JP3323533B2 - Hologram recording material, method for manufacturing hologram recording element, and hologram recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photorefractive hologram recording element capable of performing spatial light modulation and real-time hologram recording, a method of manufacturing the same, and a hologram recording method using the hologram recording element.

[0002]

2. Description of the Related Art Conventionally, a photorefractive (photorefractive) effect has been found for inorganic secondary nonlinear optical crystals such as lithium niobate, barium titanate, strontium barium niobate, and bismuth silicon oxide. Have been researched and used as real-time hologram recording elements or phase conjugate elements.

On the other hand, organic second-order nonlinear optical materials have attracted attention in recent years because large nonlinear optical constants are expected. In particular, active studies have been made on the use of such materials as electro-optic modulation elements by laser light wavelength conversion and Pockels effect. I have.

[0004] In addition, a second-order nonlinear optical material, 2
It has been confirmed that an organic crystal obtained by doping tetracyanoquinodimethane (TCNQ) into cyclooctylamino-5-nitropyridine exhibits a photorefractive effect that has been observed only with inorganic crystals (Solid State Communication). Vol. 74, pages 867-870 (K.
Shutter, J. Huliger and P. Gunter Solid State Commun
ics, Vol. 74, No. 8, p867-870, 1990)).

Further, an epoxy polymer of 2,2-bis (4'-hydroxyphenyl) propane diglycidyl ether (so-called diglycidyl ether of bisphenol A) and an epoxy polymer of 4-nitro-1,2-phenylenediamine,
The polymer composition doped with diethylaminobenzaldehyde diphenylhydrazone, which is a photoconductive agent, having a low glass transition temperature was subjected to holographic exposure at a light amount of 13 W / cm ² simultaneously with application of an electric field for promoting the orientation of the nitroaniline portion. The generation of diffracted light in the order of 0.001% was observed (Physical Review Letters, Vol. 66, pp. 1846-1849 (Stephan ducharme, JCScott,
RJTwieg, and WEMoerner Physical Review Letters
66 (14), 1846-1849, (1991)).

[0006]

However, in the case of an inorganic material such as bismuth silicon oxide, it is not easy to obtain a large single crystal, so that it is difficult to manufacture a large-area hologram recording element, and the manufacturing efficiency is low. There was a problem that the element was expensive due to the low height.

On the other hand, in the case of an organic material, it is considered that the hologram recording element may have a large area and a low cost.
-Cyclooctylamino-5-nitropyridine is not practical because of low sensitivity and diffraction efficiency. Further, there is a problem that it is difficult to obtain a hologram recording element having a large area as in the case of an inorganic material, because it is a crystal.

Further, even in the polymer composition, the epoxy polymer non-linear optical material doped with a low-molecular photoconductive material as described above has low solubility of the photoconductive agent and is cured by heating in a polarized state. However, there is a problem in that a large space charge distribution cannot be expected, that is, an increase in diffraction efficiency cannot be expected because the charge generation ability is poor and there is almost no charge trapping.

In order to solve the above problems, the present invention provides a hologram recording material which is an organic material and is an amorphous polymer composition, and it is easy to increase the area using such a material. It is an object of the present invention to provide a hologram recording element having high sensitivity, high diffraction efficiency and stable characteristics, and a method of manufacturing a hologram recording element with high production efficiency and low cost. It is another object of the present invention to provide a hologram recording method for recording a hologram using the hologram recording element of the present invention.

[0010]

In order to achieve the above object, the hologram recording material of the present invention comprises a photoconductive element, a secondary hyperpolarization element, and an electron or hole trapping element. wherein, and a hologram recording material comprising a polymer composition of the structure having no inversion symmetry center, before
The polymer composition is selected from the following (I) to (V):
At least one. (I) 2- (N-carbazolyl) ethyl acrylate
And 2- [4- (β, β-dicyanovinyl) phenoxy]
Ethyl methacrylate copolymer, dibutyl phthalate
(II) 3- (N-ethylcarbazolylmethyl) acrylic polymer composition containing trinitrofluorenone
Rate and 2- {N- [4- (β-cyano-β-ethoxy)
Carbonylvinyl)]-N-methylanilinodiethyl
Methacrylate copolymer, dibutyl phthalate, tributyl
Nitrofluorenone-containing polymer composition (III) 2- (N-carbazolyl) ethyl acryle
And 2- {N- [4- (β-cyano-β-ethoxy)
Rubonyl vinyl)]-N-methylanilinodiethyl
Tacrylate copolymer, containing trinitrofluorenone
Polymer composition (IV) having 2- [4- (β, β-dicyanovinyl) pheno
[Xy] ethyl methacrylate and methyl methacrylate
Copolymer, polycarbonate, vinyl carbazole
Oligomer, N, N'-diphenyl-N ', N'-bis
(3-toluyl) -4,4'-diaminobiphenyl
Polymer composition having (V) polyvinyl carbazole, N, N-diethyl-4
- nitro aniline, jib Chirufutareto, tetranitro
Polymer composition containing fluorenone

Another hologram recording material of the present invention is:
An element having photoconductivity, an element exhibiting secondary hyperpolarization, and
And an electron or hole trapping element, and
Both sides of recording layer made of polymer composition with no structure
A hologram recording element provided with a transparent electrode layer on the side
The polymer composition is selected from the following (I) to (V):
At least one selected from the list. (I) 2- (N-carbazolyl) ethyl acrylate
And 2- [4- (β, β-dicyanovinyl) phenoxy]
Ethyl methacrylate copolymer, dibutyl phthalate
(II) 3- (N-ethylcarbazolylmethyl) acrylic polymer composition containing trinitrofluorenone
Rate and 2- {N- [4- (β-cyano-β-ethoxy)
Carbonylvinyl)]-N-methylanilinodiethyl
Methacrylate copolymer, dibutyl phthalate, tributyl
Nitrofluorenone-containing polymer composition (III) 2- (N-carbazolyl) ethyl acryle
And 2- {N- [4- (β-cyano-β-ethoxy)
Rubonyl vinyl)]-N-methylanilinodiethyl
Tacrylate copolymer, containing trinitrofluorenone
Polymer composition (IV) having 2- [4- (β, β-dicyanovinyl) pheno
[Xy] ethyl methacrylate and methyl methacrylate
Copolymer, polycarbonate, vinyl carbazole
Oligomer, N, N'-diphenyl-N ', N'-bis
(3-toluyl) -4,4'-diaminobiphenyl
Polymer composition having (V) polyvinyl carbazole, N, N-diethyl-4
-Nitroaniline, dibutyl phthalate, tetranitro
Polymer composition containing fluorenone

Next, a method of manufacturing a hologram recording element of the present invention is characterized by including at least one of the following steps (i) to (iv). (I) an element having photoconductivity, an element exhibiting secondary hyperpolarization, and a solution preparation step of preparing a solution of a polymer composition including an electron or hole trapping element; A film forming step of applying and drying a solution to form a film of the polymer composition; (iii) preparing a plurality of films prepared in the film forming step and a transparent substrate having a transparent electrode layer formed on one surface side; A step of preparing a plurality of sheets, melting and press-molding them in a state where they are overlapped so as to sandwich a plurality of films on a transparent substrate so that the film and the transparent electrode layer are in contact with each other, and (iv) glass of the polymer composition An electric field is applied between the transparent electrode layers while heating the recording layer to a temperature close to or higher than the transition temperature, and then cooled and polarized.

[0013] The hologram recording method of the present invention, a request
Item for recording the hologram recording material according to item 1 or 2
A law element having a photoconductive, and includes a secondary element indicating hyperpolarization, and transparent provided on both sides of the recording layer comprising a polymer composition has a structure having no inversion symmetry center In this method, a hologram is recorded by irradiating coherent light from both sides of the recording layer with a DC voltage applied between the electrode layers.

In the above structure, it is preferable to provide an insulating layer between the recording layer and the transparent electrode layer. Further, in the above configuration, it is preferable that the recording layer is made of a polymer composition containing a monomer having a carbazole skeleton.

[0015]

The hologram recording material of the present invention comprises at least three components: a low-molecular, monomer or polymer having photoconductivity, a low-molecular, monomer or polymer exhibiting secondary hyperpolarization, and an electron or hole trapping substance. including. By making the polymer composition containing these into a structure having no reversal center, of the three elements, the element exhibiting secondary hyperpolarization contributes,
The Pockels effect appears. In order to form a structure having no inversion symmetry center, these three elements are synthesized or dispersed and formed into a thin film or plate, and then heated to a temperature close to or higher than the glass transition temperature of the polymer composition containing these three elements. This can be achieved by performing a poling process (polarizing process) while applying an electric field while applying the electric field. An element having a large dipole moment in the ground state and a second-order hyperpolarization having a large second-order hyperpolarizability β induces a larger Pockels effect, so that hologram recording sensitivity and diffraction efficiency can be improved. it can. In addition, among the three elements, since it contains an electron or hole trapping substance, carriers generated in the element having photoconductivity by light irradiation are easily trapped, and a space charge distribution is generated inside the polymer composition, Since the internal electric field due to the charge distribution is increased, hologram recording sensitivity and diffraction efficiency are improved.

In a hologram recording element having a transparent electrode layer on both sides of a recording layer made of a polymer composition as described above, an electric field can be applied in the thickness direction of the recording layer. The structure becomes a structure spontaneously polarized in a direction perpendicular to the recording medium. Therefore, recording of an optical phase grating parallel to the recording surface, that is, recording of a reflection hologram becomes possible. Further, it is possible to perform recording while applying an electric field during recording. Further, even when the orientation generated by the polarization treatment is relaxed and the performance is lowered, it is easy to perform the polarization treatment again.

Further, by forming a basic configuration of a hologram recording element, in which transparent electrode layers are provided on both sides of a recording layer made of a polymer composition, on a support such as a transparent substrate, the entire hologram recording element is formed. Can be improved in mechanical strength.

Further, by providing an insulating layer between the recording layer made of the polymer composition and the transparent electrode layer, it is possible to improve the dielectric strength and to increase the electric field applied in the recording layer. Can be.

The method for producing a hologram recording element of the present invention is characterized in that a film of a polymer composition containing an element having photoconductivity in a solid state and an element exhibiting secondary hyperpolarization is applied and dried to form a film. A plurality of the films are molded and melt-pressed in a state where the films are stacked so as to be sandwiched between two transparent substrates having a transparent electrode layer formed on one side so that the transparent electrode layers are in contact with each other. An element is produced by applying an electric field between the transparent electrode layers while heating the recording layer to a temperature close to or higher than the glass transition temperature of the molecular composition, and then cooling the recording layer. . (1) Deformation of the transparent electrode layer due to electrostatic attraction does not occur in the poling process at the time of heating because the transparent electrode layer is supported by the transparent substrate. (2) Since a film of the polymer composition is formed from a solution state and then fused by pressure molding, a relatively low temperature,
The molding of the recording layer can be completed by heating for a short period of time, and the performance of the recording layer is less thermally deteriorated. (3) Since a plurality of films are laminated and melt-pressed to form a recording layer, the thickness of the recording layer can be easily increased, and an element having high diffraction efficiency can be manufactured.

Also, the hologram recording method of the present invention includes an element having photoconductivity, an element exhibiting secondary hyperpolarization,
And between the transparent electrode layers provided on both sides of the recording layer comprising a polymer composition having a structure having no inversion symmetry center,
Since coherent light is irradiated from both sides of the recording layer in a state where a DC voltage is applied, radical ion dissociation efficiency by light irradiation can be increased, and the space charge distribution generated by this can be increased in the thickness direction of the recording layer. Since it can be formed and the electro-optic constant of the recording layer can be effectively used, hologram recording sensitivity and diffraction efficiency can be improved.

[0021]

EXAMPLES Examples of the hologram recording material, the hologram recording element and the method of manufacturing the same according to the present invention will be described below.

First, the hologram recording material of the present invention will be described. The polymer composition including the element having photoconductivity, the element exhibiting secondary hyperpolarization, and the electron or hole trapping element may be a polymer having photoconductivity or (reactive).
Monomer (hereinafter, “(reactive) monomer” referred to in the present specification is a general term for a low-molecular compound or a non-reactive low-molecular compound that reacts to form a polymer. A polymer or (reactive) monomer exhibiting secondary hyperpolarization and an electron or hole trapping substance, by blending, molecular dispersion or copolymerization. It is obtained by doing. By subjecting the polymer composition thus obtained to a poling treatment in which an electric field is applied while being heated to a temperature close to or higher than the glass transition temperature, a structure having no inversion symmetry center can be obtained.

Photoconductive polymer or (reactive)
As the monomer, a monomer or polymer having a carbazole skeleton such as vinyl carbazole or carbazolyl alkyl methacrylate, N, N′-diphenyl-N,
There are triphenylamine derivatives such as N'-bis (3-toluyl) -4,4'-diaminobiphenyl (TPD), pyrazoline derivatives, triphenylmethane derivatives, hydrazone derivatives, oxadiazole derivatives, indoline derivatives and the like. Preferably can also serve as a hole trapping substance,
It is a polymer having a carbazole skeleton that does not cause aggregation.

Since the secondary hyperpolarization is a property of most or more organic molecules, the polymer or (reactive) monomer exhibiting the secondary hyperpolarization is not particularly limited. (Ie, to obtain a large Pockels effect), the dipole moment in the ground state is large and the second-order hyperpolarization β is large (reactivity)
Monomers or polymers are preferred. Examples of such compounds include nitroaniline derivatives, benzylidene malononitrile derivatives, β-phenyl-α-cyanoacrylic acid derivatives, β-aminostyrene derivatives, tricyanostyrene derivatives, aminonitroazobenzene derivatives And intramolecular charge transfer dyes such as aminonitrostilbene derivatives. When these derivatives have a reactive functional group such as a vinyl group, an acryloyl group, and a methacryloyl group, they can be used as a reactive monomer, and if polymerized, they can be used as a polymer.

As the electron or hole trapping substance, a strong electron-accepting compound such as an aromatic compound having a plurality of nitro groups and cyano groups, or an aromatic compound having an amino group, an alkyl or arylamino group, or the like. Strong electron donating compounds can be mentioned. It may have a reactive functional group such as a vinyl group, an acryloyl group, and a methacryloyl group. In addition, dimer anion radicals and 2
Compounds capable of forming a dimer ion radical such as a dimer cation radical are preferable because they are energetically stable, form deeper traps, easily accumulate charges, and can improve hologram recording sensitivity and diffraction efficiency. .
Among them, a compound capable of forming a carbazole dimer cation radical is preferable since it has relatively high solubility. The compound capable of forming a carbazole dimer cation radical is specifically a carbazole derivative, and these oligomers and polymers have a strong trap because the carbazole skeleton forming the dimer portion is adjacent to the carbazole skeleton. Becomes When the photoconductive (reactive) monomer or polymer is a (reactive) monomer or polymer having a carbazole skeleton such as polyvinyl carbazole or carbazolyl alkyl acrylate, these also serve as a hole-trapping substance. May be.

Next, a polymer or a (reactive) monomer having photoconductivity, a polymer or a (reactive) monomer capable of exhibiting a large Pockels effect by the poling treatment,
Blend, molecular dispersion or copolymerization with an electron or hole trapping substance will be described. (1) When the three are reactive monomers, a polymer composition having all properties can be obtained by copolymerization. Copolymerization can be easily carried out by conventional radical polymerization. Ionic polymerization is also possible depending on the combination of monomers. (2) When the three are polymers, a polymer composition having all properties can be obtained by blending in a solution or a molten state. (3) When one component is a monomer and the other component is a polymer, a polymer composition having all properties can be obtained by molecularly dispersing the monomer in the polymer. (4) In the case of a monomer that is not reactive in all three, a polymer composition having all properties can be obtained by molecularly dispersing the three in a polymer as a binder. In addition,
As a binder used in this case, a material compatible with the three may be appropriately selected.

On the other hand, a monomer or a polymer exhibiting a large secondary hyperpolarization (reactive) tends to agglomerate, and if the compatibility between the polymers is low, transparency is obtained by light scattering. May not be possible,
The most preferred method is to copolymerize the reactive monomers of the above (1) to obtain a polymer composition.

In order to increase the photoconductive sensitivity wavelength or to increase the quantum yield, an electron-donating substance or an electron-accepting substance is added, and the polymer or the photoconductive polymer is added. Forming a charge transfer complex with a monomer is also a preferred configuration. For example, in the case where polyvinyl carbazole is used as the photoconductive polymer composition, sensitivity is also produced for red light by adding trinitrofluorenone, tetranitrofluorenone, or the like. In addition, when these additive substances have a reactive functional group, it is also preferable to copolymerize as a comonomer.

As for the (reactive) monomer or polymer exhibiting secondary hyperpolarization, those having a small absorption at the wavelength for recording and reproducing the hologram are preferable. Not.

In general, the one having a large secondary hyperpolarization β shifts the absorption wavelength longer, but alkoxybenzylidene malononitrile, β- (4-alkoxyphenyl) -α-cyanoacrylic acid derivative, etc. are almost completely in the visible region. Despite having no absorption, it has β similar to nitroanilines that have absorption up to about 500 nm. Therefore, using a monomer or polymer having these in a side chain, for example, using an argon laser of 488 nm as a recording light source Even become possible.

FIG. 1 is a perspective view of an embodiment of the hologram recording element of the present invention, and FIG. 2 is a sectional view taken along line AA 'of FIG. This recording element includes an element having photoconductivity, an element exhibiting secondary hyperpolarization, and a transparent electrode 2 on both sides of a recording layer 1 made of a polymer composition having a structure having no inversion symmetry center. The 2 ′ transparent electrode side is configured. The form of the hologram recording element of the present invention may be, for example, a form as shown in FIGS. That is, as shown in FIG. 3, the insulating layers 4, 4 'are provided between the recording layer 1 and the transparent electrodes 2, 2'.
May be provided. Further, as shown in FIG. 4, insulating protective layers 3, 3 'for protecting the transparent electrodes may be provided on the surfaces of the transparent electrodes 2, 2'. Further, as shown in FIG. 5, a first transparent electrode 2 'is provided on a transparent substrate 5, a recording layer 1 made of the hologram recording material of the present invention is provided on the first transparent electrode 2', and A second transparent electrode 2 may be provided. Also, as shown in FIG. 6, the first transparent substrate 5 '
A transparent electrode 2 'is provided, and a recording layer 1 made of the hologram recording material of the present invention is provided on the first transparent electrode 2'.
May be provided on the second transparent electrode 2, and the second transparent substrate 5 may be provided on the second transparent electrode 2.

In order to achieve the above configuration, it is necessary to process the polymer composition to be the recording layer 1 into a substrate or a thin film. For this purpose, there are roughly two methods. The first method is a method of melting and molding, and can be processed into various shapes of substrates or thin films using a kneading extruder, a hot press, an injection molding machine or a stretching machine. In injection molding and stretching, a large anisotropy and a density difference (refractive index difference) depending on the position are likely to appear. Therefore, it is important to select conditions and perform annealing after molding.

The second method is a method of molding in a solution state, and can be formed into a thin film by a dipping method, a casting method, a spin coating method or the like. These methods are
Generally, it tends to be difficult to form a thick one,
Among them, a casting method in which a high-concentration solution is formed using a doctor blade and a casting method in which the high-concentration solution is dried from both sides while falling through a slit are preferable.

It is also useful to combine the first method and the second method in which the layers formed by the casting method are laminated and then melt-molded. That is, the solution of the hologram recording material of the present invention is applied to the transparent electrodes 2 and 2 ′ and dried to form the recording layer 1, and the recording layers 1 are superposed and melted and pressed to be welded. According to the hologram recording element manufacturing method of the present invention for performing the processing,
Compared with the method of molding only by melt molding accompanied by the kneading and extrusion operation, the heat history applied to the recording layer 1 (that is, the hologram recording material of the present invention) is small and the deterioration of the performance is small, which is preferable. Further, in order to increase the thickness of the recording layer 1, a plurality of polymer composition films formed by a casting method or the like are transferred to a transparent substrate provided with a transparent electrode layer (for example, the transparent electrodes 2 and 2 shown in FIG. 5). The method of the present invention is preferable because the same operation and effect can be obtained by a method of melting and pressing the transparent electrodes 2 and 2 ′ between the '′ and the transparent substrates 5 and 5 ′).

The transparent electrodes formed on both sides of the recording layer 1
It is sufficient that the transparent electrode is transparent to the wavelength of light used for hologram recording and reproduction. For example, a normal transparent electrode such as ITO or SnO ₂ can be used. Or, for example, 1
Very thin, for example, aluminum,
Metals such as gold and silver can be used as the translucent electrode. However, a semi-transparent electrode that is not sufficiently transparent is not preferable because the amount of light used for recording or reproduction is reduced. Note that the thickness of the transparent electrode is preferably excluded from interference conditions determined by the wavelength and incident angle of light used for recording or reproduction.

In the recording element shown in FIG. 3, insulating layers 4 and 4 'are provided on both sides of a recording layer 1 made of a polymer composition having photoconductivity and producing the Pockels effect, and a transparent electrode layer is provided thereon. 2, 2 'are provided. By providing such insulating layers 4 and 4 ', the withstand voltage is improved, and the electric field applied in the recording layer can be increased. Note that the insulating layer may be provided only on one surface.

The transparent substrates with transparent electrodes 2, 2 'shown in FIG.
An insulating protective layer provided on a transparent substrate to protect the
3 'may be a transparent material at the recording / reproducing wavelength, and an organic or inorganic material is provided.

The transparent substrates 5, 5 'shown in FIG.
Any material may be used as long as it has good light transmittance with respect to the wavelength of light used for hologram recording or reproduction, and a quartz plate or various glass substrates exclusively used as a transparent substrate material can be used. The thickness of the transparent substrates 5 and 5 ′ is preferably about 50 μm or more in order to prevent the occurrence of optical interference in the substrates.
In order to effectively use the amount of light that can be used for hologram recording or reproduction, it is also preferable to apply an anti-reflection coating for preventing surface reflection on the transparent substrate 5, 5 'on the side where the transparent electrodes 2, 2' are not provided. .

The recording layer 1 may be in the form of a plate or a thin film, and the transparent electrodes 2 and 2 ′ provided on the recording layer 1 may be manufactured by a vacuum film forming method such as vacuum evaporation or sputtering. Good. As shown in FIG. 5 or FIG. 6, as a method for forming the transparent electrode 2 or 2 ′ on the transparent substrate 5, in addition to a vacuum film forming method such as vacuum evaporation or sputtering, for example, a spray pyrolysis method It can also be formed by a wet film forming method such as

Next, a description will be given of a poling process for imparting a property that generates the Pockels effect to the polymer composition constituting the recording layer 1. The polymer composition having the transparent electrode layers 2 and 2 'formed on both sides as described above is subjected to a poling treatment for applying an electric field while being heated to a temperature close to or higher than the glass transition temperature, thereby obtaining a monomer or polymer. The dipoles as part of are oriented and polarized. When cooled below the glass transition temperature while maintaining the polarized state, the molecular orientation is fixed and a structure having no inversion symmetry center is obtained. A substance having such a structure has a Pockels effect.

The electric field is applied by applying a voltage between the transparent electrode layers formed on both sides. If the application of an electric field is stopped while heating, the molecular orientation is relaxed and the Pockels effect is reduced. It is preferable to carry out.

Since the polymer composition to be subjected to the poling treatment (that is, the recording layer 1) has photoconductivity, the poling treatment can be performed in an environment where light having a wavelength having photoconductivity sensitivity is not irradiated. preferable.

The application of the electric field does not necessarily have to be a method of applying a voltage between the transparent electrodes formed on both sides. That is, an electric field may be applied to the plate-like or thin-film recording material before the transparent electrodes are formed on both sides of the recording layer 1 by corona charging using a corotron or the like. In the poling performed by such a means, a poling process can be performed before forming an electrode or the like into an element shape, and thus is a particularly useful method when a large number of sheet-like hologram recording materials are formed.

Further, for example, in the case of a hologram recording element having a configuration as shown in FIG. 6, if the method of manufacturing a hologram recording element of the present invention is used, as described above, the hologram recording element is caused by the electrostatic attraction in the polling process during heating. Transparent electrode 2,
The deformation of 2 ′ is preferable because the transparent electrodes 2 and 2 ′ are supported by the transparent substrates 5 and 5 ′, and a good hologram recording element can be formed.

Next, a hologram recording method using the hologram recording element of the present invention will be described. The polymer composition constituting the recording layer 1 of the hologram recording element of the present invention as described above is a so-called poled polymer, and each dipole in the polymer composition is perpendicular to the surface of the recording layer 1. In this structure, the elements are oriented. Therefore, when there is an electric field in a direction perpendicular to the surface of the recording layer 1, the refractive index in a direction perpendicular or parallel to the surface of the recording layer 1 changes.

[0046] In general, the electro-optic constant of Porudoporima, most large r _33, as shown in the following Formula.

[0047]

(Equation 1)

[0048] Thus, the greatest r ₃₃ light irradiation system using the hologram recording light irradiation system, such as vertical interference fringes are formed in the poling direction as illustrated in FIG. 7 can be considered. In this case, since the interference fringes themselves are perpendicular to the hologram recording surface, a transmission hologram recording method is used. However, if the recording area is increased, the distance between the electrodes becomes longer. Therefore, if the electric field required for the poling process is the same, it is necessary to apply a large voltage in proportion to the distance between the electrodes, which is practically impossible.

Therefore, as shown in FIG. 8, by providing the transparent electrode layers 2 and 2 'on both sides of the recording layer 1, polling can be performed in the direction 6 perpendicular to the hologram recording surface, and Object light 7 and reference light 7 'from both sides
Irradiating is preferable.
In this case, in the recording layer 1, interference fringes nearly parallel to the surface of the recording layer 1 are formed. Carriers are generated at the bright portion of the interference fringes and diffuse or move. The carrier distribution remains in the same pitch even if there is a phase shift with respect to the light interference fringes, and as a result, a charge distribution is formed in the polymer composition (that is, the recording layer 1). Therefore, the internal electric field due to the residual charges is substantially the same as the interference fringe pitch at the time of exposure. The Pockels effect occurs in the recording layer 1 according to the distribution of the internal electric field, and a refractive index distribution substantially equal to the interference fringe pitch at the time of exposure occurs. As a result, hologram recording is performed.
Reference numeral 9 denotes a power supply for applying an electric field, and 10
Is a switch.

The recording layer made of the above polymer composition has
Since an electric field is applied at the time of exposure, radical ion pairs are efficiently generated in the bright portions of the interference fringes, so that a large electric field due to space charge distribution is formed.

The light used for recording has a wavelength within the photoconductive sensitivity range of the polymer composition having photoconductive properties and uses coherent (coherent) light. In particular, it is preferable to use laser light from which coherent light can be easily obtained.
When performing hologram recording, the coherent light of the same light source is split into two light beams by a beam splitter or the like, and then the light is irradiated so that the optical path lengths to the hologram recording element are almost the same. Is preferred.

As will be described later, the larger the angle of incidence of the reference beam on the recording layer during reproduction, the larger the change in the refractive index n _z
It is effective because it is affected by FIG. 9 shows an example of an interferometer to which the hologram recording method of the present invention can be applied, using an overall schematic diagram.

A light beam emitted from a laser light source 21 enters a shutter 23 via a mirror 22 and is then split into two light beams by a beam splitter 24. One light beam is diverged by a lens 25 to irradiate the subject 20. ,
The other light beam is diverged by the lens 27 via the mirror 26 and irradiates the recording layer 1. The light applied to the subject 20 is modulated by information of the subject, and a part of the light irradiates the recording layer 1. In the recording layer 1, two lights interfere with each other to form a carrier distribution according to the interference fringes. The timer device 28 controls the exposure time and the electric field applied to the recording layer.

Next, a hologram reproducing method using the hologram recording element of the present invention will be described. As shown in FIG. 10, by irradiating one light beam used at the time of exposure as reference light 11, reproduction light 12 is generated by diffraction, and hologram reproduction is performed.

The reference light 11 has a different refractive index depending on its incident angle and polarization. That is, the influence of parallel component n _x in the plane of the components n _z in the direction perpendicular to the surface of the recording layer the recording layer in the case of s-polarized light, parallel to the plane of the recording layer in the case of the p-polarized light receiving a direction of the influence of the components n _x and n _y. Electrooptical constant r ₃₃ is the refractive index change greater since n _z than r ₁₃ or r ₂₃ is n _y, is greater than the change in n _x s
The use of polarized light is advantageous.

However, in the hologram recording method of the present invention, since a reflection type hologram having wavelength selectivity is formed, it is not necessary to use coherent light or polarized light such as laser light at the time of reproduction. Of non-monochromatic light sources can be used. In the case of a non-monochromatic light source, the photoconductive sensitivity of the recording layer increases as the wavelength becomes shorter. Therefore, it is preferable that the short-wavelength component of the reference light be small in order not to generate new carriers. Further, in order to suppress the image distortion of the hologram, when the reference light at the time of recording is divergent light, the reference light at the time of reproduction also uses divergent light, and when the reference light at the time of recording is parallel light, It is preferable to use parallel light as reference light at the time of reproduction.

Further, when irradiating the reference light at the time of reproduction,
When a large electric field is applied, generation of carriers during light irradiation is promoted to erase the recorded carrier distribution. Therefore, it is preferable to apply an electric field as in recording.

Next, a hologram erasing method using the hologram recording element of the present invention will be described. To erase the recorded hologram, the recording layer is irradiated with light of a wavelength component having photoconductivity sensitivity of the recording layer in a strong light amount to generate a new carrier. The distribution disappears. It is also preferable to apply an electric field to the recording layer together with the irradiation of the erasing light. In order to uniformly erase the recording layer, it is preferable to irradiate the hologram recording element with a uniform light amount. The erasing light does not have to be coherent light.

Next, specific examples of the hologram recording material, the hologram recording element, the method of manufacturing the same, and the hologram recording method of the present invention will be described in detail. Example 1 <Production of Raw Material for Hologram Recording Material> In a three-necked flask equipped with a nitrogen inlet tube, a reflux condenser, and a stirrer, 10 parts by weight of N-carbazolylethyl acrylate and p- (β-dicyanovinylphenoxy) ethyl methacrylate were added. 10 parts by weight and 0.2 parts by weight of azobisisobutyronitrile were added, dissolved in 80 parts by weight of tetrahydrofuran, and polymerized at 80 ° C. for 5 hours while introducing nitrogen while stirring.

Next, after allowing to cool, it was poured into 1000 parts of methanol to cause reprecipitation. After filtration by suction filtration, the polymer was dried under vacuum to obtain a polymer. <Manufacture of hologram recording element> 10 parts by weight of dibutyl phthalate and 1 part by weight of trinitrofluorenone were mixed with 100 parts by weight of this polymer to obtain 2 parts.
After repeated kneading, the extruder was extruded by changing the nozzle of the extruder to a rectangular one to obtain a plate-like sample having a width of 4 cm and a thickness of 5 mm.
Next, after processing into a shape of 3 cm × 3 cm, it was dipped in an aqueous acrylic resin and dried to form an insulating layer. Subsequently, a 2.5 cm × 2.5 cm mask is applied, and the ITO
The film was formed on each side by sputtering, and a transparent electrode layer was formed on both sides.

Next, the polling process will be described.
In a dark room, the sample was placed in a thermostat and heated to 120 ° C., and then 10 kV was applied between both electrodes. After a lapse of 10 minutes, the heater of the thermostat was turned off, and the mixture was allowed to cool while an electric field was applied. After 3 hours, the temperature dropped to room temperature. The applied electric field was removed, and a sample was taken out. Through the above steps, the hologram recording device of the present invention was obtained.

<Hologram Recording Method, Reproduction Method, and Erasing Method> In a dark room, an interferometer using an argon laser as a light source is assembled, and the above-mentioned hologram recording element has an incident angle of 30 ° from one surface with respect to the surface. It was set so that it could be incident at 5 degrees from the other surface.

Next, irradiation with a light amount of about 500 μW / cm ² was started from both sides with 1 kV applied between the transparent electrode layers. After 10 seconds, the applied electric field was removed and the light irradiation was stopped.

Subsequently, when only reproduction light having an incident angle of 30 degrees was irradiated from one surface, reflected diffracted light having an emission angle of about -5 degrees was observed, and a hologram was reproduced. Next, in order to erase the hologram, the erasing light from the xenon lamp was used for 3 hours.
Irradiated for 0 seconds. An attempt was made to reproduce a hologram using the above-described reproduction optical system, but no reflected diffracted light was observed.

Example 2 <Production of Raw Materials for Hologram Recording Material> In a three-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer, 10 parts by weight of 3- (N-ethylcarbazolyl) methyl acrylate, 2- ｛ 10 parts by weight of N- [4- (β-cyano-ethoxycarbonylvinyl)]-N-methylanilinodiethyl methacrylate and 0.2 part by weight of azobisisobutyronitrile are added, and tetrahydrofuran 80 is added.
Dissolved in parts by weight and stirred at 80 ° C for 5
Polymerized for hours.

Next, after allowing to cool, it was poured into 1000 parts of methanol to cause reprecipitation. After filtration by suction filtration, the polymer was dried under vacuum to obtain a polymer. <Production of hologram recording element> In 100 parts by weight of this polymer, 5 parts by weight of dibutyl phthalate and 10 parts by weight of trinitrofluorenone were dissolved in 200 parts by weight of tetrahydrofuran.

On the other hand, a slide glass on which an ITO layer was formed was prepared, and a surface having the ITO layer was spin-coated with a polyvinyl alcohol solution and dried to form an insulating layer. On this, the above-mentioned polymer solution was applied using a doctor knife and dried to form a polymer composition thin film of about 100 μm. Further, an insulating layer was formed by spin coating a polyvinyl alcohol solution.

Subsequently, an ITO film was formed by sputtering using a mask of 2.5 cm × 2.5 cm to form a transparent electrode layer. Next, the polling process will be described.

In a dark room, the sample was placed on a heating plate for 1 hour.
After heating to 30 ° C., 500 V was applied between both electrodes. After a lapse of 30 minutes, the heater plate was de-energized and allowed to cool while applying an electric field. After 2 hours, the temperature dropped to room temperature. The applied electric field was removed, and a sample was taken out.
Through the above steps, the hologram recording device of the present invention was obtained.

<Hologram Recording Method, Reproduction Method, and Erasing Method> In a dark room, an interferometer using a helium neon laser as a light source is assembled, and an incident angle of 30 from one surface with respect to the surface of the hologram recording element described above. It was set so that it could be incident at 5 degrees from the other surface.

Next, irradiation with a light amount of about 300 μW / cm ² was started from both sides with 200 V applied between the transparent electrode layers. After a lapse of 40 seconds, the applied electric field was removed and the light irradiation was stopped.

Subsequently, when only reproducing light having an incident angle of 30 degrees was irradiated from one surface, reflected diffracted light having an outgoing angle of about -5 degrees was observed, and a hologram was reproduced. Next, in order to erase the hologram, the erasing light from the xenon lamp was used for 3 hours.
Irradiated for 0 seconds. An attempt was made to reproduce a hologram using the above-described reproduction optical system, but no reflected diffracted light was observed.

Example 3 <Production of Raw Materials for Hologram Recording Material> In a three-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer, 10 parts by weight of 2- (N-carbazolyl) ethyl methacrylate and 5 parts by weight of methyl acrylate , 2- ｛N
-[4- (β-cyano-ethoxycarbonylvinyl)]
10 parts by weight of -N-methylanilinodiethyl methacrylate and 0.2 parts by weight of azobisisobutyronitrile were added, dissolved in 80 parts by weight of tetrahydrofuran, and polymerized at 80 ° C for 5 hours while introducing nitrogen while stirring.

Next, after allowing to cool, it was poured into 1000 parts of methanol to cause reprecipitation. After filtration by suction filtration, the polymer was dried under vacuum to obtain a polymer. <Production of hologram recording element> 5 parts by weight of tetranitrofluorenone was mixed with 100 parts by weight of this polymer, and kneaded in the same manner as in Example 1 to obtain a hologram recording element of the present invention. Further, recording, reproduction and erasing of the hologram could be performed in the same manner as in Example 2.

Example 4 <Preparation of hologram recording material and hologram recording element> 2- [4- (β, β-dicyanovinyl) phenoxy] ethyl methacrylate was placed in a three-necked flask equipped with a nitrogen inlet tube, a reflux condenser, and a stirrer. 20 parts by weight, methyl methacrylate 10 parts by weight, azobisisobutyronitrile 0.
2 parts by weight were added, dissolved in 70 parts by weight of tetrahydrofuran, and polymerized at 80 ° C. for 5 hours while introducing nitrogen under stirring.

After allowing to cool, it was poured into 1000 parts of methanol to cause reprecipitation. After filtration by suction filtration, vacuum drying was performed to obtain a white polymer powder. In a three-necked flask equipped with a nitrogen inlet tube, a reflux condenser, and a stirrer, 20 parts by weight of vinylcarbazole, 5 parts by weight of azobisisobutyronitrile, and 15 parts by weight of carbon tetrachloride as a chain transfer agent were put into 60 parts by weight of tetrahydrofuran. And polymerized at 80 ° C. for 3 hours while introducing nitrogen under stirring. After allowing to cool, it was poured into 1000 parts of methanol to cause reprecipitation. After filtration by suction filtration, the residue was dried under vacuum to obtain a white vinylcarbazole oligomer.

Subsequently, 60 parts by weight of the aforementioned polymer, 10 parts by weight of polycarbonate, and vinyl carbazole oligomer 1
0 parts by weight and 20 parts by weight of TPD
Dissolved in 0 parts by weight. A glass slide made of ITO on one side is placed with the side with ITO facing up, and the above-mentioned solution is applied thereon using a doctor blade and dried.
A hologram recording material thin film of about 100 μm was formed.
By repeating the same operation, two hologram recording materials and I
A slide glass on which TO was laminated was obtained. After sufficiently performing vacuum heating and drying, the hologram recording materials of both samples were overlapped so as to be in close contact with each other, and bonded using a heating press device. At this time, 200 μm so that the recording layer does not become thin.
m was sandwiched between slide glasses as a spacer.

This sample was heated to 85 ° C. on a hot plate in a dark room, and then 10 kV was applied between both electrodes.
After a lapse of 10 minutes, the heater of the hot plate was turned off, and the plate was allowed to cool while an electric field was applied. One hour later, the temperature dropped to room temperature, so the applied electric field was removed, and a sample was taken out. The sample formed by the above steps was used as a hologram recording element.

<Hologram Recording, Reproduction and Erasure> An interferometer using a helium-cadmium laser as a light source is assembled in a dark room so that the hologram recording element can be incident at an incident angle of 30 degrees from one side and 5 degrees from the other side. installed.

While applying 2 kV between the transparent electrodes, irradiation with a light amount of about 300 μW / cm 2 was started from both sides. After a lapse of 40 seconds, the applied electric field was removed and the light irradiation was stopped.

Subsequently, when only light having an incident angle of 30 degrees was irradiated, reflected diffracted light having an outgoing angle of about -5 degrees was observed. Reproduction was attempted in the same manner after irradiation with a xenon lamp for 30 seconds, but no diffracted light was observed.

Example 5 <Preparation of Hologram Recording Material and Recording Element> Polyvinylcarbazole 5 parts by weight, N, N-diethyl-
1.2 parts by weight of 4-nitroaniline, 0.07 parts by weight of tetranitrofluorenone, and 0.65 parts by weight of dibutyl phthalate were dissolved in 20 parts by weight of tetrahydrofuran. Using a doctor blade, the above solution was applied on a glass plate whose surface was subjected to a hydrophobic treatment with a dichloromethane solution of chlorotrimethylsilane, and dried to obtain a thin film of about 50 μm. This was cut into a size of 2 cm x 2 cm and 7
Stacked. This laminated film was sandwiched between two slide glasses each having a part of one surface made of ITO and a spacer made of polyethylene naphthalate having a thickness of 300 μm, and bonded using a heating press.

The sample was heated to 75 ° C. on a hot plate in a dark room, and then 15 kV was applied between both electrodes.
After a lapse of 10 minutes, the heater of the hot plate was turned off, and the plate was allowed to cool while an electric field was applied. One hour later, the temperature dropped to room temperature, so the applied electric field was removed, and a sample was taken out. The sample formed by the above steps was used as a hologram recording element.

<Hologram Recording, Reproduction and Erasure> An interferometer using a 632.8 nm helium-neon laser as a light source was assembled in a dark room, and the hologram recording element was incident at an angle of 30 degrees from one side and 5 degrees from the other side. It was installed so that it could be incident.

While applying 15 kV between the transparent electrodes, irradiation with a light amount of about 500 μW / cm 2 was started from both sides. After a lapse of 20 seconds, the applied electric field was removed and the light irradiation was stopped.

Subsequently, when only light having an incident angle of 30 degrees was irradiated, reflected diffracted light having an outgoing angle of about -5 degrees was observed. While applying 15 kV between the electrodes, the xenon lamp was
After irradiation for 0 seconds, reproduction was attempted in the same manner, but no diffracted light was observed.

[0087]

As described in detail above, the hologram recording material of the present invention includes a photoconductive element, an element exhibiting secondary hyperpolarization and an electron or hole trapping element, and has a center of inversion symmetry. The hologram recording element of the present invention is a polymer having a structure that does not have an element having photoconductivity, an element having secondary hyperpolarization, and does not have a center of inversion symmetry. Since the composition is used as a recording layer and a transparent electrode is provided on both sides of the recording layer, the hologram can be recorded, reproduced and erased any number of times. There is an effect that a hologram recording element suitable for an element or the like can be provided.

In particular, the hologram recording material and the recording layer of the recording element have a structure that includes an element having photoconductivity, an element exhibiting secondary hyperpolarization and an electron or hole trapping element, and has no center of inversion symmetry. When a polymer composition is used, more carriers generated by light irradiation are more likely to remain and a larger Pockels effect is exhibited, so that hologram recording sensitivity or diffraction efficiency is improved.

Further, since the recording layer is formed of an organic material such as a polymer composition, the area of the hologram recording element can be increased. In addition, according to the method for manufacturing a hologram recording element of the present invention, the hologram recording element can be easily obtained, so that the cost can be reduced. In addition, it is easy to increase the area of the recording element.

In the hologram recording method of the present invention, since an electric field is applied to the recording layer at the same time as light irradiation, carrier generation is promoted, and the formed space charge distribution is effectively coupled to the change in the refractive index. Therefore, there is an effect that the hologram recording sensitivity is further improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of one embodiment of a hologram recording element of the present invention.

FIG. 2 is a schematic cross-sectional view taken along line AA ′ of one embodiment of the hologram recording element of the present invention shown in FIG.

FIG. 3 is a schematic sectional view of another embodiment of the hologram recording element of the present invention.

FIG. 4 is a schematic sectional view of another embodiment of the hologram recording element of the present invention.

FIG. 5 is a schematic sectional view of another embodiment of the hologram recording element of the present invention.

FIG. 6 is a schematic sectional view of another embodiment of the hologram recording element of the present invention.

FIG. 7 is a schematic diagram of a hologram recording method that can effectively use the electro-optic constant r33 of a poled polymer.

FIG. 8 is a schematic view showing a hologram recording method of the present invention.

FIG. 9 is an overall schematic diagram of an example of an interferometer that can use the hologram recording method of the present invention.

FIG. 10 is a schematic view of a method for reproducing a hologram recorded on a hologram recording element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording layer 2, 2 'Transparent electrode layer 3, 3' Insulating protective layer 4 Insulating layer 5 Transparent substrate 6 Arrow indicating the poling direction 7 Object light for recording 7 'Reference light for recording 8 Interference fringe 9 Power supply 10 Switch 11 Reference light for reproduction 12 Diffracted reproduction light 20 Subject 21 Laser light source 22, 26 Mirror 23 Shutter 24 Beam splitter 25, 27 Lens 28 Timer device

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yusuke Ozaki 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (72) Inventor Norio Sonoda 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-2455782 (JP, A) (58) Fields investigated (Int. . ^7, DB name) G03H 1/00 - 1/30 G03F 7/00

Claims (4)

(57) [Claims] 1. A hologram recording material comprising a polymer composition having a structure having a photoconductive element, an element exhibiting secondary hyperpolarization, and an electron or hole trapping element and having no center of inversion symmetry. A hologram recording material, wherein the polymer composition is at least one selected from the following (I) to (V). (I) 2- (N-carbazolyl) ethyl acrylate and 2- [4- (β, β-dicyanovinyl) phenoxy]
Polymer composition containing a copolymer of ethyl methacrylate, dibutyl phthalate, and trinitrofluorenone (II) 3- (N-ethylcarbazolylmethyl) acrylate and 2- {N- [4- (β-cyano-β) -Ethoxycarbonylvinyl)]-N-methylanilinodiethyl
Polymer composition containing methacrylate copolymer, dibutyl phthalate, trinitrofluorenone (III) 2- (N-carbazolyl) ethyl acrylate and 2- {N- [4- (β-cyano-β-ethoxycarbonylvinyl) )]-N-methylanilinodiethyl methacrylate copolymer, polymer composition containing trinitrofluorenone (IV) Co-polymerization of 2- [4- (β, β-dicyanovinyl) phenoxy] ethyl methacrylate and methyl methacrylate Polymer composition containing a copolymer, a polycarbonate, a vinyl carbazole oligomer, N, N'-diphenyl-N ', N'-bis (3-toluyl) -4,4'-diaminobiphenyl (V) polyvinyl carbazole, N, N-diethyl-4
-A polymer composition containing nitroaniline, dibutyl phthalate, and tetranitrofluorenone 2. A recording layer comprising a polymer composition having a photoconductive element, an element exhibiting secondary hyperpolarization, and an electron or hole trapping element and having a structure having no inversion symmetry center. A hologram recording element provided with a transparent electrode layer on both sides, wherein the polymer composition is at least one selected from the following (I) to (V). (I) 2- (N-carbazolyl) ethyl acrylate and 2- [4- (β, β-dicyanovinyl) phenoxy]
Polymer composition containing a copolymer of ethyl methacrylate, dibutyl phthalate, and trinitrofluorenone (II) 3- (N-ethylcarbazolylmethyl) acrylate and 2- {N- [4- (β-cyano-β) -Ethoxycarbonylvinyl)]-N-methylanilinodiethyl
Polymer composition containing methacrylate copolymer, dibutyl phthalate, trinitrofluorenone (III) 2- (N-carbazolyl) ethyl acrylate and 2- {N- [4- (β-cyano-β-ethoxycarbonylvinyl) )]-N-methylanilinodiethyl methacrylate copolymer, polymer composition containing trinitrofluorenone (IV) Co-polymerization of 2- [4- (β, β-dicyanovinyl) phenoxy] ethyl methacrylate and methyl methacrylate Polymer composition containing a copolymer, a polycarbonate, a vinyl carbazole oligomer, N, N'-diphenyl-N ', N'-bis (3-toluyl) -4,4'-diaminobiphenyl (V) polyvinyl carbazole, N, N-diethyl-4
-A polymer composition containing nitroaniline, dibutyl phthalate, and tetranitrofluorenone 3. A method for manufacturing a hologram recording element, comprising at least one of the following steps i. To iv. (I) a solution preparation step of preparing a solution of a polymer composition including an element having photoconductivity, an element exhibiting secondary hyperpolarization, and an electron or hole trapping element; A film forming step of applying and drying a solution to form a film of the polymer composition; (iii) preparing a plurality of films prepared in the film forming step and a transparent substrate having a transparent electrode layer formed on one surface side; A step of preparing a plurality of sheets, melting and press-molding them in a state where they are overlapped so as to sandwich a plurality of films on a transparent substrate so that the film and the transparent electrode layer are in contact with each other, and (iv) glass of the polymer composition An electric field is applied between the transparent electrode layers while heating the recording layer to a temperature close to or higher than the transition temperature, and then cooled and polarized. 4. The hologram recording device according to claim 1, wherein
A method for recording a recording material, comprising: a photoconductive element; and an element exhibiting secondary hyperpolarization, and both sides of a recording layer comprising a polymer composition having a structure having no center of inversion symmetry. A hologram recording method for recording a hologram by irradiating coherent light from both sides of the recording layer in a state where a DC voltage is applied between the transparent electrode layers provided in the hologram.