JPH04368696A - High-polymer thin-film laminate and optical bistable element and neuron element - Google Patents

Abstract

PURPOSE:To obtain the optical computing element which has necessary optical switching characteristics, executes processing in parallel at a high speed, and is stable and uniform by alternately laminating >=2 kinds of high polymers contg. specific repeating units in thickness unit above the single molecule in such a manner that the axis of the molecular chains parallels with the substrate surface. CONSTITUTION:A transparent conductive electrode 102 consisting of ITO, SnOX, etc., is provided on a transparent insulating substrate 101 consisting of glass, etc. The high polymer contg. the repeating units expressed by formula (where n>=2, X is >=1 groups of O, S, Se, and Te, Y is an arom. or substd. arom. group, Z is a group contg. an imide ring) is used thereon. The transparent conductive electrode 104 is provided on the high-polymer thin films 103 formed by alternately laminating >=2 kinds of such high polymers in the thickness unit of the single molecular or above in such a manner that the axis of the molecular chains parallels with the substrate 101 surface. The optical computing element which yields exit light 109 obtd. by modulating incident light 108 by an external power source 106, executes the processing at a high speed in parallel and is stable and uniform is obtd. in this way.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a specific polymer thin film laminate, a spatial light modulation element and an optical bistable element used in an optical processing device using the same, and a method for constructing a neural network using optical information. This relates to optical neuron devices.

0002

2. Description of the Related Art In recent years, there have been reports of research and development that utilizes the parallelism, high speed, and multiplicity of light to use light as an information medium in place of arithmetic systems that use electrons as an information medium. On the other hand, in the field of architecture in information processing,
There are many research and development reports on neural networks that incorporate information processing methods performed by neuronal groups for image recognition and ambiguity processing, which conventional Neumann-type calculation methods are weak at. In any field, the key is
An element for electronic information processing This is an element for information processing that replaces a silicon transistor. We have proposed constructing a neural network by using various elements for optical calculation. For example, we have proposed the following as an element that simultaneously performs summation and threshold processing of multiple input information, which are performed in nerve cells (hereinafter referred to as neurons), using parallel processing of light. (1) Neuron device combining an amorphous silicon light-receiving layer and a ferroelectric liquid crystal layer (Japanese Patent Application Nos. 3-001145 and 3-001146). (2) A spatial light modulator that combines a photoconductive polyimide light-receiving layer and a ferroelectric liquid crystal layer (Japanese Patent Application No. 73777/1999). (3) Optical neural network device combining a light-receiving layer and an organic light-emitting device (Japanese Patent Application No. 335909/1999).

The following method has also been proposed as another method. (4) Among currently proposed devices using superlattice semiconductor materials (hereinafter referred to as MQW), for example, SEED
(Self-Electro Optic Eff
ect Device) (Journal of
Applied Physics Letters 45, 1984,
(page 13). This element has a structure in which a constant voltage power supply and a series resistor are connected to a diode including an MQW, and combines the photoelectric effect and the exciton Stark effect.

0004

When constructing a system that can perform parallel operations using light as an information medium, one of the important factors is the light energy required for each operation. Requirements differ depending on the method of optical interconnection between optical processing elements, but in the case of neural networks, optical processing elements corresponding to neurons arranged two-dimensionally on the same plane are optically connected to neurons arranged on another plane. There is a need. When a space is used for optical connection using a lens, a large amount of light energy is dissipated into the space. Therefore, it is desirable to drive the optical arithmetic element corresponding to each neuron with low energy. It is also desired that neurons have the ability to memorize the results of learning by light. From this point of view, the optical elements (1), (2), and (3) that we have proposed all have a light energy of μJ/cm2, which is significantly larger than fJ/cm2 of (4). In addition, optical elements (1), (2), and (3) are functional elements that perform summation and threshold processing in parallel, but for example, they store set values such as threshold values after learning for each neuron. There is no function. On the other hand, (4) has a function of temporarily storing the state, and is also being considered as an optical memory. However, the optical element (
4) is not easy to manufacture, and it is expected that it will be very difficult to construct an optical neural network with a large number of neurons or a massively parallel logic operation system.

[0005] In order to solve the problems of the prior art, the present invention provides a stable and uniform polymer thin film, an optical bistable element, and an optical neuron, which have optical switching characteristics necessary for an optical calculation system and can perform high-speed processing in parallel. The object of the present invention is to provide an optical arithmetic element.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the polymer thin film laminate of the present invention is a thin film in which a polymer layer containing a repeating unit represented by the general formula (Chemical formula 1) is formed. The thin film is characterized in that two or more types of thin films are alternately laminated with a thickness of a single molecule or more so that the molecular chain axis is substantially parallel to the substrate surface.

[0007]

[Chemical formula 1]

Next, the optical bistable device of the present invention is provided with a lower electrode on the substrate, on which a polymer containing a repeating unit represented by the general formula (Chemical formula 1) is arranged so that the molecules are aligned with respect to the substrate surface. 2 with a thickness of more than a single molecule so that the chain axes are substantially parallel.
It includes at least a laminate of polymer thin films alternately laminated in different types, and has a structure in which a transparent electrode is laminated on top.

[0009] In the structure of the optical bistable element, it is preferable that a polymer laminate containing a repeating unit represented by the general formula (Formula 1) and another light-receiving layer are laminated. Next, the photoneuron device of the present invention is provided with a lower electrode on a substrate, and a polymer containing a repeating unit represented by the general formula (Chemical formula 1) is placed on the lower electrode so that the molecular chain axis is substantially aligned with respect to the substrate surface. A polymer thin film laminate in which two or more types of polymer thin films are alternately laminated in units of thickness equal to or larger than a single molecule so that the rays are parallel to each other, and one or more electrodes that are not electrically connected to each other are provided on top of the laminate, and a light-receiving It has a structure in which layers are laminated and a transparent electrode is laminated on top.

In the configuration of the optical bistable device or the optical neuron device, the light-receiving layer is preferably a polymer containing a repeating unit represented by the general formula (Formula 1).

[0011]

[Function] According to the configuration of the polymer thin film laminate of the present invention, the polymer containing the repeating unit represented by the general formula (Chemical formula 1) is a photoconductive polymer and has a photoelectric effect, and
It also becomes possible to form an MQW.

That is, when a polymer containing a repeating unit represented by the general formula (Chemical formula 1) is in a crystalline state in which each molecular chain overlaps closely, the electron orbits between adjacent ones overlap, resulting in an optical absorption edge,
The charge mobility changes significantly (Japanese Patent Application No. 74971/1999). Furthermore, the optical absorption edge of a polymer exhibits different values in its crystalline state depending on the chemical structure of the polymer. The SEED has a structure in which a constant voltage power supply and a series resistor are connected to a diode including an MQW, and combines (1) the photoelectric effect and (2) the exciton Stark effect. The polymer containing the repeating unit represented by the general formula (Chemical formula 1) that we proposed is a photoconductive polymer and has the photoelectric effect (1). On the other hand, MQW is a material that exhibits a quantum effect by growing crystals of two types of semiconductor materials with different optical absorption edges and creating a stacked structure. Typically, different types of semiconductor materials are epitaxially grown alternately in layers every several tens of angstroms. A polymer containing a repeating unit represented by the general formula (Chemical formula 1) can be controlled to form a film on an atomic layer basis by a gas-liquid interface deposition method. Particularly preferably, a thin polymer film with few pinholes can be obtained by laminating the polymer on the substrate surface by the Langmuir-Blodgett method (hereinafter referred to as LB method). Therefore, it is possible to form an MQW by alternately laminating polymer films containing repeating units shown in (Chemical formula 1) having different optical absorption edges and maintaining the crystalline state. In particular, when the polymer is polyimide, it has the following characteristics. (1) The optical absorption edge changes significantly due to the difference in X in the general formula (Chemical formula 1). (2) When only X is changed, the crystal system remains the same, and interspecies crystal growth is easy. (3) A uniform multilayer film can be produced by the gas-liquid interfacial deposition method. (4) The wavelength of input light for optical switching can be changed by selecting Z, Y, and n.

The molecular spacing is typically 5 angstroms, and can be formed by laminating several layers. The optical bistable device operates by the photoelectric effect of the polymer itself and the exciton Stark effect due to the MQW structure of the polymer formed by the above method. A typical device structure is shown in FIG. The device structure can be achieved by simply sandwiching this polymer thin film between transparent electrodes.

[0014] When configuring a neural network,
A representative example of the optical neuron element corresponding to each neuron is shown in FIG. The basic structure is a stack of the above-mentioned polymeric thin film, which serves as a light-switching layer, and a light-receiving layer for realizing light summation upon receiving multiple input light inputs, and a common electrode for collecting generated charges. Note that the light-receiving layer can be similarly formed of a polymer containing a repeating unit represented by the general formula (Formula 1). This light-receiving layer may be formed by other film-forming methods, such as a coating method, a vapor deposition method, or a spin coating method. Therefore, an optical functional element that performs optical summation and threshold processing can be manufactured using a relatively easy method. Furthermore, since it is composed of materials having the same molecular structure, there is no problem peculiar to charge accumulation in the junctions between the layers.

[0015]

Embodiments Examples of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of an embodiment of the optical bistable device of the present invention. The structure of the element is as follows: a transparent insulating substrate 101
transparent conductive electrode 102 (e.g. I
TO, SnOx ), two or more types of polymers containing repeating units represented by the general formula (Chemical formula 1) are alternately prepared in units of thickness greater than a single molecule so that the molecular chain axis is parallel to the substrate surface. A thin polymer film 103 is laminated on the substrate, and a transparent conductive electrode 104 is provided as an upper electrode. Transparent conductive electrodes 102 and 104 are connected to a load resistor 105 and an external power source 106
connected through. When incident light 108 enters from one electrode side, modulated output light 109 exits from the other side.

FIG. 2 shows a cross-sectional view of an example of a light threshold device having a light-receiving layer as the structure of the device. There is a transparent conductive electrode 202 on a transparent insulating substrate 201, and the general formula (
A polymer thin film 203 in which two or more kinds of polymers containing repeating units represented by chemical formula 1) are alternately laminated in units of thickness equal to or larger than a single molecule so that the molecular chain axis is parallel to the substrate surface.
are laminated, and further a light-receiving layer 204 is laminated. A transparent conductive electrode 205 is provided as the upper electrode. Transparent conductive electrodes 202 and 205 are connected via an external power source 206. Light incident from the electrode 205 on the light-receiving layer side is absorbed by the light-receiving layer 204 and consists of a control light 207 that is optically modulated by a voltage drop and an input light 208 that is modulated. Modulated output light 209 is emitted from the electrode 202 . Polymer layer 20
A dielectric layer for light reflection may be provided between the light-receiving layer 204 and the light-receiving layer 204 . In this case, the input light 208 is the output light 209
Similarly, the light is incident from the electrode 202.

FIG. 3 shows a cross-sectional view of an embodiment of a photoneuron device having neuron electrodes in which transparent conductive electrodes are electrically independently arranged on a light-receiving layer. A transparent conductive electrode 302 is provided on a transparent insulating substrate 301, and a polymer containing a repeating unit represented by the general formula (Chemical formula 1) is deposited to a thickness of at least a single molecule so that the molecular chain axis is parallel to the substrate surface. Two or more types of polymer thin films 303 are stacked alternately in units of . Neuron electrodes 304 are provided on this layer. Furthermore, a light-receiving layer 305 is laminated. A transparent conductive electrode 306 is provided as the upper electrode. Charges generated in the light-receiving layer on each neuron electrode are collected by a large number of control lights 307, and a voltage is applied to the polymer thin film 303 according to the sum of the light input intensity. As a result, input light 308 is modulated by polymer layer 303 and output as output light 309. The neuron electrode may be a transparent conductive film or a metal layer that also serves as a reflective layer.

Examples of polymers containing repeating units represented by the general formula (Formula 1) include the following where Y in the general formula (Formula 1) is aromatic or substituted aromatic. Benzene, anthracene, naphthalene, pyrene, perylene,
Condensed polycyclic hydrocarbons such as naphthacene, benzanthracene, benzophenanthrene, chrysene, triphenylene, phenanthrene and substituted derivatives thereof, anthraquinone,
Condensed polycyclic quinones and substituted derivatives thereof such as dibenzopyrenequinone, anthantrone, isoviolanthrone, pyrantrone, metal-free phthalocyanine, copper, lead, nickel,
Metal phthalocyanines containing metals such as aluminum, indigo, thioindigo, etc., and derivatives thereof.

(Chemical formula 2) to (Chemical formula 6) shown below are represented by the general formula (
In chemical formula 1), (X, Y) is (S, benzene ring) (Chemical formula 2), (Se, benzene ring) (Chemical formula 3), (S, Naphthalene ring) (Chemical formula 4), (S, Anthracene ring) ring) of (chemical formula 5
), (S, perylene ring) (Chemical formula 6).

The following (Chemical formulas 7) to (Chemical formulas 13) are examples of carboxylic acid components. 3,3',4,4'-benzophenonetetracarboxylic dianhydride (Chemical formula 7), 3,3'
,4,4'-biphenyltetracarboxylic dianhydride (
Chemical formula 8), 1,1',5,5'-biphenyltetracarboxylic dianhydride (chemical formula 9), naphthalene-1,4,5,8
- Tetracarboxylic dianhydride (Chemical formula 10), naphthalene-2,3,6,7-tetracarboxylic dianhydride (
Chemical formula 11) and perylene-3,4,9,10-tetracarboxylic dianhydride (chemical formula 12).

[0021]

[Case 2]

[0022]

[C3]

[0023]

[C4]

[0024]

[C5]

[0025]

[C6]

[0026]

[C7]

[0027]

[Chemical formula 8]

[0028]

[Chemical formula 9]

[0029]

[Chemical formula 10]

[0030]

[Chemical formula 11]

[0031]

[Chemical formula 12]

The thickness of each polymer thin film is 2 to 20 layers,
The thickness is preferably 4 to 500 angstroms, and after laminating these layers alternately, the total number of layers is 10 to 2000, and the total film thickness is 50 angstroms.
~10,000 angstroms is desirable.

A specific example will be explained below. Example 1 In the optical bistable device shown in FIG.
An ITO film having a thickness of 0.1 to 0.5 μm is formed by sputtering. As the polymer thin film 103, (Chemical formula 2)
Several layers of two types of polymers (Chemical Formula 3) and (Chemical Formula 4) were alternately laminated. In order to form a film by the LB method, the film was formed according to the following procedure. A schematic diagram of the LB method accumulator used for film formation is shown in FIG.

When Y in the general formula (Formula 1) is oxygen, (Formula 2)
) adds a diamine compound and pyromellitic anhydride, which is an aromatic tetracarboxylic dianhydride, to an organic solvent dimethylacetamide in a ratio of 1:1 to polymerize polyamic acid. This polyamic acid is dimethylacetamide, benzene 1
: Dilute to 1 mmol/L with a mixed solvent of 1. On the other hand, LB
To apply the method, polyamic acids are salt-formed with long-chain alkyl amines. That is, N,N-dimethyl-n-
1 m of hexadecylamine (hereinafter referred to as C16DMA) in a mixed solvent of dimethylacetamide and benzene 1:1.
Adjust to mol/L. Immediately before spreading on the air-water interface using the LB method, the ratio of polyamic acid:C16DMA is adjusted to 1:2, and the mixture is spread on the pure water surface. The cumulative conditions of the polyamic acid monomolecular film in the LB method were a surface pressure of 25 dyn/cm, a pulling rate of 3 to 10 mm/min, and a room temperature of 20°C. 20 layers are developed to have a film thickness of 100 angstroms. Finally, the polyamic acid cumulative film is imidized by a chemical imidization method. The substrate is immersed in a mixed solution of acetic anhydride:pyridine:benzene=1:1:3 for 12 hours to form a polyimide cumulative film. Thereafter, the solvent is removed by washing with benzene. Through this procedure, the first layer is formed as a predetermined number of layers.

Next, a predetermined number of polymer layers (formula 3) in which Y is a sulfur atom are laminated as a second layer on the surface of the first layer in the same manner. Subsequently, the third layer returns to the polymer layer (Chemical formula 2) and is laminated again. By repeating this procedure, a superlattice structure can be formed.

As an optical characteristic, the absorption characteristic of the thin polymer film layer 103 is shown in FIG. Structure in which 10 layers of 500 angstroms of LB film of (Chemical formula 2) are sandwiched between 1000 angstroms of coating film of (Chemical formula 1), 10 layers of LB film of (Chemical formula 3) 50
Structures sandwiching 0 angstrom are shown respectively. For comparison, the bulk state is (Chemical formula 2) and (Chemical formula 3) with a coating film of 2000 angstroms. Both of the layered structures formed by the LB film exhibit absorption characteristics unique to a superlattice structure, with carrier confinement due to a well structure and an exciton peak structure at positions where energy jumps. This indicates that a quantum well structure is formed by a polymer thin film. In the figure, absorption peaks between quantized levels corresponding to n=1, 2, and 3 due to the single well structure appear. Also, when (Chemical formula 2) is used as a quantum well, the energy of the first peak is 1.85e
V, the energy of the first peak when (Chemical formula 3) is used as a quantum well is 1.76 eV. This is the general formula (chemical formula 1)
This is because the absorption band changes depending on the heteroatom in the structure, and the more a heteroatom with a larger atomic number is included in the structure, the more the π-electron system develops and the absorption band shifts to the lower energy side. FIG. 6 shows the change in absorption characteristics when the LB film layer thickness of (Chemical formula 2) is changed. The LB film thickness of (Chemical formula 2) was 500 angstroms for 10 layers, 1000 angstroms for 20 layers, and 2000 angstroms for 40 layers. As shown in FIG. 6, the quantum effect becomes more pronounced as the LB layer thickness of (Chemical formula 2) becomes smaller, and the exciton effect is seen because it has a peak rather than a step-like shape. In Figure 7 (Chem. 1)
The absorption characteristics of polymer thin films with different numbers of wells, 3 layers of 15 angstroms and (Chemical formula 3) 10 layers of 50 angstroms, are shown. This shows that as the number of wells increases, the energy barrier of (Chemical formula 1) is exceeded and the levels of the wells interact with each other due to the tunnel effect, causing level splitting.

The optical nonlinear response characteristics of the optical bistable elements formed by these formulas (1) and (2) were investigated. An optical bistable device having the device configuration shown in FIG. 1 was evaluated. First, we looked at the dependence of the absorption characteristics on electric field strength in the case of no load resistance. The optical input wavelength is (
1.85 eV (6
70 nm). FIG. 8 shows changes in absorption characteristics with respect to changes in applied voltage V. As the applied voltage increases, the exciton state changes and the absorption band shifts to the lower energy side. The configuration shown in FIG. 1 is a method for realizing optical nonlinear response characteristics by utilizing changes in response to changes in electric field strength. When the load resistance R and the photoconductive property of the polymer thin film 103 itself are combined, an electric field applied to the polymer thin film itself is shown as the light intensity increases. Shows good threshold characteristics, switching characteristics and bistability. Therefore, it becomes possible to construct a logic circuit using light.

Example 2 In the optical bistable element shown in FIG. 2, the light-receiving layer 204 was
A polymer film was formed using a coating method. The film formation method is based on the crystallization method proposed by us (Patent application No. 2-74971).
issue). The thickness of the light-receiving layer was 2.0 μm. Control light 207
(Chemical formula 3) was used as LED light with a short wavelength of around 550 nm from the photosensitivity wavelength range. FIG. 10 shows the optical response characteristics of the optical bistable element with respect to the optical intensity of the control light. As the control light intensity increases, the threshold value placed on the photoresponse changes. After the control light 207 is blocked, it exhibits a memory characteristic that maintains its transmittance.

Example 3 In the photoneuron device shown in FIG.
Similar to Example 1, a thin film layer having the polymer structures of (Chemical formula 2) and (Chemical formula 3) was formed by the LB method. As the neuron electrodes 303, 6×6=36 ITO transparent electrodes were two-dimensionally arranged in an area of 1 mm 2 on a polymer thin film layer. Furthermore, a polymer coating film similar to Example 1 (Chemical formula 3) was formed as a light-receiving layer. The optical summation function of this device was confirmed using the following method. The control light 207 is green L with a wavelength of around 550 nm.
6×6=36 EDs were turned on to irradiate one neuron electrode, and the response of output light 309 to input light 308 with a wavelength of 670 nm was observed. FIG. 11 shows response characteristics to light intensity for arbitrary combinations of lighting LEDs. As is clear from this, the light sum calculation function is confirmed.

Next, the neural network system shown in FIG. 12 was constructed using this optical neuron element, and an associative memory was constructed. The neural network uses an orthogonal learning method, with an incident image 121 and a microlens array 1.
22, a learning mask pattern 123, and the optical neuron element 124 of this embodiment. Note that the optical neuron element 124
In this study, the neuron electrode was made of an aluminum layer that also served as a reflective layer. The input image 121 displays 10 alphabetic characters in a 6×6 matrix. Each matrix element corresponds to an input signal Xi. This image input uses visible light having a wavelength of 550 nm, and is set to function as control light for the optical neuron element. The learning mask pattern 123 consists of a 36×36 matrix, and is a film whose transmittance is changed so that the 8-gradation display obtained by the orthogonal learning method can be expressed by the intensity of transmitted light. Each matrix element corresponds to a synaptic weight Wij. The input image Xi is multiple-expanded by the microlens array 122, and the image is formed on the learning mask, so the light product calculation Wi
j·Xi is expressed by the transmitted light of the learning mask. The optical neuron element 124 is a 6×6 matrix, and the transmitted light from the 6×6 mask patterns is focused on each pixel by the microlens array 123. In each neuron, the calculation (Equation 1) is performed using the optical summation function of the optical neuron element and the optical nonlinear response.

[0041]

[Math 1]

The final calculation result is output as the distribution of light reflected from the neuron electrode of the readout light. Using this system, the self-recollection of a complete pattern of 10 letters of the alphabet and the association of an incomplete pattern with a Hamming distance of 1 were obtained.
Answered with a recognition rate of %.

[0043]

[Effect of the invention] The polymer containing the repeating unit represented by the general formula (Chemical formula 1) of the present invention is prepared in two types in units of thickness equal to or larger than a single molecule so that the molecular chain axis is parallel to the substrate surface. The above alternately laminated polymer thin films, as well as optical bistable devices and optical neuron devices using the same, have optical switching characteristics necessary for optical processing systems, and are stable and uniform optical processing devices that perform high-speed processing in parallel. It can be done. As a result, a logical arithmetic machine, a neural network, etc. can be configured in the arithmetic system. Furthermore, the polymer thin film of the present invention, and the optical bistable device and optical neuron device using the same, can be used as devices suitable for optical computing systems.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical bistable device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an optical threshold device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a photoneuron device according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of an LB device according to an embodiment of the present invention.

FIG. 5 is an absorption characteristic diagram of polymer thin films with different chemical structures according to Example 1 of the present invention.

FIG. 6 is an absorption characteristic diagram of polymer thin films with different quantum well structures according to Example 1 of the present invention.

FIG. 7 is an absorption characteristic diagram of polymer thin films having different numbers of quantum wells according to Example 1 of the present invention.

FIG. 8 is a diagram showing changes in absorption characteristics of the polymer thin film of Example 1 of the present invention with respect to different applied voltages.

FIG. 9 shows the photoresponse characteristics of the optical bistable device of Example 1 of the present invention.

FIG. 10 is a photoresponse characteristic of the optical threshold device according to Example 2 of the present invention with respect to the light intensity of control light.

FIG. 11 shows the response characteristics of the optical neuron element according to Example 3 of the present invention to the light intensity of control light.

FIG. 12 is a schematic diagram of a neural network circuit according to Example 3 of the present invention.

[Explanation of symbols]

101 Transparent insulating substrate 102 Transparent conductive electrode 103 Polymer thin film 104 Transparent conductive electrode 105 Load resistance 106 External power supply 107 Optical bistable element 108 Incident light 109 Output light

Claims (5)

[Claims] 1. A thin film in which a polymer layer containing a repeating unit represented by the general formula (Chemical formula 1) is formed, the thin film having a molecular chain axis substantially parallel to the substrate surface. A polymer thin film laminate characterized in that two or more types of polymer thin films are alternately laminated with a thickness of more than a single molecule. [Chemical formula 1] -Z-(-X-Y-)n - (However, n≧2 X: At least one group Y selected from O, S, Se, Te: Aromatic or substituted aromatic group Z: group containing an imide ring) 2. A lower electrode is provided on the substrate, and a polymer containing a repeating unit represented by the general formula (Chemical formula 1) is placed on the lower electrode so that the molecular chain axis is substantially parallel to the substrate surface. An optical bistable element comprising at least a laminate of two or more types of polymer thin films alternately laminated with a thickness of a single molecule or more, and a transparent electrode laminated on top. [Chemical formula 1] -Z-(-X-Y-)n - (However, n≧2 X: At least one group Y selected from O, S, Se, Te: Aromatic or substituted aromatic group Z: group containing an imide ring) 3. The optical bistable device according to claim 2, wherein the polymer laminate according to claim 1 and another light-receiving layer are laminated. 4. A lower electrode is provided on the substrate, and a polymer containing a repeating unit represented by the general formula (Chemical formula 1) is placed on the lower electrode so that the molecular chain axis is substantially parallel to the substrate surface. A polymer thin film laminate in which two or more types of polymer thin films are alternately laminated in units of thickness equal to or larger than a single molecule, one or more electrodes that are not electrically connected to each other is provided on top of the laminate, and a light-receiving layer is further laminated. A photoneuron device with a transparent electrode layered on top. [Chemical formula 1] -Z-(-X-Y-)n - (However, n≧2 X: At least one group Y selected from O, S, Se, Te: Aromatic or substituted aromatic group Z: group containing an imide ring) 5. The optical bistable device or optical neuron device according to claim 3, wherein the light-receiving layer is a polymer containing a repeating unit represented by the general formula (Formula 1).