WO2004097507A1

WO2004097507A1 - Optical coupling element, photo-refractive element having the same, and optical information processing device

Info

Publication number: WO2004097507A1
Application number: PCT/JP2004/003926
Authority: WO
Inventors: Takafumi Sassa; Tetsuya Aoyama; Tatsuo Wada
Original assignee: Riken
Priority date: 2003-03-25
Filing date: 2004-03-23
Publication date: 2004-11-11
Also published as: JPWO2004097507A1; JP4675778B2

Abstract

There is provided an optical coupling element for realizing a photo-refractive element having an excellent operability and functionality and capable of easily and effectively generating light interference fringes in a photo-refractive medium. A photo-refractive element having the optical coupling element and an information processing device are also disclosed. The optical coupling element consists of a trapezoid-shaped prism having an incident plane set at a predetermined inclination with respect to the write light incoming into the photo-refractive medium and is arranged on at least one side of the photo-refractive medium. The photo-refractive element arranges the optical coupling element on at least one side of the photo-refractive medium. The information processing device includes the photo-refractive element having the optical coupling element arranged on at least one side of the photo-refractive medium.

Description

Description Optical coupling element, photorefractive element provided with the same, and optical information processing device

The present invention relates to an optical coupling element, a photorefractive element including the same, and an optical information processing apparatus. More particularly, the present invention relates to an optical coupling element suitable for use in a photorefractive element and a photorefractive element including the same. The present invention relates to an element and an optical information processing apparatus, and more particularly, to an optical coupling element capable of easily and efficiently generating optical interference fringes in a photorefractive medium constituting a photorefractive element, and an optical coupling element including the optical coupling element. The present invention relates to a photorefractive element and an optical information processing device. Here, in the photorefractive medium, the transfer of charges generated in the photorefractive medium due to the formation of optical interference fringes in the photorefractive medium is promoted by applying an electric field from the outside, and the photorefractive medium is accelerated. Medium (which is referred to as "external electric field driven photorefractive medium" in this specification) and the diffusion electric field induced in the photorefractive medium without applying an external electric field. A photorefractive medium that enhances the photorefractive effect by promoting Electric Driven Photorefractive Medium " I do. ) Is known. In this specification, the external electric field driven photorefractive medium and the internal electric field driven photorefractive medium are collectively referred to simply as “photorefractive medium”.

In this specification, a photorefractive element using an external electric field driven photorefractive medium is referred to as an “external electric field driven photorefractive element”. The term “internal electric field driving type photorefractive element” shall be referred to as “the internal electric field driving type photorefractive element”. Generally, a material having a glass transition temperature near room temperature, lower or higher than room temperature is used as an external electric field driven photorefractive medium, while an internal electric field driven photorefractive medium is used as an external electric field driven photorefractive medium. Glass transition temperature well above room temperature Use of the material. BACKGROUND

In general, in order to increase the performance of the photorefractive effect in a photorefractive element, a grid of optical interference fringes formed in a photorefractive medium by irradiating two photons to the photorefractive element is required. It is known that a larger electric field (effective driving electric field) needs to be applied in the vector direction. That is, the effective driving electric field is applied in the lattice vector direction of the optical interference fringes. This is because the response amplitude can be increased and the response speed can be increased.

When two writing lights are irradiated on the photorefractive element, optical interference fringes are generated in the photorefractive medium in parallel with the bisector of the two writing lights. Here, FIG. 1 shows a conceptual configuration explanatory view of a conventional external electric field drive type photorefractive element.

The external electric field driven photorefractive element 10 shown in FIG. 1 includes a substantially rectangular external electric field driven photorefractive medium 12, a pair of substantially flat transparent substrates 14 a, 14 b, and It has a pair of substantially flat transparent electrodes 16a and 16b attached to a pair of substantially flat transparent substrates 14a and 14b, respectively. And, between the transparent electrode 16a attached to the transparent substrate 14a and the transparent electrode 16b attached to the transparent substrate 14b, an external electric field driven photorefractive medium 12 is sandwiched. . More specifically, the external electric field-driven photorefractive medium 12 and the transparent electrodes 16a and 16b are defined by the one surface of the rectangular external electric field-driven photorefractive medium 12 and the transparent substrate 1. 4a A substantially flat transparent electrode 16a attached to a is arranged so as to contact the plane of 16a, and the other surface opposing one surface of the rectangular external electric field driven photorefractive medium 12 It is arranged so that the surface of the substantially flat transparent electrode 16b attached to the transparent substrate 14b abuts.

The structure of the external electric field driving type photorefractive element having such a configuration is as follows. It is generally called a sandwich type cell structure.

Reference numeral 18 denotes a power supply connected to the pair of transparent electrodes 16a and 16b, respectively, for applying an electric field to the external electric field drive type photoreflective medium 12 from the outside.

Conventionally, in order to irradiate the external electric field drive type photorefractive element 10 with writing light for forming optical interference fringes, one side of the external electric field drive type photorefractive medium 12, for example, as shown in FIG. As shown, two writing lights are irradiated from one transparent substrate 14a side. When the two writing lights are irradiated on the external electric field driven photorefractive element 10, the optical interference fringes are parallel to the bisector of the two writing lights in the external electric field driven photorefractive medium 12. Generated. Note that such an arrangement of the writing light is generally called a tilt arrangement.

In the tilt type arrangement shown in FIG. 1, as described above, two writing lights for forming optical interference fringes are incident from one side of the external electric field driving type photorefractive element 10. In order to apply a driving electric field to the optical interference fringes formed in the electric-field-driven photorefractive medium 12, the lattice vector of the optical interference fringes has a tilt angle 0 with respect to the externally applied electric field vector applied by the T source 18. (90 degrees)

(Tilt) to select the incident angle of the writing light.

In this case, the effective driving electric field applied in the lattice vector direction of the optical interference fringes is given as a cosine component of the externally applied electric field applied by the power supply 18. Therefore, in order to increase the effective driving electric field applied in the lattice vector direction of the optical interference fringes, it is necessary to make the inclination angle 0 as close to 0 as possible. However, the tilt type arrangement shown in FIG. 1 has a problem that the inclination angle 0 cannot be made sufficiently small.

That is, as the inclination angle 0 is reduced, the incident angle of the writing light increases, and therefore, the reflection loss of the writing light on the surface of the transparent substrate 14a increases, and the external electric field driving type photo-reflector is increased. This is because the writing light cannot reach the active medium 12. As a result, the effective driving electric field component cannot be sufficiently increased. Conventionally, the inclination angle 0 is generally used at around 30 °, and in this case, only about 50% of the externally applied electric field can be used as the effective driving electric field. .

Thus, the combination of the conventionally used photorefractive element with a sandwich cell structure and the tilted arrangement of the writing light is a system in which the photorefractive performance cannot be maximized. there were. In view of these problems, a method for maximizing photorefractive performance has been proposed (for example, Japanese Patent Application Laid-Open No. — See page 5 and Figures 1 and 13.) However, the method disclosed in Patent Document 1 does not disclose a specific device that can easily generate optical interference fringes with high operability and functionality and with high efficiency. , Easy to operate, high efficiency There has been a strong demand for a proposal for a method for realizing a photorefractive element capable of generating optical interference fringes in an active medium. The present invention has been made in view of the background of the invention as described above, the problems of the conventional technology, and the demand for the conventional technology, and the object thereof is to provide excellent operability and functionality. To provide a photorefractive element for realizing a photorefractive element capable of generating optical interference fringes in a photorefractive medium with high efficiency, a photorefractive element including the same, and an optical information processing device It is. Disclosure of the invention

In order to achieve the above object, the optical coupling device according to the present invention is, for example, combined with a conventionally used sandwich-type cell structure to form an optical interference fringe optimally arranged in a photorefractive medium. That is, it is possible to easily form the light interference fringes arranged so that the inclination angle 0 becomes 0 ° with high efficiency. In order to achieve the above object, a photorefractive element according to the present invention is one in which a photorefractive element is formed using the optical coupling element according to the present invention.

Furthermore, in order to achieve the above object, an optical information processing device according to the present invention is an optical information processing device configured using the photorefractive element according to the present invention. That is, the present invention comprises a trapezoidal prism having an incident surface set at a predetermined inclination with respect to the writing light incident on the photorefractive medium, and is disposed on at least one surface side of the photorefractive medium. Optical coupling element. Further, the optical coupling device according to the present invention is arranged such that the inclination of the incident surface is adjusted according to the desired period of the optical interference fringe formed in the photorefractive medium by the ## of the writing light to the photorefractive medium. Is set. Further, the present invention is a photorefractive element in which the optical coupling element according to the present invention is disposed on at least one surface side of the photorefractive medium.

Further, in the photorefractive element according to the present invention, the optical coupling element is disposed on one surface side of the substantially rectangular photorefractive medium and on the other surface side facing the one surface side, respectively. One of the two writing lights emitted from a direction perpendicular to the thickness direction of the photorefractive medium and from a mirror image with respect to a plane passing through the center of the thickness is applied to one of the photorefractive media. And the other of the two writing lights is disposed on the other surface of the photorefractive medium facing the one surface of the photorefractive medium. The light enters the incident surface of the optical coupling device.

Further, the present invention includes a two-dimensional encoding device, a spatial modulator control device, a spatial modulator, and a photorefractive element, and inputs an input signal to the two-dimensional encoding device and the spatial modulator. One or both of the two write lights are controlled by the spatial modulator into which the two write lights are input to the spatial modulator through the control device and the two write lights are incident on the photorefractive element. In optical information processing equipment, The optical information processing device is a photorefractive element according to the present invention, wherein the fractive element is a photorefractive element.

Further, in the optical information processing device according to the present invention, the photorefractive element is a photorefractive element according to the present invention, and two write lights to the photorefractive element are controlled by a single spatial modulator. is obtained by way _c Further, the present investigation is 27 and the fire source encoding apparatus, a spatial modulator controller, a spatial modulator, and a photo Refla data revertive element, the two-dimensional input signal The two write lights are input to the spatial modulator through the encoding device and the spatial modulator control device, and the two write lights are incident on the photorefractive element by the spatial modulator. In the optical information processing apparatus for controlling the optical information, the photorefractive element receives two writing lights in a tilt arrangement, and the two-dimensional encoding apparatus and the spatial transformation are used. An optical information processing device that has an oblique image correction circuit between the controller and the controller, and performs image modulation of the two writing lights with a single spatial modulator by correcting the I ^ oblique image correction circuit. It is. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram of a conceptual configuration of a conventional external electric field drive type photorefractive element.

FIG. 2 is a schematic structural perspective view of an external electric field driven photorefractive element as a photorefractive element according to the present invention including the optical coupling element according to the present invention. FIG. 3 is a view (side view) of arrow A in FIG. 2, and corresponds to the drawing shown in FIG. 4A is a perspective view of a prism as an optical coupling element according to the present invention, and FIG. 4B is a view (a side view) of FIG.

FIG. 5 is an explanatory diagram showing the formation of optical interference fringes in the external electric field driving type photorefractive element according to the present invention shown in FIGS.

FIG. 6 is a graph showing an example of the calculation results of the apex angle a on the writing light incident side and the total loss of transmitted light for the external electric field driven photoreflective element according to the present invention.

FIG. 7 is a graph showing experimental results of a two-light-wave coupling experiment using an external electric field driven photorefractive element according to the present invention.

FIG. 8 is an optical information processing apparatus according to the present invention showing an apparatus configuration for performing an optical memory, an image recognition (pattern matching), and a real-time degraded image tally jung which actively uses an optical correlation method as optical information processing.

FIG. 9 shows an optical information processing apparatus according to the present invention, which shows an apparatus configuration for detecting a moving object or real-time amplification of a moving image as optical information processing.

FIG. 10 is an explanatory diagram showing a configuration corresponding to the code C of the optical information processing device according to the present invention shown in FIG. 8 in the conventional optical information processing device.

FIG. 11 is an enlarged view of a main part, in which only the configuration of reference symbol C shown in FIG. 8 is extracted and shown. FIG. 12 is an explanatory diagram showing a main part of a configuration of an optical information processing apparatus using a conventional external electric field driven type photorefractive element having an oblique image correction circuit.

FIG. 13 shows the photorefratiability according to the present invention provided with the optical coupling device according to the present invention. FIG. 4 is an explanatory diagram of an internal electric field driving type photorefractive element as a switching element. FIG. 14 is an explanatory diagram of an external electric field driven type photorefractive element as a photorefractive element according to the present invention including the optical coupling element according to the present invention, which does not include a transparent substrate.

FIG. 15 is an explanatory view of an internal electric field driven photorefractive element as a photorefractive element according to the present invention provided with the optical coupling element according to the present invention, which does not include a transparent substrate.

FIG. 16 shows (a) an external electric field driven photorefractive element as a photorefractive element according to the present invention provided with the optical coupling element according to the present invention, and one surface of an external electric field driven photorefractive medium. FIG. 2 is a schematic perspective view illustrating a configuration in which a prism is provided as an optical coupling element only in FIG. 2B, and FIG. 2B is a view (a side view) of FIG. Explanation of reference numerals

10, 100 External electric field driven photorefractive element

2 External electric field drive type

4a, 14b

6a, 16b transparent electrode

8

102a, 102b prism

04a, 104b Write light incident surface 106 a, 106 b Writing light exit surface

108a, 108b bottom

1 10a, 1 10b Top surface

200, 300 Central control unit

202, 208, 3 02 2D encoder

204, 210, 304 Spatial modulator controller

206, 21 2, 3 06, 502 Spatial modulator

214, 308, 3 10 CCD camera

2 16, 31 2 2D decoding device

218, 220, 3 14 Laser

222, 316 beam separator

224, 226 Half mirror

400a, 400b spatial modulator

DESCRIPTION OF THE PREFERRED EMBODIMENTS 500 Skewed Image Correction Circuit

Hereinafter, with reference to the accompanying drawings, an optical coupling device according to the present invention and a photorefractive device including the same will be described in detail as well as an example of an embodiment of an optical information processing device. In the description of the present specification and the accompanying drawings, the same or corresponding components and contents will be denoted by the same reference numerals, and redundant description of the configuration and operation will be omitted. FIG. 2 is a schematic structural perspective view of an external electric field driving type photorefractive element as a photorefractive element according to the present invention provided with an optical coupling element according to the present invention, and FIG. The view from the arrow A (side view) of 2 is shown (the drawing shown in FIG. 3 corresponds to the drawing shown in FIG. 1).

The external electric field driving type photorefractive element 100 shown in FIG. 2 includes a pair of trapezoidal, more specifically, truncated square pyramid-shaped prisms 102a and 102b as an optical coupling element according to the present invention. This is different from the external electric field driving type photorefractive element 10 shown in FIG.

That is, in the external electric field driving type photorefractive element 100, the trapezoidal prism 102a is arranged on the transparent substrate 14a, while the trapezoidal prism 102b is arranged on the transparent substrate 14b. More specifically, the transparent substrate 14a and the bottom surface 108a of the prism 102a (the prism 102a has a trapezoidal shape in which the area of the bottom surface 108a is larger than the area of the upper surface 110a). The transparent substrate 14b and the bottom surface 108b of the prism 102b (the trapezoid 102b has a trapezoidal shape in which the area of the bottom surface 108b is larger than the area of the upper surface 11 Ob). I have.

Here, FIG. 4 (a) shows a perspective view of the prisms 102a and 102b, and FIG. 4 (b) shows a view from arrow B (side view) of FIG. 4 (a). .

The prisms 102a and 102b have a vertex angle a (α <90 °) on the writing light incident side, and The trapezoidal prism has a trapezoidal side surface with the apex angle / 3 (/ 3 <90 °) on the writing light emission side, the refractive index n, and the base length L as characteristic parameters. That is, the writing light incident surfaces 104a and 104b of the prisms 102a and 102b have inclinations with respect to the bottom surfaces 108a and 108b, and the writing light emitting surfaces of the prisms 102a and 102b. 106a and 106b have a slope of] 3 with respect to the bottom surfaces 108a and 108b.

As a material for forming the prisms 102a and 102b, a solid that is optically transparent and can be cut and polished is used. For example, an inorganic glass or a polymer can be used. More specifically, examples of the inorganic glass include quartz glass, soda-lime glass, borosilicate glass, and lead glass. Examples of the polymer include polymethyl methacrylate, polystyrene, polycarbonate, and polyvinyl carbazole. Here, among the characteristic parameters of the prisms 102 a and 102 b, the apex angle a on the writing light incident side and the apex angle on the writing light emitting side] 3 and the refractive index n are formed in the external electric field driven type photorefractive medium 12. , The transmittance T of the entire external electric field driven type photorefractive element 100, and the optical input / output coupling rate (The optical input / output coupling rate is the writing light incident on the photorefractive element. This indicates the ratio of the power of the light emitted from the photorefractive element to the power.) The relationship between the apex angle on the writing light incident side, the apex angle on the writing light emitting side], the refractive index n, the period of the optical interference fringes, the transmittance of the entire photorefractive element, and the optical input / output coupling ratio After It will be described in detail. In the above configuration, in order to generate optical interference fringes in the external electric field drive type photorefractive medium 12, as shown in FIG. 5, the external electric field drive type photorefractive medium 12 has a thickness t direction. The two writing light beams are applied perpendicularly to the plane and passing through the center of the thickness t from the mirror image to the entrance planes of the prisms 102 a and 102 b. Respectively.

That is, of the two writing light beams emitted from the direction perpendicular to the thickness t direction of the external electric field driven photorefractive medium 12 and from the mirror image with respect to a plane passing through the center of the thickness t. Is incident on the incident surface 104a of the prism 102a, and the other is incident on the incident surface 104b of the prism 102b.

As described above, the two writing light beams are perpendicular to the thickness t direction of the external electric field driven type photorefractive medium 12 and are prisms from the mirror image with respect to a plane passing through the center of the thickness t. When the light is incident on the incident surfaces 104a and 104b of the 102a and 102b, respectively, the two writing lights are refracted by the prisms 102a and 102b. The light enters the external electric field driven photorefractive medium 12 and intersects on a plane passing through the center of the thickness t of the external electric field driven photorefractive medium 12. Then, the two writing light beams that enter and cross the external electric field driven type photorefractive medium 12 cause light interference in the photorefractive medium 12 parallel to the bisector of the two writing light beams. Stripes are formed.

Note that the two writing lights incident on the photorefractive medium 12 are The writing light is incident on prisms 102a and 102b different from the prisms 102a and 102b on which the writing light is incident, and is emitted to the outside from emission surfaces 106a and 106b of the prisms 102a and 102b, respectively.

When the two writing beams respectively incident on the entrance surfaces 104a and 104b of the prisms 102a and 102b are parallel beams, the prisms 102a and 102b have the same characteristic parameters, If “vertical angle _α = vertical angle”, then, as shown in FIG. 5, the two writing lights incident from the emission surfaces 104a and 104b of the prisms 102a and 102b, respectively, are parallel lights. Become.

Here, the two writing light beams are perpendicular to the thickness t direction of the external electric field driven type photorefractive medium 12 and are mirror images of a plane passing through the center of the thickness t. a and 102b are incident on the incident surfaces 104a and 104b, respectively, are refracted by the prisms 102a and 102b, and are incident on the external electric field driven photorefractive medium 12. The direction of the lattice vector of the optical interference fringe generated in the active medium 12 can be made to coincide with the direction of the externally applied electric field vector. Therefore, all of the externally applied electric field can be used for the effective driving electric field. In the method disclosed in Patent Document 1, the direction of the externally applied electric field vector and the direction of the lattice vector of the optical interference fringes can be matched, but the method disclosed in Patent Document 1 Since there is no optical coupling element such as the prisms 102a and 102b, without changing the arrangement of the optical system to which the writing light is incident, 2 It is difficult to set the crossing angle of the book writing light to an arbitrary size, and it is difficult to obtain optical interference fringes at an arbitrary period.

However, as described later, in the photorefractive element according to the present invention including the optical coupling element such as the prisms 102a and 102b, without changing the arrangement of the optical system for entering the writing light, By appropriately selecting the apex angle of the writing light incident side of the optical coupling element, that is, the inclination of the writing light incident surface, an arbitrary crossing angle of the two writing lights, that is, an optical interference fringe having an arbitrary period can be obtained. It can be easily obtained. Next, the apex angle a of the prisms 102 a and 102 b on the writing light incident side, the apex angle on the writing light emitting side, and the refractive index η are determined by the refractive index of the external electric field driven photorefractive medium 12. Correspondingly, it can be set so as to obtain a high optical input / output coupling ratio, for example, an optical input / output coupling ratio of 80% or more.

Here, the period 光 of the light interference fringes obtained with respect to the apex angle a on the writing light incident side is given by the following equation.

Λ = λ (2ncos 0 _in )

Where λ is the wavelength of the light used as the writing light and η is the external electric field drive type The refractive index of the photorefractive medium 1 2, 0 i _n are those shall apply in refraction angle in the external electric field driven Fotori Furakutibu medium 1 within 2 represented by the following formula.

Where α is the vertex angle of the prism 102 a and 102 b on the writing light incident side,

1 ^ is the refractive index of the prisms 102 & 102b.

Next, the entire photorefractive element 100, that is, the photorefractive medium 12, a pair of transparent substrates 14a and 14b, a pair of transparent electrodes 16a and 16b, and a pair of prisms The transmittance T of the photorefractive element 100 having 102 a and 102 b is expressed by the following equation. Here, the transmittance T is equal to the power of the incident light power 1 after passing through the photorefractive element 100 and exiting. T = (1 -R _l ) (1 -R ₂ ) ² (1 -R ₃ )

However,

tan (90—one 0.)

=

tan (90— + 0.)

tan [Qf + θ ₀ — β—sin— ¹ {n _p sin (af + θ ₀ — β)}]

tan [Qf + Θ ₀ — β + sin— ¹ {n sin (+ θ ₀ — β)}]

Here,] 3 is the apex angle of the prisms 102a and 102b on the writing light emission side. The graph shown in FIG. 6 shows that, using the above equation, the period of the optical interference fringe is 0.5 μπ! With respect to the refractive index of 1.70 of the external electric field driven type photorefractive medium 12. 9 shows the calculation results of the apex angle a of the prisms 102a and 102b on the incident side of the writing light and the total loss of the transmitted light, which are calculated to obtain 2.2.0. In the graph shown in FIG. 6, the curves indicated by the solid line (showing the apex angle a on the writing light incident side of the prisms 102a and 102b) and the broken line (showing the total loss of transmitted light) are In both cases, the lower power in the graph is 0.5 μπ in steps of 0.25111! It corresponds to an optical interference fringe period of ~ 2.0 µm. Note that the apex angle of the writing light incident side and the apex angle of the writing light emission side are equal to Assume that It is assumed that the refractive indices of the transparent substrates 14a and 14b and the transparent electrodes 16a and 16b are equal to the refractive indices of the prisms 102a and 102b. In such a case, for example, when forming an optical interference fringe having a period of 1.25 μιη in the external electric field driven photorefractive medium 12, the refractive indexes 11 of the prisms 102a and 10213 are set to 1.690 to 1.737. And the vertex angles of the prisms 102a and 102b on the writing light incident side are 57 ° to 76. By setting the value within the range, the incident light that enters the photorefractive element 100, passes through the photorefractive element 100, and is transmitted light emitted from the photorefractive element, that is, the total loss of the emitted write light is reduced. It can be suppressed to 20% or less, in other words, a high optical input / output coupling ratio of 80% or more can be achieved.

For the base length L of the prisms 102a and 102b, for example, “the refractive index n of the prisms 102a and 102b n = 1.737” and “the apex angle of the writing light incident side of the prisms 102a and 102b” α = 57 ° ”, assuming that the incident light height of the writing light from the transparent electrodes 16a and 16b is 3 mm, the length of the bottom side of the prisms 102a and 102b is L = 27mm. . However, the base length L of the prisms 102a and 102b can be shortened by optimizing the apex angle β on the writing light exit side of the prisms 102a and 102b or adjusting the incident light height of the writing light. Further, the prisms 102a and 102b, that is, the optical coupling element according to the present invention also have the following features.

That is, the period of the light interference fringes is the same as the writing light incident side of the prisms 102a and 102b. It is determined by the value of the term angle, in other words, the inclination of the entrance surfaces 104a and 104b of the prisms 102a and 102b. Therefore, when it is desired to change the period of the light interference fringes, it is sufficient to replace the prism with the apex angle on the writing light incident side set to a desired value. When it is desired to change the period of the optical interference fringes in the conventional photorefractive element 10, it is necessary to finely adjust the incident angle of the write light to the external electric field driven photorefractive medium 12 by a mirror or the like. Was. However, if the optical coupling element according to the present invention is used, it is only necessary to replace the prism with a desired apex angle, and there is no need to change the beam arrangement of the incident light with a mirror or the like. Therefore, by using the optical coupling element according to the present invention, it is possible to construct an optical system having a simple configuration and strong against vibration.

In the case where the optical coupling device according to the present invention is used, the optical interference fringes can be obtained by changing the wavelength of the writing light incident on the optical coupling device without changing the apex angle on the writing light incident side. Can be changed. Next, the results of an experiment performed by the present applicant will be described. The external electric field driven photorefractive element 100 used in this experiment is low as the external electric field driven photorefractive medium 12. A polymer material having a glass transition temperature is used. This polymer material is a multi-component system including polyvinylinole force / levazonole (photoconductive polymer), ((4-piperidylphenyl) methylene) methane-1,1,1-dicarbonitrile (second-order nonlinear dye) Material. Since this polymer material has a glass transition temperature lower than room temperature, it has a large photoreflection effect due to the orientation enhancement effect. A ratatip effect is obtained at room temperature. In addition, it was confirmed that the photorefractive medium 12 formed of this polymer material had a refractive index of 1.'70 ± 0.01 for the writing light of 633 nm used in the experiment. . The photorefractive medium 12 used had a thickness t of 100 / zm.

Glass having a refractive index of 1.77 was used as a material for the prisms 102a and 102b and the transparent substrates 14a and 14b.

The design value of the apex angle a of the prisms 102a and 102b on the writing light incident side was set to 30 °. The value of the apex angle “= 30 °” on the writing light incident side corresponds to a light interference fringe period of 0.5 and a light input / output coupling ratio of 95% or more.

The transparent electrodes 16a and 16b are laminated on one surface of each of the transparent substrates 14a and 14b, and the transparent electrode 16a and the transparent electrode 16b are combined so as to face each other. An external electric field driven photorefractive medium 12 is sandwiched between 6a and the transparent electrode 16b to form a sandwich cell structure.

In addition to using the external electric field driving type photorefractive element 100 having the above configuration, a He-Ne laser with a wavelength of 633 nm is used as a light source, and two writing lights are applied to the external electric field as shown in Fig. 5. The driven photorefractive element 100 was irradiated, and a two-wave coupling experiment was performed.

In this two-light-wave coupling experiment, by observing the change in the output of the writing light transmitted through the external electric field driven type photorefractive medium 12, the photorefractive The effect can be confirmed. That is, the formation of the refractive index diffraction grating based on the photorefractive effect in the external electric field driven photorefractive medium 12 can be confirmed by the generation of the optical interference fringes. When a photorefractive grating is formed, a power shift occurs between the two light waves, and an optical coupling phenomenon occurs in which the power of one increases and the power of the other decreases. The more effectively the photorefractive grating is formed, the greater the amount of power transferred.

Here, the graph shown in FIG. 7 shows the experimental results of the above-described two-light-wave coupling experiment, and the plot indicated by a triangle in the graph shown in FIG. 7 shows the external electric field-driven photovoltaic device according to the present invention. The experimental results of the two-light-wave coupling experiment using the refractive element 100 are shown. On the other hand, the plots indicated by the triangles in the rough shown in Fig. 7 are the conventional external electric-field-driven photorefractor shown in Fig. 1. The results of a comparative experiment of a two-light-wave coupling experiment using a tapip element 10 are shown.

In the graph shown in Fig. 7, after applying ff for a while from the power supply 18, only one write light is transmitted (time t <0), and the other write is performed at "time t = 0". The power change of both writing lights when light is incident is shown. The writing light power was 20 O mWZ cm ² , and the electric field intensity applied by the power supply 18 was 25 V / μm.

As is evident from the graph of FIG. 7, it is clear that the optical interference fringes are formed on the photorefractive medium 12 by irradiating the two writing lights, and at the same time, the apparent movement between the two light waves occurs. Understand (see the 〇 in the graph shown in Fig. 7). In the case of the conventional external electric field drive type photoreflector element 10 shown in FIG. In the case of the external electric field drive type photorefractive element 100 according to the present invention (see the symbol in the graph shown in FIG. 7), the amount of power transfer is larger than that in the symbol (◊ in the graph). .

This result indicates that, in the external electric field driving type photorefractive element 100 according to the present invention, since the optical interference fringe was formed so as to have a lattice vector parallel to the external electric field vector, the external electric field was lost. This is considered to be due to the fact that it could be used for the effective driving electric field without any change. The optocoupler according to the invention is designed to provide an increase in the intensity, phase and interaction length of the internal electric field which determines the photorefratic response. In the photorefractive element provided with the optical coupling element according to the present invention, the electric field necessary for the movement of the photocarrier is supplied to the maximum by the external electric field. Next, an optical information processing apparatus according to the present invention, which includes the photorefractive element according to the present invention including the optical coupling element according to the present invention, will be described.

That is, various optical information processing apparatuses can be manufactured using the photorefractive element according to the present invention including the optical coupling element according to the present invention. Specifically, it is possible to realize an optical information processing apparatus for performing optical information processing such as image recording, image recognition (pattern matching), real-time degraded image talling, moving object detection or real-time amplification of a moving image. .

FIGS. 8 and 9 are schematic diagrams each showing a device configuration for performing the various types of optical information processing described above. FIG. Here, FIG. 8 shows an example of an apparatus configuration for performing image recording, image recognition (pattern matching), and real-time degraded image cleaning using the optical correlation method as optical information processing. On the other hand, FIG. 9 shows an example of an apparatus configuration for detecting moving objects or real-time decoding of moving images as optical information processing.

In the optical information processing apparatus shown in FIG. 8, the input signal output from the central controller 200 is transmitted to the spatial modulator 206 through the two-dimensional encoder 202 and the spatial modulator controller 204. The two write lights are controlled by the spatial modulator 206 into which the two write lights are input to the external electric field drive type photorefractive element 100 and the two write lights are simultaneously input from the central controller 200. The output input signal is input to the spatial modulator 212 via the two-dimensional encoder 208 and the spatial modulator controller 210, and the light incident on the external electric field driven photorefractive element 100 is The result image information obtained by the control can be obtained by inputting to the central control device 200 via the CCD camera 214 and the two-dimensional decoding device 210.

Also, in the information processing apparatus shown in FIG. 9, the input signal output from the central control unit 300 is transmitted through the two-dimensional encoding unit 302 and the spatial modulator control unit 304 to the spatial modulator 3. The input to the external electric field driving type photorefractive element 100 is input to the external electric field driving type photodetector 100 by the spatial modulator 303 into which one of the two writing lights is incident. The writing light is controlled, and the resulting image information obtained can be obtained by inputting to the central control unit 300 through the two-dimensional decoding device 312 by the CCD camera 3108 or the CCD camera 310. . A tunable laser can be used for each of the lasers 218, 220, and 314. In this case, multiplexing at multiple wavelengths is performed without adjusting the optical path in each device. Operation becomes possible.

Reference numeral 222 denotes a beam separator, reference numerals 222 and 222 denote half mirrors, and reference numeral 316 denotes a beam separator.

Here, the optical information processing apparatus shown in FIG. 8 to FIG. 9 described above is a photorefractive element, in place of the conventional external electric field drive type photorefractive element 10 shown in FIG. It differs from the conventional optical information processing apparatus in that an electric field driven photorefractive element 100 is used.

Further, in the optical information processing apparatus shown in FIG. 8, the configuration indicated by reference numeral C is also different from the configuration of the conventional optical information processing apparatus.

That is, in the conventional optical information processing apparatus, the configuration corresponding to the code C of the optical information processing apparatus shown in FIG. 8 is represented by the force shown in FIG. In order to perform information processing, the spatial light modulators 400a and 400b are applied to both of the two writing lights incident on the external electric field driven photorefractive element 10 in a tilt arrangement. Had to be installed.

However, in the optical information processing apparatus according to the present invention using the external electric field driving type photorefractive element 100 according to the present invention, FIG. 11 (FIG. 11 shows only the configuration of reference numeral C shown in FIG. 8). As shown in the figure, parallel light can be made incident as ^two writing lights to the external electric field driven photorefractive element 100, so that one spatial modulator is used. 2 0 6 In addition to performing image modulation, an oblique image correction circuit, which will be described later with reference to FIG. Therefore, the space for the optical arrangement can be saved, and the overall configuration of the optical information processing apparatus can be simplified.

A conventional optical information processing apparatus in which two writing light beams are incident in a tilt type arrangement using an external electric field driven photorefractive element 10 having a conventional sandwich cell structure as shown in FIG. In addition, by incorporating an oblique image correction circuit 500 between the two-dimensional encoding device 202 and the spatial modulator control device 204, two writings can be performed by one spatial modulator 502. It can also serve as light image modulation. Such a configuration can also save the space for disposing the optical system. The above embodiment can be modified as described in the following (1) to (6).

(1) In the above embodiment, the detailed description of the material of the external electric field driven photorefractive medium 12 is omitted, but the material of the external electric field driven photorefractive medium 12 is photoconductive and photoconductive. A material having an electro-optic effect can be used. Such a material can be produced, for example, by mixing or chemically bonding a photoconductive material and an electro-optic effect material. Examples of the photoconductive material include, for example, poly (vinylcarbazole) and poly (vinylenevinylene). Further, by adding a sensitizing dye such as trinitrofluorenone or fullerene to these materials, the light sensitivity can be enhanced. Materials exhibiting the electro-optic effect include, for example, optical second-order nonlinear molecular There are molecules that have anisotropic linear polarizability, such as donor groups such as amino group and methoxy group on azo, stinoleben, and polyene skeletons, and receptor groups such as formyl group and nitro group. Some have a molecular structure combining the above.

(2) In the above-described embodiment, the force s described for the external electric field driven photorefractive medium which requires an externally applied electric field for the appearance of the photorefractive effect.The present invention relates to an external electric field driven photorefractive medium. Of course, it is not limited. That is, the present invention may be applied to an internal electric field driven photorefractive medium in which an externally applied electric field is not required for the expression of the photorefractive effect.

Here, the material shown in the above (1) can be basically used for the internal electric field driven type photorefractive medium, but the material of the external electric field driven type photorefractive medium has a glass transition temperature of room temperature. Alternatively, it must be lower or higher. On the other hand, the material of the internal electric field driving type phototriflate medium is required to have a glass transition temperature sufficiently higher than room temperature. The glass transition temperature can be lowered, for example, by adding a plasticizer such as ethyl carbazole or butylbenzyl phthalate, or by chemically modifying a long-chain alkyl group to the material.

In the case where the photorefractive element according to the present invention is constituted by an internal electric field driving type photorefractive medium, an external electric field is simply applied to the transparent electrodes 16a and 16b as in the above-described embodiment. May not be used, or as shown in Fig. 13, the photoreflector may be used without transparent electrodes. Eve elements may be configured.

(3) In the above embodiment, the transparent electrodes 16a and 16b are provided on the transparent substrates 14a and 14b, but it is needless to say that the present invention is not limited to this. That is, as shown in FIG. 14, the transparent electrodes 16a and 16b are directly disposed on the prisms 102a and 102b, respectively, and an external electrode is provided between the transparent electrodes 16a and 16b. The electric-field-driven photolithographic medium 12 may be sandwiched.

Further, in the photorefractive element according to the present invention using the internal electric field driving type photorefractive medium as shown in FIG. 13, as shown in FIG. 15, the direct reflection between the prisms 102 a and 102 b occurs. An internal electric field drive type photorefractive medium may be sandwiched.

(4) In the above-described embodiment, the prism 102a is provided on one surface of the external electric field driving type photorefractive medium 12, and the prism 102b is provided on the other surface facing the one surface. Thus, the optical coupling elements are provided on both surfaces of the external electric field driven type photorefractive medium 12, but it is a matter of course that the present invention is not limited to this. That is, as shown in FIGS. 16 (a) and 16 (b), an optical coupling element such as the prism 102a may be provided only on one surface of the external electric field driven photorefractive medium 12. Similarly, an optical coupling element such as a prism may be provided on only one surface of the internal electric field driven photorefractive medium.

As described above, one of the external electric field driven photorefractive medium 12 When an optical coupling element such as a prism is provided only on the surface, for example, in the configuration shown in Figs. 16 (a) and (b), one surface of the external electric field driven photorefractive medium 12 For one writing light incident on the prism 102 a as the optical coupling element disposed only for the other, the other writing light is composed of the external electric field driven photorefractive medium 12 and the transparent electrode It is supplied by the reflected light of the one writing light reflected at the interface with 16b. Also in this case, similarly to the above, an optical interference fringe in which the lattice vector and the externally applied electric field vector completely match is formed. Therefore, a photorefractive effect can be generated by one writing light. As described above, when an optical coupling element such as a prism is provided only on one surface of the internal electric field driving type photorefractive medium, for example, only the prism 102 a in the configuration shown in FIG. 13 is used. When the prism 102 b is not provided and the prism 102 b is not provided, the prism 102 a as an optical coupling element provided only on one surface of the internal electric field driving type photorefractive medium is provided. The other writing light is reflected by the interface between the internal electric field drive type photorefractive medium and the transparent substrate 14b with respect to the one writing light incident on the substrate. Supplied by Also in this case, as described above, an optical interference fringe in which the lattice vector and the externally applied electric field vector completely match is formed. Therefore, a photorefractive effect can be generated by one writing light.

(5) Although the detailed description is omitted in the above embodiment, the prisms 102a and 102b can be configured to be detachable from the transparent substrates 14a and 14b. With this configuration, characteristic parameters such as the apex angle α on the writing light incident side Can be easily attached and detached as appropriate.

(6) The above-described embodiment and the modifications shown in (1) to (5) above may be combined as appropriate. Industrial applicability

Since the present invention is configured as described above, an object of the present invention is to realize a photorefractive element which has excellent operability and functionality, and which can easily and efficiently generate optical interference fringes in a photorefractive medium. An optical coupling element or a photorefractive element provided with the optical coupling element has an excellent effect that an optical information processing device can be used.

Claims

The scope of the claims

1. A trapezoidal prism having an incident surface set at a predetermined inclination with respect to the writing light incident on the photorefractive medium, and is arranged on at least one surface 彻 J of the photorefractive medium.

An optical coupling device, comprising:

2. The optical coupling device according to claim 1,

The inclination of the incident surface is set according to a desired period of an optical interference fringe formed in the photorefractive medium by the writing light being incident on the photorefractive medium.

An optical coupling device, comprising:

3. The optical coupling device according to claim 1 or claim 2 is provided on at least one surface of the photorefractive medium.

This is a photorefractive element.

4. The photorefractive element according to claim 3,

The optical coupling element is disposed on one surface side of the warm-cubic photorefractive medium and on the other surface side opposite to the negative surface side,

Perpendicular to the thickness direction of the photorefractive medium; One of the two writing lights emitted from a direction forming a mirror image with respect to a plane passing through the heart is incident on an incident surface of an optical coupling element arranged on one surface side of the photorefractive medium, The other of the two writing lights is projected onto the incident surface of the optical coupling element disposed on the other surface of the photorefractive medium, which is opposite to the one surface of the photorefractive medium.

A photorefractive element, characterized in that:

5. It has a 27-dimensional encoding device, a spatial modulator control device, a spatial modulator, and a photorefractive element, and inputs an input signal through the two-dimensional encoding device and the spatial modulator control device to the space. An optical information processor for controlling one or both of the two writing lights by the spatial modulator, which inputs the two writing lights to the photoreflective element when input to the modulator. In place

The photorefractive element is the photorefractive element according to any one of claims 3 and 4.

An optical information processing apparatus characterized by the above-mentioned.

6. The optical information processing apparatus according to claim 5,

The photorefractive element is the photorefractive element according to claim 4,

Two write lights to the photorefractive element are controlled by a single spatial modulator An optical information processing unit 3 characterized by the above-mentioned.

7. A two-dimensional encoding device, a spatial modulator control device, a spatial modulator, and a photorefractive element, and an input signal is transmitted through the two-dimensional encoding device and the spatial modulator control device to the space. An optical information processing apparatus which controls the two writing lights by the spatial modulator into which the two writing lights are input to the modulator and the photo-reflecting element is input.

The photorefractive element receives two writing lights in a tilted arrangement.

An oblique image correction circuit is provided between the two-dimensional encoding device and the spatial modulator control device, and the two writing operations are performed by a single spatial modulator by correcting the oblique image correction circuit. Performs light image modulation