JPH07104522B2 - Spatial light modulator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to optical information processing technology, and more particularly to a spatial light modulator that performs analog parallel processing and display of moving / still images.

(Prior Art) In recent years, as a device capable of processing and displaying optical information such as an image, a spatial light modulator capable of high-resolution and high-speed response is expected.

As one of the conventional spatial light modulators, there is a ferroelectric liquid crystal spatial light modulator shown in FIG. 9, which is "character recognition using LAPS-SLM (1): optical writing type ferroelectric liquid crystal". "Light valve" was published in the proceedings "27a-ZF-2" of the Technical Lecture Meeting of the Japan Society of Applied Physics held in the fall of 1989.

As shown in the figure, the ferroelectric liquid crystal spatial light modulator 1 includes a glass layer 2, an ITO electrode layer 3, and hydrogenated amorphous silicon (a-Si: a-Si:
H) It has a single-layer photoconductive layer 4, an alignment film layer 5, a liquid crystal layer 6, an alignment film layer 5, an ITO electrode layer 3 and a glass layer 2, and a liquid crystal layer is provided between the alignment film layers 5 and 5. The spatial light modulator has a laminated structure in which 6, spacers 7 and 7 are interposed. Here, the ITO electrode layer
A photoconductive layer 4 and a liquid crystal layer 6 are present between 3 and 3.

Further, as another spatial light modulator, there is a reflective spatial light modulator shown in FIG. 10, which is the same as the “reflective spatial light modulator (I) using a liquid crystal composite and a BSO crystal”. Published in the preliminary paper "28p-ZD-6".

As shown in the figure, the reflective spatial light modulator 8 includes ITO electrode layers 9 and Bi in order from the left side of the figure where the writing light Pw enters.
₁₂ SiO ₂₀ (BSO) photoconductive crystal layer 10, dielectric multilayer mirror layer 11, liquid crystal composite layer 12 made of polymer and nematic liquid crystal, ITO electrode layer 9, glass layer 13 It is a spatial light modulator. Here, the photoconductive crystal layer 10 and the liquid crystal composite layer 12 are present between the ITO electrode layers 9 and 9.

(Problems to be Solved by the Invention) However, both the photoconductive layer 4 of the hydrogenated amorphous silicon single layer of the conventional spatial light modulator 1 and the BSO photoconductive crystal layer 10 of the spatial light modulator 8 are both provided. Since the electrophotographic sensitivity (hereinafter sometimes abbreviated as sensitivity) in the long wavelength region of the writing light Pw (incident light) is small, the intensity of the writing light Pw must be increased, but the intensity of the writing light Pw is increased. Then, there is a problem that the contrast of the obtained read image is lowered.

Although not shown here, it has a laminated structure similar to that of the conventional spatial light modulators 1 and 8 described above, and the photoconductive layer 4 of hydrogenated amorphous silicon single layer and the photoconductive crystal of BSO. When a photoconductive layer having a structure different from that of the layer 10 (for example, a photoconductive layer formed by stacking a hydrogenated amorphous silicon layer and another photoconductive layer) is used, a boundary surface is generated between these two layers, so that the writing light is written. As a result of a decrease in the mobility of charges generated inside the photoconductive layer according to Pw, the response speed of the spatial light modulator becomes small, and there is the problem that a fast-moving subject cannot be continuously and clearly processed. It was

(Means for Solving the Problems) Therefore, in order to solve the problems of the above-described conventional techniques, the present invention provides a spatial light modulator having the following configurations (1) to (5).

(1) Spatial light modulation including a laminated structure of a photoconductive member layer, a dielectric mirror layer, and a light modulation material layer between a writing light side transparent electrode layer and a reading light side transparent electrode layer. And at least hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide are used as the photoconductive member layer, and the composition of the junction between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuously changed. A spatial light modulator characterized by being made.

(2) As the photoconductive member layer, hydrogenated amorphous silicon is sandwiched by hydrogenated amorphous silicon carbide, and the composition of two junctions between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuously changed. The spatial modulator according to (1) above, characterized in that

(3) Spatial light modulation including a laminated structure of a photoconductive member layer, a dielectric mirror layer, and a light modulation material layer between the writing light side transparent electrode layer and the reading light side transparent electrode layer. The photoconductive member layer is formed by sequentially stacking hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon, and hydrogenated amorphous silicon carbide as the photoconductive member layer from the transparent electrode layer side on the writing light side. Spatial light modulator.

(4) As the photoconductive member layer, a four-layer structure of hydrogenated amorphous silicon carbide, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon, and hydrogenated amorphous silicon carbide is formed by joining to the transparent electrode layer on the writing light side. The above (3) characterized in that
The spatial light modulator according to.

(5) As the photoconductive member layer of the spatial light modulator according to (3), the composition of the first junction between the hydrogenated amorphous silicon germanium and the hydrogenated amorphous silicon is continuously changed, A spatial light modulator characterized in that the composition of the second junction between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuously changed.

(Example) Hereinafter, a spatial light modulator according to the present invention will be described with reference to FIGS. 1 to 8.

FIG. 1 is a block diagram of an embodiment of a spatial light modulator according to the present invention, and FIGS. 2, 3, and 6 to 8 are photoconductive members of the spatial light modulator shown in FIG. 1, respectively. The layer 18 of the first embodiment, the second embodiment, the third embodiment to the fifth embodiment of the configuration diagram, FIG. 4 is a photoconductive member layer 18 of the spatial light modulator of the configuration shown in FIG. The figure which shows the spectral sensitivity curve which compared the spectral sensitivity of what used the amorphous silicon single layer, and the spectral sensitivity of what laminated hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide as shown in FIG. 2 and FIG. 5 is a photoconductive member layer of the spatial light modulator shown in FIG.
It is a figure for explaining the composition of 18.

Now, as shown in FIG. 1, the spatial light modulator 14 of the present invention has an antireflection film layer 15a, a glass layer 16a, and a transparent electrode layer 17a on the writing light side in order from the left side of the drawing where the writing light Pw enters. ,
The photoconductive member layer 18, the dielectric mirror layer 19, of which the electric resistance value changes only by the incidence of the writing light Pw, which is an essential part of the present invention,
A light modulation material layer 20 composed of a polymer-liquid crystal composite film in which nematic liquid crystal is dispersed in a polymer material, a transparent electrode layer 17b on the readout light side, a glass layer 16b, an antireflection film layer 15b.
Is a spatial light modulator having a laminated structure in which is laminated. Pr
Is the reading light.

The photoconductive member layer 18, which is the main part of the present invention described above, in the figure,
It faces the light modulation material layer 20 via the dielectric mirror layer 19, and each outer surface of the photoconductive member layer 18 and the light modulation material layer 20 has a transparent electrode layer 17a on the writing light side and a transparent electrode layer on the reading light side. Closely joined to 17b. An AC power supply V ₀ is applied to the transparent electrode layer 17a on the writing light side and the transparent electrode layer 17b on the reading light side.

As the photoconductive member layer 18 which is the main part of the present invention described above, as will be described later, a hydrogenated amorphous silicon layer 18b and a hydrogenated amorphous silicon carbide layer (18a) 18c are used, and a hydrogenated amorphous silicon layer 18b and hydrogen are used. The composition of the junction (18d) 18e with the amorphous silicon carbide layer (18a) 18c is continuously changed.

In the first embodiment of the photoconductive member layer 18 described above, the hydrogenated amorphous silicon layer 18b is sandwiched by the hydrogenated amorphous silicon carbide layers 18a and 18c as shown in FIG. 18
Junction portion 18d between a and hydrogenated amorphous silicon layer 18b
In the portion surrounded by the broken line a and the broken line b in the figure, the broken line a
To the broken line b, x in Si _1- xCx of hydrogenated amorphous silicon carbide (a-Si _1- xCx: H) is 0.1 <x
The composition of the hydrogenated amorphous silicon carbide layer 18a and the hydrogenated amorphous silicon layer 18b in the junction portion 18d is continuously changed by continuously changing from a constant value in the range of <0.5 to 0. ing.

Similarly, hydrogenated amorphous silicon carbide layer 18c
18e between the hydrogenated amorphous silicon layer 18b and
In (the portion surrounded by the broken line d and the broken line c in the figure), the broken line d
From the fixed value in the range of 0.1 <x <0.5 to 0 continuously toward the broken line c from the hydrogenated amorphous silicon carbide layer 18c at the junction 18e. And the composition of the hydrogenated amorphous silicon layer 18b are continuously changed.

That is, the above-mentioned value of x of the hydrogenated amorphous silicon carbides 18a and 18c in the above-mentioned photoconductive member layer 18 changes as follows. That is, the value from the junction with the transparent electrode layer 17a on the writing light side to the broken line a is 0.1 <x <0.5.
A constant value within the range of, the value gradually decreases from the broken line a to the broken line b and becomes 0 on the broken line b. The value between the broken line b and the broken line c is 0, and the value gradually increases from the broken line c to the broken line d, and becomes a constant value within the range of 0.1 <x <0.5 on the broken line d, which is constant until the junction with the dielectric mirror layer 19. Is the value of.

As a result, it is possible to obtain a composition in which the ratio of carbon in hydrogenated amorphous silicon carbide gradually decreases from the broken line a to the broken line b (broken line d to broken line c), while the ratio of silicon gradually increases. .

Further, the structure of the second embodiment of the photoconductive member layer 18 shown in FIG. 3 is, as described above, the hydrogenated amorphous silicon layer 18
The hydrogenated amorphous silicon carbide layer 18c of b is used, and the composition of the joint portion 18e between the hydrogenated amorphous silicon layer 18b and the hydrogenated amorphous silicon carbide layer 18c is continuously changed. The same components as those described above are designated by the same reference numerals and the description thereof will be omitted.

Here, the above-mentioned value of x of the hydrogenated amorphous silicon carbide layer 18c in the above-mentioned photoconductive member layer 18 changes as follows.

That is, the value from the junction with the transparent electrode layer 17a on the writing light side to the broken line c is 0, and the value gradually increases from the broken line c to the broken line d, and a constant value within the range of 0.1 <x <0.5 in the broken line d. Is a constant value up to the junction with the dielectric mirror layer 19.

As a result, it is possible to obtain a composition in which the ratio of carbon in the hydrogenated amorphous silicon carbide gradually decreases from the broken line d to the broken line c, while the ratio of silicon gradually increases.

Now, next, the spatial light modulator 14 shown in FIG.
Writing and reading of optical image information by using will be described.

As shown in FIG. 1, an alternating voltage V ₀ is applied in advance between the transparent electrode layer 17a on the writing light side and the transparent electrode layer 17b on the reading light side to apply a uniform electric field to the light modulation material layer 20. Form.

First, writing of optical image information will be described.

When the writing light Pw corresponding to the optical image information of a subject (not shown) is irradiated from the upper surface of the antireflection film layer 15a on the left side in the figure, the writing light Pw is transparent to the antireflection film layer 15a, the glass layer 16a, and the writing light side. After sequentially passing through the electrode layer 17a, the light enters the photoconductive member layer 18. Thus, the electric resistance value of the photoconductive member layer 18 changes corresponding to the optical image by the writing light Pw, and the writing light in the photoconductive member layer 18 is provided on the dielectric mirror layer 19 side in the photoconductive member layer 18. A charge layer corresponding to the incident light (optical image) reaching the transparent electrode layer 17a side is formed. Then, an electric field having an intensity distribution corresponding to this charge image is transmitted to the light modulation material layer 20 through the dielectric mirror layer 19, and the optical axis direction of the molecules of the nematic liquid crystal of the light modulation material layer 20 is transmitted according to this intensity distribution. Changes.

Therefore, the optical image information is converted by the light modulation material layer 20 as a change in the optical axis direction of the molecules of the nematic liquid crystal.

Next, reading of optical image information will be described.

When the reading light Pr is irradiated from the upper surface of the antireflection film layer 15b on the right side in FIG.
6b, after sequentially passing through the transparent electrode layer 17b on the read light side, is incident on the light modulation material layer 20, where the incident light passes according to the change in the optical axis direction of the molecules of the nematic liquid crystal in each part. After that, the dielectric mirror layer 19 is irradiated. The dielectric mirror layer 19 totally reflects this irradiation light, retraces the optical path of the above-mentioned incident light as optical image information light, and then emits it from the antireflection film layer 15b on the right side in the figure. A slight amount of light that is not reflected by the dielectric mirror layer 19 passes through this and passes through the photoconductive member layer 18
The dielectric mirror layer of the photoconductive member layer 18
Since the hydrogenated amorphous silicon carbide layer 18c formed on the 19 side is completely shielded from light, the photoconductive member layer 1
8 does not proceed to the hydrogenated amorphous silicon layer 18b, and the electric resistance value of the photoconductive member layer 18 does not change due to projection of the reading light Pr, and the dielectric mirror layer in the photoconductive member layer 18 does not change. It does not change the charge image formed on the 19 side.

Therefore, the optical image information converted as a change in the optical axis direction of the molecules of the nematic liquid crystal can be read out as optical image information light.

FIG. 4 shows a case where the photoconductive member layer 18 of the spatial light modulator configured as shown in FIG. 1 is a single layer of hydrogenated amorphous silicon,
6 is a spectral sensitivity curve in which electrophotographic sensitivities in the case of stacking hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide are relatively compared.

As is clear from the figure, the sensitivity of the photoconductive member layer 18 formed by laminating hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide shown by the solid line is the hydrogenated amorphous silicon single layer shown by the broken line (improving the volume resistivity. Therefore, the peak of the relative sensitivity is larger than that in the case of a trace amount of boron doped), and the peak wavelength is also shifted to the long wavelength side. Thus, as the writing light Pw, light having a long wavelength at which the above-mentioned peak of sensitivity is large (for example, light of 650 nm to 750 nm) is used, and the reading light Pr is used.
As the light, light having a wavelength which does not pass through the hydrogenated amorphous silicon carbide layer 18c on the side of the dielectric mirror layer 19 (for example, light of 500 nm to 600 nm) is used.

This prevents the read light Pr from changing the charge image in the hydrogenated amorphous silicon layer 18b when reading the optical image information. Therefore, the photoconductive member layer 18 in which the hydrogenated amorphous silicon layer 18b and the hydrogenated amorphous silicon carbide layers (18a) 18c shown by the solid line are laminated
The spatial light modulator 14 using can have high resolution, high contrast, high sensitivity, and fast response speed.

Next, a method of manufacturing the photoconductive member layer 18 will be described.

The photoconductive member layer 18 shown in FIG. 2 and FIG.
The plasma CVD method using glow discharge is used. Hydrogenated amorphous silicon carbide 18a (18c) uses SiH ₄ , C ₂ H ₂ , and H ₂ as raw material gases and hydrogenated amorphous silicon.
For 18b, SiH ₄ and H ₂ were used as the source gas, and the hydrogenated amorphous silicon carbide (a-Si ₁ ) was formed at the junction 18d (18e) between the hydrogenated amorphous silicon carbide 18a (18c) and the hydrogenated amorphous silicon 18b. _- xCx: H Si of)
_{The part of 1-} xCx where the value of x changes continuously is C ₂ H ₂ , H ₂
It can be manufactured by continuously changing the gas flow rate.

Thus, the spatial light modulator 14 shown in FIG. 1 can be manufactured.

Therefore, when the spatial light modulator 14 is incorporated into a device and put into practical use, a semiconductor laser can be used to downsize the device and obtain better sensitivity than conventional ones.

That is, currently, a semiconductor laser can obtain a high output only in a region of 700 to 800 nm or more, and has a low output at a wavelength that does not reach this region, but as described above, it has high sensitivity at a wavelength of light of 650 nm to 750 nm. Therefore, even if a semiconductor laser is used, it is possible to obtain better sensitivity than conventional ones.
Further, the device can be downsized.

Further, the mobility of charges generated in the photoconductive member layer 18 when the writing light Pw is irradiated is one of the factors that determine the response speed of the spatial light modulator. As shown in FIG. Although the presence of the interface where the different members in the member layer 18 are directly bonded reduces the mobility of charges in the photoconductive member layer 18, the photoconductive member layer 18 of the spatial light modulator 14 of the present invention is shown. In the above, since the composition between the members is continuously changed like the joint portions 18d and 18e, a high response speed is realized while maintaining high sensitivity in the long wavelength region.

Next, third and fourth embodiments of the photoconductive member layer 18 of the spatial light modulator 14 shown in FIG. 1 will be described with reference to FIGS. 6 and 7.

The spatial light modulator 14 thus configured has a photoconductive member layer 18, a dielectric mirror layer 19, and a light modulator material layer 20 between the transparent electrode layer 17a on the writing light side and the transparent electrode layer 17b on the reading light side. A spatial light modulator having a laminated structure of, as the photoconductive member layer 20, sequentially from the transparent electrode layer 17a side of the writing light side, hydrogenated amorphous silicon germanium 18g,
It is a spatial light modulator characterized by stacking hydrogenated amorphous silicon 18h and hydrogenated amorphous silicon carbide 18i.

The third embodiment of the photoconductive member layer 18 shown in FIG. 6 has a hydrogenated amorphous silicon carbide layer (a-Si _1- xCx: H) (0.1 < x <0.
5) 18f, hydrogenated amorphous silicon germanium layer (a
-Si _1- yGey: H) (0.3 <y <0.7) 18g, hydrogenated amorphous silicon 18h, hydrogenated amorphous silicon carbide layer (a-Si _1- xCx: H) (0.1 <x <0.5) 18i It is a structure.

Further, the structure of the fourth embodiment of the photoconductive member layer 18 shown in FIG. 7 is such that the hydrogenated amorphous silicon germanium layer 18g, the hydrogenated amorphous silicon layer 18h, and the hydrogenated amorphous silicon germanium layer 18g are bonded to the transparent electrode layer 17a on the writing light side. It has a three-layer structure of an amorphous silicon carbide layer 18i.

Next, writing and reading of optical image information using the spatial light modulator 14 having the photoconductive member layer 18 having the configuration shown in FIGS. 6 and 7 will be described.

As shown in FIG. 1, an alternating voltage V ₀ is applied in advance between the transparent electrode layer 17a on the writing light side and the transparent electrode layer 17b on the reading light side to apply a uniform electric field to the light modulation material layer 20. It is formed and written as in the first and second embodiments.

That is, when the writing light Pw according to the optical image information of the subject (not shown) is irradiated from the upper surface of the antireflection film layer 15a on the left side in the figure, the writing light Pw is the antireflection film layer 15a, the glass layer 16a, and the writing light side. After being sequentially transmitted through the transparent electrode layer 17a, the light enters the photoconductive member layer 18. Thus, the electric resistance value of the photoconductive member layer 18 changes corresponding to the optical image by the writing light Pw,
On the dielectric mirror layer 19 side in the photoconductive member layer 18, a charge image corresponding to the incident light (optical image) reaching the transparent light electrode layer 17a side on the writing light side in the photoconductive member layer 18 is formed. . Then, an electric field having an intensity distribution corresponding to this charge image is transmitted to the light modulation material layer 20 through the dielectric mirror layer 19, and the optical axis direction of the molecules of the nematic liquid crystal of the light modulation material layer 20 is transmitted according to this intensity distribution. Changes.

Therefore, the optical image information is converted by the light modulation material layer 20 as a change in the optical axis direction of the molecules of the nematic liquid crystal.

Next, reading of optical image information will be described.

When the reading light Pr is irradiated from the upper surface of the antireflection film layer 15b on the right side in the figure, the reading light Pr is emitted from the antireflection film layer 15b and the glass layer 1
6b, after being sequentially transmitted through the transparent electrode layer 17b on the readout light side, the light is incident on the light modulation material layer 20, where the incident light passes according to the change in the optical image direction of the molecules of the nematic liquid crystal in each portion. After that, the dielectric mirror layer 19 is irradiated. The dielectric mirror layer 19 totally reflects this irradiation light, retraces the optical path of the above-mentioned incident light as optical image information light, and then emits it from the antireflection film layer 15b on the right side in the figure. The slight amount of light that is not reflected by the dielectric mirror layer 19 passes through it and passes through the photoconductive member layer 18
The dielectric mirror layer of the photoconductive member layer 18
Since the hydrogenated amorphous silicon carbide layer 18i formed on the 19 side is completely shielded from light, the photoconductive member layer 1
8 does not proceed to the hydrogenated amorphous silicon layer 18h or the hydrogenated amorphous silicon germanium layer 18g, and the electric resistance value of the photoconductive member layer 18 does not change due to the projection of the reading light Pr. It does not change the charge image formed on the side of the dielectric mirror layer 19 in the layer 18.

Therefore, the optical image information converted by the light modulation material layer 20 as a change in the optical axis direction of the molecules of the nematic liquid crystal can be read out as optical image information light.

And since the hydrogenated amorphous silicon germanium used as the above-mentioned photoconductive member layer 18 has higher sensitivity than hydrogenated amorphous silicon in the long wavelength region, the hydrogenated amorphous silicon and the hydrogenated amorphous silicon germanium are When used together, the reading light Pr can be further read by hydrogenated amorphous silicon carbide.
A spatial light modulator having a high contrast and a high sensitivity can be obtained by the effect of preventing the change of the charge image due to the projection of.

The above-described photoconductive member layer 18 is manufactured by, for example, a plasma CVD method using RF glow discharge. Hydrogenated amorphous silicon carbide has SiH ₄ , C ₂ H ₂ , H
₂ , hydrogenated amorphous silicon is SiH as a source gas
_4, using SiH _4, GeH _4, H ₂ and H ₂ as the raw material gas for hydrogenated amorphous silicon germanium, in the boundary member is changed continuously manufactured by by changing the kind of the raw material gas You can

Thus, the spatial light modulator 14 shown in FIG. 1 can be manufactured.

Therefore, when the spatial light modulator 14 is incorporated into a device and put into practical use, a semiconductor laser can be used to downsize the device and obtain better sensitivity than conventional ones.

That is, at present, a semiconductor laser can obtain a high output only in a region of 700 to 800 nm or more and has a low output at a wavelength which does not reach this region, but as described above, hydrogenated amorphous silicon germanium is a hydrogenated amorphous silicon. Since the sensitivity is higher in the long wavelength region than that of the conventional one, it is possible to obtain better sensitivity than the conventional one even if a semiconductor laser is used, and further the device can be downsized.

Generally, in order to improve the sensitivity, it is necessary to increase the light absorption coefficient, and for that purpose, the band gap may be reduced. Hydrogenated amorphous silicon germanium has a band gap of 1.1 to 1.6 eV by changing the mixing ratio of SiH ₄ and GeH ₄ , which is smaller than the band gap of hydrogenated amorphous silicon of 1.7 to 1.8 eV. You can

Therefore, by using hydrogenated amorphous silicon germanium for the photoconductive member layer 18, it is possible to obtain a spatial light modulator having higher sensitivity in the long wavelength region.

Next, a fifth embodiment of the photoconductive member layer 18 of the spatial light modulator 14 shown in FIG. 1 will be described with reference to FIG.

The spatial light modulator 14 shown below is a transparent electrode layer on the writing light side.
A photoconductive member layer is provided between 17a and the transparent electrode layer 17b on the readout light side.
A spatial light modulator having a laminated structure of 18, a dielectric mirror 19, and a light modulation material layer 20, the photoconductive member layer.
As 18, the hydrogenated amorphous silicon germanium layer 18g, the hydrogenated amorphous silicon germanium layer 18h, the hydrogenated amorphous silicon carbide layer 18i are sequentially laminated from the transparent electrode layer 17a side on the writing light side, and the hydrogenated amorphous silicon germanium layer 18g is formed. The composition of the first joint portion 18j between the hydrogenated amorphous silicon layer 18h and the hydrogenated amorphous silicon layer 18h, and the composition of the second joint portion 18k between the hydrogenated amorphous silicon layer 18h and the hydrogenated amorphous silicon carbide layer 18i is changed. It changes continuously.

18 g of the above-mentioned hydrogenated amorphous silicon germanium layer (a-Si _1- yGy: H) and the hydrogenated amorphous silicon layer 18
The first junction portion 18j with h changes the value of y in Si _1- yGy continuously from a constant value in the range of 0.3 <y <0.7 to 0, and the hydrogenated amorphous silicon layer 18h and the hydrogenated amorphous layer 18h. At the second junction 18k with the silicon carbide layer (a-Si _1- xCx: H) 18i, the value of x in Si _1- xCx is
The composition of the hydrogenated amorphous silicon germanium layer 18g and the hydrogenated amorphous silicon layer 18h is changed by continuously changing from a constant value in the range of 0.1 <x <0.5 to 0. If the composition with the silicon carbide layer 18i is continuously changed, the boundary surface (hydrogenated amorphous silicon germanium layer) as shown in FIG.
A boundary surface between 18 g and the hydrogenated amorphous silicon layer 18 h,
The interface between the hydrogenated amorphous silicon layer 18h and the hydrogenated amorphous silicon carbide layer 18i) disappears,
The response speed is improved, and in addition to this effect, the high sensitivity described above is obtained.

Although not shown, the photoconductive member layer shown in FIG.
Also in 18, the interface between the hydrogenated amorphous silicon germanium layer 18g and the hydrogenated amorphous silicon layer 18h and the interface between the hydrogenated amorphous silicon layer 18h and the hydrogenated amorphous silicon carbide layer 18i can be eliminated. is there.

(Effects of the Invention) As described above, the spatial light modulator according to the present invention is configured as described above, and therefore, as compared with the conventional spatial light modulator, high sensitivity, high resolution, and high contrast can be obtained. The
Further, since the composition of the junction between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuously changed, a high speed response can be obtained.

Further, as a photoconductive member layer which is a main part of the spatial light modulator according to the present invention, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon, and hydrogenated amorphous silicon carbide are sequentially laminated from the transparent electrode layer side on the writing light side. By doing so, high sensitivity, high resolution, and high contrast can be obtained.

Further, as a photoconductive member layer that is a main part of the spatial light modulator according to the present invention, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon, and hydrogenated amorphous silicon carbide are sequentially laminated from the transparent electrode layer side on the writing light side. And continuously changing the composition of the first junction between the hydrogenated amorphous silicon germanium and the hydrogenated amorphous silicon, and the composition of the second junction between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide. It is possible to obtain high sensitivity, high resolution, high contrast and high speed response by continuously changing.

Furthermore, since the photoconductive member layer, which is a main part of the spatial light modulator according to the present invention, has high sensitivity, a semiconductor laser can be used, so that an apparatus using the spatial light modulator can be downsized. Is great.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a spatial light modulator according to the present invention, and FIGS. 2, 3, and 6 to 8 are photoconductive members of the spatial light modulator shown in FIG. 1, respectively. First embodiment of layer, second
FIGS. 4A and 4B show the spectral sensitivity of the spatial light modulator having the structure shown in FIG. 1 in which a single layer of hydrogenated amorphous silicon is used as the photoconductive member layer. ,
The figure which shows the spectral sensitivity curve which compared the spectral sensitivity of what laminated hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide, and FIG. 5 explains the structure of the photoconductive member layer of the spatial light modulator shown in FIG. Figure to do, No. 9
Figures and 10 are diagrams showing a conventional spatial light modulator. 14 …… Spatial light modulator, 15a, 15b …… Anti-reflection film layer, 16a, 1
6b: glass layer, 17a: transparent electrode layer on the writing light side, 17b
...... Transparent electrode layer on the reading light side, 18 …… Photoconductive member layer, 18
a, 18c, 18f, 18i …… Hydrogenated amorphous silicon carbide, 18b, 18h …… Hydrogenated amorphous silicon, 18g…
… Hydrogenated amorphous silicon germanium, 18d, 18e,
18j, 18k …… Joint part, 19 …… Dielectric mirror layer, 20 ……
Light modulator layer, Pw …… writing light, Pr …… reading light.

Claims (5)

[Claims] 1. A space formed by laminating a photoconductive member layer, a dielectric mirror layer, and a light modulation material layer between a transparent electrode layer on the writing light side and a transparent electrode layer on the reading light side. An optical modulator, wherein at least hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide are used as the photoconductive member layer, and the composition of the junction between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuous. A spatial light modulator characterized by being changed to. 2. As the photoconductive member layer, hydrogenated amorphous silicon is sandwiched by hydrogenated amorphous silicon carbide, and the composition of two junctions between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuous. The spatial light modulator according to claim 1, characterized in that 3. A space provided with a laminated structure of a photoconductive member layer, a dielectric mirror layer, and a light modulation material layer between a writing light side transparent electrode layer and a reading light side transparent electrode layer. An optical modulator, wherein as the photoconductive member layer, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon, and hydrogenated amorphous silicon carbide are sequentially laminated from the transparent electrode layer side on the writing light side. And a spatial light modulator. 4. As the photoconductive member layer, hydrogenated amorphous silicon carbide, hydrogenated amorphous silicon germanium, bonded to the transparent electrode layer on the writing light side,
4. The spatial light modulator according to claim 3, wherein the spatial light modulator has a four-layer structure of hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide. 5. The composition of the first junction between the hydrogenated amorphous silicon germanium and the hydrogenated amorphous silicon is continuously changed as the photoconductive member layer of the spatial light modulator according to claim 3. A spatial light modulator, wherein the composition of the second junction between the hydrogenated amorphous silicon and the hydrogenated amorphous silicon carbide is continuously changed.