + | B | ² + A ^* · B + AB ^* (2) where * represents a conjugate complex number.

The liquid crystal panels 1a to 1d according to the present embodiment are arranged such that a voltage of a predetermined frequency is applied to the transparent electrodes 14a and 14b.
2 is irradiated with light, the electric resistance changes in proportion to the light intensity I of the irradiated portion, and the orientation angle of the liquid crystal molecules of the liquid crystal layer 13 on the back side changes the voltage change between the two transparent electrodes 14a and 14b. It changes according to. A polarizing glass plate 18 is attached to the surface of the liquid crystal layer 13, and light incident on the liquid crystal layer 13 from the liquid crystal layer surface side 1C is reflected at a reflection intensity according to the orientation angle of the liquid crystal molecules at the incident position. . In this example, a predetermined write voltage is applied to one liquid crystal panel 1a of the SLM array plate 1, and the address space 4
Addressing by light for hologram formation from the side is enabled.

The amplitude reflectance r of the light of the liquid crystal surface 1C with respect to the writing light intensity I on the address surface 1D of the liquid crystal panel 1a is represented by the following equation (3).

R = k ₀ + k ₁ I (3) where k ₀ and k ₁ are constants depending on the characteristics of the liquid crystal panel. Further, the above three equations can be expressed by using the complex amplitude of light for forming a hologram. The following four equations are obtained.

R = k ₀ + k ₁ | A | ² + K ₁ | B | ² + k ₁ A ^* · B + k ₁ A · B ^* (4) As described above, light for forming a hologram is formed on the SLM array plate 1. Of the two-dimensional light-dark distribution generated by the interference between U and V, the portion irradiated on the SLM 1a in the addressable state is recorded as a reflectance distribution on the back surface, and a hologram is formed.

On the other hand, at this time, on the optical signal connection space 5 side, an optical signal X having the same wavelength (1.3 μm) as the semiconductor laser light of the address light source is input from the optical fiber connection terminal 2a, and the liquid crystal layer of the liquid crystal panel 1a is input. The side 1C is illuminated. Each pinhole 31 of the pinhole array mask 31
The positions of a to 31h and the positions of the optical fiber connection terminals 2a to 2h connected to the optical input / output terminal plate 21 are plane-symmetric with respect to the SLM array plate 1, and the address surface side 1D of the SLM panel plate 1 Of the light intensity I of the liquid crystal layer 1
C, the complex amplitude of the optical signal X input from the optical fiber connection terminal 2 a in the optical signal connection space 5 is plane-symmetric with respect to the SLM array plate 1. The intensity R of the reflected light Y with respect to the optical signal X incident from the optical fiber connection terminal 2a on the liquid crystal layer surface 1C of the SLM 1a is equivalent to the complex amplitude A of the hologram forming light U emitted from the pinhole 31a. It becomes an expression.

R = A · r = Ak ₀ + Ak ₁ | A | ² + Ak ₁ | B | ² + k ₁ | A | ² · B + k ₁ A ² · B ^* (5) k ₁ | A | ² · B is the SLM array plate 1
The above shows the first-order diffracted light. The reflected light Y is
The first-order diffracted light k ₁ | A | ² · B of the reflected light Y exists in the optical signal connection space 5 and has a constant value k ₁ | A
| ² is only attenuated. This complex amplitude B is equivalent to the complex amplitude B of the hologram forming light V emitted from the pinhole 31g,
In the optical signal connection space 5, the pinhole 31g and the SLM 1
The light that converges on the optical fiber connection terminal 2g located at a plane symmetric position with respect to a is shown. That is, the optical signal X emitted from the optical fiber connection terminal 2a to the liquid crystal panel 1a
Causes reflection and diffraction on the surface of the liquid crystal panel 1a, and the first-order diffracted reflected light converges on the optical fiber connection terminal 2g and is connected to a predetermined optical path.

On the other hand, the diffracted light of the 0th order and its vicinity represented by the first to third terms of the above equation (5) is expressed by the fifth term of the same equation.
The first-order diffracted light is also reflected by the liquid crystal panel 1a toward the light input / output terminal plate 21 and returns. However, the zero-order light and diffracted light in the vicinity thereof do not converge to a specific point, and the -1st-order light is Since the light is not condensed at the point where the optical fiber connection terminal is installed, the connection of the optical signal does not occur except for the predetermined optical path.

[0039] Here, the ratio of the light intensity I _in input to the optical fiber connection terminal 2a in the intensity I _out of first order diffracted light for focusing onto the optical fiber connection terminal 2g, i.e. the diffraction efficiency η is for hologram formation The following six equations are represented by functions of the intensities of the light U and V.

[0040] _{η = I out / I in =} [k · 2 {(I A · I B) / (I A + I B)} 1/2] 2 ... (6) where, k: depends on the characteristics of the SLM constant I _a: the intensity of light U emitted from the pinhole 31a (=
| A | ²⁾ I _B: light V emitted from the pinhole 31g intensity (=
| B | ² ) The intensity I _out of the light output from the optical fiber connection terminal 2g is expressed by the following equation (7).

[0041] _{I out = η · I in =} [k · 2 {(I A · I B) / (I A + I B)} 1/2] 2 · I in ... (7) light U and for hologram formation strength of V I _a and I _B, i.e. the liquid crystal cell 3 corresponding to the pin hole 31a and 31g
By appropriately controlling the transmittance of 2a and 32g with an externally applied voltage, the optical fiber connection terminal 2
The intensity I _out of the light output from g can be controlled.

In the above, the case where the optical signal from the optical fiber connection terminal 2a is connected to the optical fiber connection terminal 2g has been described.
By changing the position of the aperture 2 and its transmittance by electrical means, it is possible to connect the reflected light of the optical signal X from the SLM array plate 1 to another optical fiber connection terminal or not to connect it at all. It can be done easily. Further, the intensity of the reflected light can be easily changed.

Therefore, in the optical switch configured as described above, a hologram formed by interference of light is used as an element for deflecting and condensing an optical signal to connect the optical signal to an arbitrary optical path. Since a hologram recording medium uses a spatial light modulator having a liquid crystal layer as a recording medium, the resolution of the hologram is limited by the size of the matrix electrode as in the conventional method of electrically forming a hologram pattern on a matrix drive liquid crystal panel. It is possible to increase the resolution up to the characteristics of the liquid crystal itself without receiving the same. For example, in the above embodiment, the resolution is about 250 lines / mm, and a resolution 160 times or more that of a conventional matrix drive liquid crystal (1.5 lines / mm) is obtained.

As a result, the deflection angle (diffraction angle) with respect to the light having a wavelength of 1.3 μm is reduced from the conventional value of about 0.1 degree to 1 degree.
Although it is possible to increase the size to about 9 degrees, an optical system for forming a hologram for writing connection information to the liquid crystal panel is required. Substantial miniaturization by reducing the distance from the plate 2 becomes possible without using auxiliary means such as a lens system.

Further, in the present invention, the hologram recorded on the liquid crystal panel is formed optically, and the electric circuit for forming a hologram, which has been conventionally required, becomes unnecessary.

As described above, according to the present invention, it is possible to provide an optical switch which does not require a small physical connection line and which can easily switch an optical signal path by an electric signal.

Further, although the description has been omitted in the above embodiment,
Since a plurality of liquid crystal panels as a medium for recording holograms are used, if different hologram patterns are recorded on each liquid crystal panel in a time-division manner, a combination of optical path connections according to the number of holograms is performed in parallel. It is also possible. In addition, in addition to switching the optical path of an optical signal by an external electrical signal, it is possible to control the intensity of the optical signal or to control the amount of attenuation, and to perform parallel signal connection or the like with weighting in optical calculation. It is also advantageous for applications.

In addition, in the above embodiment, since the liquid crystal panel is used as the spatial light modulator, writing with hologram forming light from the address side is possible only when a predetermined voltage is applied. Can hold written information by applying different voltages to the liquid crystal panel. Also, by applying a predetermined voltage different from the information holding state,
The written information can be erased. This gives 2 × 2S
After applying a write voltage to an arbitrary liquid crystal panel of the LM array plate 1, for example, the liquid crystal panel 1a, and writing connection optical path information using the address optical system 3, the liquid crystal panel 1a
Is changed to the information holding voltage, the writing voltage is applied to the other liquid crystal panels 1b to 1d, and the opening position of the liquid crystal shutter panel 32 of the address optical system 3 and the transmittance thereof are changed to obtain another connection optical path information. To other liquid crystal panels 1b-1
By writing different connection optical path information to individual SLM cells in a time-division manner by writing to d, independent connection path information can be written to each liquid crystal panel of the SLM array plate 1. In addition, the optical path connection of up to four sets, which is the number of liquid crystal panels, can be performed independently and simultaneously.

In the above embodiment, four liquid crystal panels are used. However, the present invention is not limited to this, and can be implemented using any number of liquid crystal panels as long as it is one or more. .

In the above embodiment, the SLM array plate 1 composed of a liquid crystal panel is used, but the present invention is not limited to this, and other spatial light modulation elements can be used.

In the above embodiment, the number of hologram forming lights used is two. However, the present invention can be practiced with three or more light beams. Equations 2 to 7 hold true.

Further, in the above embodiment, one optical signal X for one input is connected to one output point. However, the present invention is not limited to such a one-to-one correspondence, and the present invention is not limited to one-to-one. Multiple outputs or multiple outputs can be connected to one output, and multiple inputs can be connected to multiple outputs.

Further, in the above embodiment, the optical fiber connection terminal is connected to the optical input / output means. However, the present invention is not limited to this. Of course, the present invention can also be applied to a structure in which a semiconductor laser array or a light receiving element array is arranged on the optical input / output terminal plate instead of the optical fiber connection terminal.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

[0055]

As described above in detail, according to the present invention, since the spatial light modulation element is used, the resolution of the hologram can be improved, whereby the deflection angle can be increased. Considering that the size of the optical system for forming the hologram for writing the connection information is added, the size can be significantly reduced without using auxiliary means such as a lens system. Further, the hologram is formed optically, and the electric circuit for generating the hologram, which has been conventionally required, becomes unnecessary. Therefore, miniaturization and simplification can be achieved, and further, high integration can be achieved. Also,
Since the optical signal is incident and reflected, the optical signal is connected through a reciprocating optical path, so that it is not necessary to increase the diffraction angle of the hologram so much. Use efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical switch according to an embodiment.

FIG. 2 is a front view showing a pinhole array mask provided in the optical switch according to the embodiment.

FIG. 3 is a sectional view showing a liquid crystal panel provided in the optical switch according to the embodiment.

FIG. 4 is an operation explanatory diagram of the optical switch according to the embodiment.

FIG. 5 is a perspective view showing a configuration of a conventional optical switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 SLM array board 1a-1d Liquid crystal panel 2 Optical input / output optical system 2a-2h Optical fiber connection terminal 3 Address optical system 4 Address space 5 Optical signal connection space 21 Optical input / output terminal board 31 Pinhole array mask 31a-31h Pinhole 32 Variable transmittance liquid crystal shutter panel 32a to 32h Liquid crystal cell 33 Semiconductor laser element 34 Photodiode 12 Photoconductive layer 13 Liquid crystal layer 14a, 14b Transparent electrode 15 Dielectric reflection film 16 Light shield 17 Glass plate 18 Polarized glass plate 19 Power supply

Claims (3)

(57) [Claims] 1. A reflective spatial light modulating element for recording a hologram having a pattern determined by the voltage application and the intensity of irradiation light, and a plurality of reflective spatial light modulating elements provided on one side of the spatial light modulating element and having mutual coherence. light for the hologram formation is irradiated to the spatial light modulator, a light generation means for recording a hologram in the spatial light modulator to which a voltage is applied, is provided on the other side sandwiching the spatial light modulator, the An optical input / output means for inputting an optical signal toward the hologram recorded on the spatial light modulator and receiving an optical signal reflected from the hologram ; the light generating means comprising a single light source; Variable transmittance type
Liquid crystal shutter panel consisting of a number of liquid crystal cells
And the light for forming each hologram is generated from the light source.
Each liquid crystal cell of the liquid crystal shutter panel formed from the reflected light
And irradiates the spatial light modulator through the liquid crystal cell.
By changing the transmittance, each hologram is formed.
Optical switch that corrects the non-uniformity of the light intensity . 2. A hologram comprising a plurality of said spatial light modulating elements, wherein said light generating means irradiates each spatial light modulating element with light for forming a hologram in a time-division manner and independently records individual holograms. claim but that for each recorded the respective spatial light modulator, and simultaneously irradiated a plurality of signal light from the light output means, for processing in parallel and simultaneously the number of optical signals corresponding to the spatial light modulator 2. The optical switch according to 1. 3. The light generating means generates light from the light source.
The hologram is formed by splitting the holograms.
Pinhole arrayer with multiple pinholes for mounting
A mask formed by the pinhole array mask.
The intensity of the light for forming each of the holograms is changed by the liquid crystal shutter.
For each liquid crystal cell of the touch panel
Item 3. The optical switch according to item 1 or 2 .