JP2828370B2 - Optical neural computer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention also relates to an optical neural computer, in particular, constituting the optical neural computer
Effective combination of transparent substrate with light propagation path between main components
In addition, the integrated structure of the electric circuit and electric wiring is reduced.
It relates to an optical neural computer .

[0002]

2. Description of the Related Art In recent years, researches on optical neural computers, which combine optical parallel processing and neural computing, have been actively conducted at academic societies and the like. FIG. 10 is a configuration diagram of a conventional type optical neural computer forming a typical associative memory. This optical neural computer is a model in which each output signal of a neuron is subjected to threshold processing and then fed back to affect each input signal of the neuron. Finally, the function of this feedback signal causes each input signal to converge to a specific output signal determined by the spatial light modulator.

The configuration of a conventional optical neural computer will be described with reference to FIG. In this optical neural computer, output light L _IN from a light emitting element array 101 in which three LED elements are arranged in a vertical direction is converted into a 3 × 3 matrix spatial light modulator 102 located in the output light traveling direction.
And undergoes modulation. The spatial light modulator is composed of an optical mask manufactured so that the light transmittance of each matrix component is different, and modulates the intensity of transmitted light.

The spatial light modulation element can be realized by, for example, an element comprising a fixed pattern mask formed by metal deposition on a glass plate, or a variable pattern element using ferroelectric liquid crystal. Next, the modulated output light L _OUT from the spatial light modulation element 102 is received by a light receiving element array 103 in which three light receiving elements are arranged in a horizontal direction. A signal obtained by photoelectric conversion by each light receiving element of the light receiving element array 103 is input to three comparators 104, where it is subjected to an electrical threshold process, and each output signal is a binary signal. The conversion signal is fed back to the input of the light emitting element array 101.

In this configuration, the light receiving element array 103
The portion from to the light emitting element array 101 via the comparator 104 corresponds to the connection between input and output to the neuron, and the blinking state of the light emitting element array 101 indicates the excitation from each neuron output input to the neuron. This corresponds to a signal indicating a state. On the other hand, the light transmittance of each matrix component of the spatial light modulator 102 corresponds to the synaptic connection strength of the neural computer.

Here, each light emitting element output light L _IN , p (p = 1,2,3) of the light emitting element array 101 is a component T pq of a matrix p row of each matrix component Tpq of the spatial light modulator 102.
The directivity of each element of the light emitting element array 101 is widened so as to uniformly input to p1, Tp2, and Tp3, and the spatial arrangement is appropriately designed.

Similarly, of the matrix components Tpq of the spatial light modulator 102, the components T1q and T2 of the q-th column of the matrix
q, each output light L _OUT , 1q, L _OUT , 2 from T3q (q = 1,2,3)
q, L _{O UT,} 3q takes wide directivity of the light receiving elements to receive light in a uniform sensitivity light receiving element with one q-th column of the light receiving element array 103, the spatial arrangement and properly designed I have.
(However, miniaturization is limited in this design.)

Next, a signal obtained by photoelectric conversion in the light receiving element array 103 is subjected to threshold processing in each comparator 104 and fed back to an input of the light emitting element array 101. The corresponding process is performed electrically.

To supplement the function of the entire optical neural computer, first, a certain imperfect input signal is input to the light emitting element array 101. By optically repeating the vector-matrix operation and the threshold value processing, The most similar information is selected from the complete information stored in advance in the pattern of the spatial light modulator 102 in some form or the like, and the complete output is obtained as the blinking state (binary signal) of the light emitting element array 101. (Reference: Optics Vol. 17, No. 11, November 1988, p. 552, "Neurocomputer").

[0010]

However, in the above neural computer, Even if the design of the relative spatial arrangement of the light receiving and emitting element array and the spatial light modulator and the design of the directivity of the light receiving and emitting element are optimized, the input light intensity to the spatial light modulator element matrix component and each output light sensitivity It is not easy to align. In addition, when these optimized designs are performed, the dimensions of the entire device also become large in terms of shape. 2. Since the light from the light receiving element array to the light emitting element array via the comparator is not converted to light and electrical wiring is required, integration and integration are complicated. There was a problem. An object of the present invention is to solve the above disadvantages.

[0011]

SUMMARY OF THE INVENTION The present invention provides an input signal light.
A light emitting element array that receives and emits surface light;
Sky having a matrix component that modulates each output light from b
And an output light from the spatial light modulator.
Optical logic operation element
Ray and each output light from the light emitting element array
Guides and separates each matrix component of the light modulator.
A first transparent substrate having a light propagation path for input / output;
Combining the respective output lights from the spatial light modulator to form the optical logic
A second transmission line having a light propagation path for guiding the operation element array;
Light substrate and each output light from the optical logic operation element array.
Guidance is provided to the light emitting element array as feedback signal light
A third transparent substrate having a light propagation path
It is a neural computer.

In the present invention, the light emitting element array is used.
B) may be composed of a surface emitting semiconductor laser array
preferable. In addition, the first transparent substrate, the second transparent substrate
Each optical propagation path of the substrate and said third transparent substrate, a diffraction grating, a total reflection mirror, any one or more of the beam splitter
It is preferable to be formed by an optical element consisting of the above. Ma
The first transparent substrate, the second transparent substrate, and the
Each light propagation path of the third transparent substrate has one annular light propagation.
The light emitting element array and the air
Light modulation element, the optical logic operation element array and each of the
A transparent substrate is created in a shape that can be laminated or bonded.
It is preferable that they are formed integrally. In addition, the optical logic
The arithmetic element array is driven by the input light from the spatial light modulator.
The threshold-processed feedback signal light is transmitted through the third transmission line.
Output to the light emitting element array via the light propagation path of the light board.
Preferably.

[0013]

According to the present invention , a light emitting element array, spatial light modulation
First to third transparent elements and an optical logic operation element array
Each light propagation path of the board is provided, and each light branch
Path, optical coupling path, and feedback optical path.
Therefore, the optical neural computer has each component
, Which facilitates integration and miniaturization. further,
Usually provided between optical logic operation element array and light emitting element array
The electrical feedback circuit is connected to the third transparent substrate.
The optical path can be used as a feedback path.
You. This eliminates the need for electrical circuits and electrical wiring ,
Basically, since it has a simple structure of electrical wiring connected to each electrically active element , the optical neural computer
Integration and integration becomes easier.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an external perspective view of an optical neural computer according to the present invention, in which a surface-emitting type semiconductor laser array 11, a spatial light modulator 13, and incident light from the surface-emitting type semiconductor laser array 11 are applied to the spatial light modulator 13. A first transparent substrate 12 serving as a light propagation path and a branch path for guiding the light, a plurality of output lights from the spatial light modulator 13 are combined, and a second transparent substrate 14 serving as the propagation path is provided. 45 ° total reflection prism 15 that bends the direction of output light from transparent substrate 14 at right angles and propagates it, optical logic operation element array 16 for light detection and threshold processing, and a surface emitting type The third transparent substrate 17 serving as a light propagation path to the semiconductor laser array 11 is a component thereof, and these are laminated or laminated from each direction to form an integrated structure. (In FIG. 1, the thickness of the integrated substrate is shown large, but in practice one transparent substrate may be considered to be about 1 mm thick (total thickness of about several mm).

Next, the operation principle of the optical neural computer according to the present invention will be described. FIG. 2 is an exploded view of each optical element. The details will be described using the drawings of the respective parts shown in FIGS.

First, the light output from the surface emitting semiconductor laser array 11 is obliquely incident on the first transparent substrate 12 as shown in FIG. 3, and propagates in the horizontal direction while repeating internal reflection. However, a reflection mirror made of a metal film or the like is formed so that the propagating light is totally reflected on the transparent substrate side surface 31. On the opposite transparent substrate side surface 32, one-third of the light output is transparent each time the output light is applied. The light is emitted from the substrate 12 in the direction of the spatial light modulator 13.

As shown in FIG. 4, for example, as shown in FIG. 4, on the transparent substrate side surface 32, a diffraction grating 33 or the like having a controlled diffraction efficiency or the like is formed at three positions where light strikes, thereby forming one third of the total light output. Each of them has a structure in which light is emitted from the transparent substrate 12 in the direction of the spatial light modulator 13, or a thin film in which the transmittance, the reflectance, etc. are optimized instead of the diffraction grating 33 is formed as a beam splitter to reduce the total light output. A structure can be adopted in which each third light is emitted from the transparent substrate 12 in the direction of the spatial light modulator 13.

As a result, light of uniform intensity enters each matrix component of the spatial light modulator 13. Next, similarly to the conventional example, the spatial light modulator 13 can modulate the intensity of light, for example, an element consisting of a fixed pattern mask formed by metal deposition on a glass plate, or a variable pattern element using ferroelectric liquid crystal. Things can be used.

In a variable pattern element using a ferroelectric liquid crystal, the switching speed is about 10 ⁻⁶ sec. When high-speed processing is required, AlGaAs / GaAs MQW (Mu
A switching speed of about 10 ⁻¹⁰ sec can be realized by using a spatial light modulation element in which a modulator utilizing the QCSE effect of an ltiQuantum well (CTI) effect and a CCD (Charge Coupled Device) are combined.

The modulated light is emitted from each component of the 3 × 3 matrix. As shown in FIG. 5, the three components in the vertical direction are combined on the next second transparent substrate 14 to form one optical signal. Becomes That is, in each of the second transparent substrates 14 extending in the vertical direction, the diffraction gratings 33 and the like are formed at three arrival positions of the emitted light from the respective components of the matrix of the spatial light modulator 13, and the second transparent substrate 14 is formed. The light is taken into the inside of the transparent substrate 14 and propagated to a predetermined position by reflection inside the transparent substrate 14 while being coupled. At this time, the diffraction grating 33 is designed so that the diffraction efficiency and the like are controlled to be optimum, respectively, so that each light output incident from three places is equally weighted.

In the example shown in FIG. 2, in the right part of the transparent substrate 14, all of the combined optical outputs from three places
Downward, the central portion of the transparent substrate 14 transmits the same total light output to the central portion of the transparent substrate 14, and the left side portion of the transparent substrate 14 transmits the same total light output to the upper portion of the transparent substrate 14. Each diffraction grating 33 is designed so that diffracted light can be obtained.

On the surface opposite to the surface on which the diffraction grating 33 is formed, an exit window 41 (having a transmittance of 100
%), A reflecting mirror is formed by metal film deposition or the like.

The light emitted from each light extraction port of the transparent substrate 14 is transmitted to the 45 ° total reflection prism 1 in the next path.
5, the optical path is bent by 45 degrees, propagates to the end face of the 45-degree total reflection prism 15, enters the optical logic operation element array 16 provided on the end face of the prism, and the light intensity detection and the light intensity are constant. If this is the case, it is a signal binarized by the optical output, such as "1", if it is less than a certain value, "0".

As an example of the optical logic operation element, as shown in FIG. 7, there is an integrated element in which the photodetector and the semiconductor laser are monolithically made of the same kind of material (for example, InGaAsP type) as shown in FIG. Electrically, as shown in FIG. 8, a photodetector 85 and a semiconductor laser 84 are connected in series,
A configuration in which the photodetector 85 receives the output light 86 from the semiconductor laser in addition to the incident light 82 and applies a positive feedback corresponding to the size thereof (reference document: IEEE)
Trans. Electron Devices, ED-31, 805/811 (1984)).

Next, a signal of light intensity corresponding to "0" and "1" of the binary signal is incident on the third transparent substrate 17, and the reflection is repeated inside the transparent substrate 17, and the transparent substrate 17 Propagate to the edge. Then, an optical signal is emitted from the other end of the transparent substrate 17 and becomes a feedback signal light returning to the surface-emitting type semiconductor laser array 11.

A diffraction grating or an input / output window made of a thin film is provided at a position where light enters and exits from the surface of the third transparent substrate 17, and a reflection mirror made of a metal film or the like is formed at an internal reflection position. The surface-emitting type semiconductor laser array 11 emits light itself (light-emitting output PL) by the drive current Iop. At this time, each of the surface-emitting type semiconductor laser arrays 11 according to the magnitude PI of light input from the outside to each element of the array. The magnitude of the threshold current of the element can be reduced by ΔIth, thereby realizing a structure in which, at the same drive current Iop, the output light from each element of the surface-emitting type semiconductor laser array increases by PI and becomes PL + PI.

FIG. 6 shows the driving current versus light output characteristics of each element of the surface emitting semiconductor laser array. Thereby,
Equivalently, the signal itself emits light by an input signal to the optical neural computer, and the feedback signal light is
The element can be regarded as a structure that is apparently transmitted and the sum of the emission intensity and the transmission intensity is input to the spatial light modulator 13.

Using the concept of the equivalent structure, an example of the structure of the semiconductor laser device which can be employed in the surface emitting semiconductor laser array 11 shown in FIG. 9 will be described below. n-
Cladding layer (n-GaAlAs) on GaAs substrate 97
96, an active layer (p-GaAs) 95, a cladding layer (n-
AlGaAs) 94, buffer layer (p-AlGaAs)
93 and a contact layer (p-GaAs) 92 are sequentially laminated, and a p-impurity diffusion region 89 is formed at the center thereof.

An electrode 91 is formed on the upper surface of the contact layer 92 except for a portion opposed to the p-impurity diffusion region 89 at the center, and an output window provided with an AR coat 99 is provided on the opposed portion. On the other hand, the n-GaAs substrate 97 has a thinner substrate at a portion facing the p-impurity diffusion region 89 at the center, and an AR coat 99 is also provided at this portion to serve as an input window for transmitted light 88 from the outside. , N-GaAs
The other portion of the substrate 97 has a structure in which an electrode 98 is formed.

Only the region including the p-impurity diffusion region 89 at the center has a pn structure, and the current flowing therethrough causes
The laser light emitted from the active layer 95 is emitted toward the output window. The feedback signal light passes through the element from the input window to the output window, and a sum 87 of emission intensity and transmission intensity is obtained from the output window.

In the above embodiment, an optical neural computer using a spatial light modulator composed of 3 × 3 matrix components has been described. However, it is needless to say that a space composed of N × N matrix components (N: natural number) is used. It can be easily analogized that the present invention can be applied to an optical neural computer using a light modulation element.

[0032]

According to the present invention, a light emitting element array, a space
First to third light modulation elements and an optical logic operation element array
Each light propagation path of the transparent substrate of
Function as branch path, optical coupling path, feedback optical path
Because it Rukoto, light neural computer each configuration
Integration and miniaturization by combining elements are facilitated. Further
Usually, between the optical logic operation element array and the light emitting element array
The electric feedback circuit provided is connected to a third transparent substrate.
The feedback light path can be made by the light propagation path of the plate.
Wear. This eliminates the need for electrical circuits and electrical wiring.
Basically, the electrical connection connected to each electrically active element
Since it has a simple structure consisting only of lines , the optical neural computer
Data integration and integration become easier.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an optical neural computer according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view for explaining the operation principle of FIG. 1 separately for each optical element.

FIG. 3 is a first transparent substrate side view showing propagation of incident light due to internal reflection according to the embodiment.

FIG. 4 is a perspective view showing a structure of a first transparent substrate according to the embodiment.

FIG. 5 is a second transparent substrate structure diagram showing coupling and propagation of light inside the transparent substrate according to the embodiment.

FIG. 6 is a characteristic diagram showing a drive current versus light output characteristic of each element of the surface emitting semiconductor laser array according to the example.

FIG. 7 is a structural diagram illustrating an example of an optical logic operation element according to an embodiment.

FIG. 8 is an equivalent circuit diagram of FIG. 7;

FIG. 9 is a structural diagram showing an example of a semiconductor laser device constituting a surface emitting semiconductor laser array according to an embodiment.

FIG. 10 is a structural diagram showing a configuration of a conventional optical neural computer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Surface-emitting type semiconductor laser array 12 1st transparent substrate 13 Spatial light modulation element 14 2nd transparent substrate 15 45 degree total reflection prism 16 Optical logic operation element array 17 3rd transparent substrate

Claims (4)

(57) [Claims] 1. A light emitting element array which receives input signal light and emits surface light, and modulates each output light from the light emitting element array .
That the spatial light modulator having a matrix component, and the optical logic operation element array for detecting and thresholding the output light from the spatial light modulator by the light receiving element, the light emitting element array
Each output light from b is converted to each matrix of the spatial light modulator.
Light propagation path for guiding components and distributing input
A first transparent substrate having
Each output light is combined and guided to the optical logic operation element array.
A second transparent substrate having a light propagation path, and each output light from the optical logic operation element array as a feedback signal light.
And a third transparent substrate having a light propagation path for guiding the light emitting element array. 2. The first transparent substrate and the second transparent substrate.
Each optical channel plate and the third transparent substrate, a diffraction grating, a total reflection mirror, any one or more of the beam splitter
2. An optical neural computer according to claim 1, wherein said optical neural computer is formed of an optical element comprising: Wherein said first transparent substrate, each optical propagation path of said second transparent substrate and said third transparent substrate, one ring
Light emitting element array so as to be connected as
A, the spatial light modulator, the optical logical operation element array,
And a shape in which each of the transparent substrates can be laminated or bonded
2. The method according to claim 1, wherein the first and second parts are integrally formed.
An optical neural computer as described. 4. An optical logic operation element array according to claim 1, wherein
The feedback signal light, which has been subjected to threshold processing by the input light from the modulation element, is transmitted through the light transmission path of the third transparent substrate.
Claims, characterized in that the output to the light emitting element array
An optical neural computer according to claim 1 .