JP2001281450A - Optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element having excellent moldability, workability, flexibility, lightweight performance, thin film formability and handleability. SOLUTION: The optical element contains a polylactic resin and has a shape of a film, a sheet or a fiber. Since the optical element has the excellent moldability, workability, flexibility, lightweight performance, thin film formability and handleability, the optical element can widely be used in various fields.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element comprising a polylactic acid resin and having a film, sheet or fiber shape.

[0002]

2. Description of the Related Art As an optical rotator for rotating the azimuth of linearly polarized light or elliptically polarized light such as a half-wave plate, a rotatory crystal plate or a retardation plate, a birefringent crystal such as quartz or a calcite is used. What consists of a crystalline crystal is known. However, productivity is very low because it requires advanced technology and a great deal of labor and time for crystal adjustment and polishing processing for improving accuracy, and it is difficult to form a large area due to poor flexibility. There was a problem.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an optical element having good moldability.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors can solve the above problems by using a film, sheet or fiber containing a polylactic acid resin as an optical element. And found the present invention based on the findings. That is, the present invention is specified by the matters described in the following [1] to [14].

[1] An optical element comprising a polylactic acid-based resin and having a film or sheet shape.

[2] An optical element having a fiber shape, comprising a polylactic acid-based resin.

[3] The optical element according to [1] or [2], wherein the polylactic acid-based resin is polylactic acid.

[4] The optical element according to any one of [1] to [3], wherein the isomer content in the repeating unit derived from lactic acid in the polylactic acid-based resin is 0 to 10 mol%.

[5] The optical element according to any one of [1] to [4], comprising an additive.

[6] The additives include hydroxycarboxylic acid, polycarboxylic acid, anhydride of polycarboxylic acid, polyamide of polycarboxylic acid, polyhydric alcohol, polyhydric amine,
The optical element according to [5], which is at least one compound selected from the group consisting of a sugar, an aminocarboxylic acid, a polypeptide, and a liquid crystal compound.

[7] The optical element according to [5] or [6], wherein the additive has optical activity.

[8] The optical element according to any one of [5] to [7], wherein the composition ratio of the additive is 0.001 to 30% by weight based on the weight of the polylactic acid-based resin.

[9] The optical element according to any one of [1] to [8], which has optical rotation.

[10] Optical rotation is 10 to 10000 °
The optical element according to [9], which exhibits an optical rotation of / 1 mm.

[11] The optical element according to [9] or [10], which has optical rotation in at least two axial directions.

[12] An optical modulator according to any one of [1] to [11].

[13] The drive frequency of light modulation is 1 MH
The light modulation device according to [12], wherein the frequency is z to 100 GHz.

[14] The drive voltage for light modulation is 0.01
The light modulation device according to [12] or [13], which has a kV / m to 1 MV / m.

[0019]

Embodiments of the present invention will be described below in detail.

[Polylactic acid-based resin] In the present invention, polylactic acid-based resin refers to polylactic acid, a copolymer of lactic acid and a polyfunctional compound capable of copolymerization such as hydroxycarboxylic acid, and lactic acid and a polyhydric alcohol and a polyhydric alcohol. Carboxylic acid copolymers,
And mixtures thereof. Among these polylactic acid-based resins, polylactic acid which is a homopolymer is preferable.
-Polylactic acid is more preferred. In the case of a mixture, a compatibilizer may be contained. When the polylactic acid-based resin is a copolymer, the mode of arrangement of the copolymer is a random copolymer,
Any of an alternating copolymer, a block copolymer, and a graft copolymer may be used. Furthermore, these may be at least partially cross-linked with a polyvalent isocyanate such as xylylene diisocyanate or 2,4-tolylene diisocyanate, or a cross-linking agent such as cellulose or a polysaccharide such as acetyl cellulose or ethyl cellulose. A part may have any structure such as a linear, annular, branched, star-like, and three-dimensional network structure, and is not limited at all.

[Lactic acid] Lactic acid as a raw material includes L-lactic acid and D-lactic acid.
-Lactic acid, DL-lactic acid, or a mixture thereof. When lactide, which is a cyclic dimer of lactic acid, is used as a raw material of the resin, L-lactide, D-lactide, meso-lactide, or And mixtures thereof. A lactic acid polymer having a desired optical purity can be polymerized by various combinations of these optical isomer raw materials and reaction conditions, but the isomer content is 0 to 10%.
Is preferable, 0 to 5% is more preferable, and 0 to 2% is further preferable. For example, when the polylactic acid-based resin is L-polylactic acid, the content of D-lactic acid is preferably 0 to 10%, more preferably 0 to 5%, and still more preferably 0 to 2%.

[Copolymerizable Polyfunctional Compound] Examples of the copolymerizable polyfunctional compound include glycolic acid,
Dimethyl glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxypropanoic acid, 3-hydroxypropanoic acid, 2-hydroxyvaleric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid,
5-hydroxyvaleric acid, 2-hydroxycaproic acid, 3
-Hydroxycaproic acid, 4-hydroxycaproic acid,
Hydroxycarboxylic acids such as 5-hydroxycaproic acid, 6-hydroxycaproic acid, 6-hydroxymethylcaproic acid, and mandelic acid; glycolide, β-methyl-δ-
Cyclic esters such as valerolactone, γ-valerolactone, ε-caprolactone; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, undecandioic acid, dodecanedioic acid, terephthalic acid Polyhydric carboxylic acids such as, and their anhydrides; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, tetramethylene glycol, 1,4 -Polyhydric alcohols such as hexane dimethanol; polysaccharides such as cellulose And aminocarboxylic acids such as α-amino acids. These copolymerizable polyfunctional compounds may be one kind or a mixture of two or more kinds, and when having an asymmetric carbon, L-form, D-form, and a mixture of any ratio thereof may be used. Good.

[Production method of polylactic acid-based resin] The production method of the polylactic acid-based resin used in the present invention is not particularly limited, but is described in, for example, JP-A-59-096123 and JP-A-7-033861. A method of directly dehydrating and condensing lactic acid, or US Pat. No. 4,057,3
No. 57, Polymer Bulletin, Vol. 14,
491-495 (1985), Makromol.
Chem. 187, 1611-1628 (198
6 years) and the like, and a method of ring-opening polymerization using lactide, which is a cyclic dimer of lactic acid, and the like.

[Weight average molecular weight of polylactic acid-based resin] The weight-average molecular weight (Mw) of the polylactic acid-based resin used in the present invention is not particularly limited, but may range from 10,000 to 1
Preferably 10 million, more preferably 30,000 to 3 million,
50,000 to 1,000,000 is more preferable. The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the polylactic acid-based resin used in the present invention are determined according to the type of raw material, type of solvent, type and amount of catalyst, reaction temperature, reaction time The reaction system can be controlled to a desired one by appropriately selecting reaction conditions such as the degree of dehydration of the reaction system. The polylactic acid-based resin used in the present invention can be widely used as an optical element because of its high transparency.

[Optical rotation of polylactic acid-based resin] The polylactic acid-based resin used in the present invention has an asymmetric carbon in its main chain.
By appropriate structure control, high optical rotation can be exhibited. When used as an optical rotator, the optical rotation is not particularly limited, but is usually preferably 10 to 10000 ° / 1 mm.

[Additives] Additives can be added to the polylactic acid resin used in the present invention for the purpose of improving optical rotation and other physical properties. Specific examples of such additives include, for example, glycolic acid, dimethyl glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxypropanoic acid, 3-hydroxypropanoic acid, and 2-hydroxybutyric acid. Valeric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxycaproic acid, 3-hydroxycaproic acid, 4-hydroxycaproic acid, 5-hydroxycaproic acid, 6-hydroxycaproic acid , 6-hydroxymethylcaproic acid, hydroxycarboxylic acids such as mandelic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, undecandioic acid, dodecanedioic acid, terephthalic acid And the like, and their anhydrides and their monomers. De and these diamides, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl -
1,5-pentanediol, 2,3-butanediol,
Polyhydric alcohols such as 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, tetramethylene glycol, 1,4-hexanedimethanol, glycerin; ethylenediamine, propanediamine, butane Polyamines such as diamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine; glyceraldehyde, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, and growth , Idose, galactose, talose, fructose, 2-deoxyribose; alditols such as mannitol and glucitol; inositol, myo-inositol; glucosamine Monosaccharides, sucrose, lactose, maltose, cellobiose, a disaccharide trehalose, trisaccharides raffinose, starch, amylose, amylopectin, cellulose, lignin, chitin,
Polysaccharides such as chitosan, linaken, pectin, heparin and derivatives thereof; alanine, valine, leucine, isoleucine, methionine, tryptophan, phenylalanine, proline, glycine, serine, threonine, cysteine, tyrosine, asparagine, glutamine, lysine,
Histidine, arginine, aspartic acid, glutamic acid, L-ornithine, β-alanine, γ-aminobutyric acid,
Amino acids and amino acid derivatives such as ω-esters of acidic amino acids, N-substituted basic amino acids, and aspartic acid-L-phenylalanine dimer (aspartame);
Aminosulfonic acids such as cysteic acid, aminocarboxylic acids such as α-amino acids, polylysine, polyglutamic acid,
Polyaspartic acid, polypeptides such as proteins and derivatives thereof; cholesteryl bromide, cholesteryl-n
-Hexyl ether, cholesteryl-n-heptanoate, cholesteryl-n-heptylcarbonate, cholesteryl-n-heptylmercaptocarbonate, cholesteryl benzoate, cholesteryl-ω-phenylheptanoate, cholesteryl elcate, 4-n-dodecyloxy-1-naphthyridine- A halide of cholesterol such as cholesteryl-p-aminobenzoate,
Fatty acid ester, carbonate ester, N- (4-ethoxybenzylidene) -4- (2-methylbutyl) aniline,
-Ethoxy-4 '-(2-methylbutyl) azobenzene, 4-ethoxy-4'-(2-methylbutyl) azoxybenzene, 4- (2-methylbutyl) benzoic acid-4 '
-N-hexyloxyphenyl ester, 4-n-heptoxy-4 '-(2-methylbutyloxycarbonyl)
Biphenyl, 4- [4- (2-methylbutyl) benzoyloxy] benzoic acid-4′-n-pentylphenyl ester, 4- [4- (2-methylbutyl) benzoyloxy] benzoic acid-4′-cyanophenyl ester, 4-
[4- (2-methylbutyl) benzoyloxy] benzoic acid-4′-nitrophenyl ester, 4- [4- (3-
Methylpentyl) benzoyloxy] benzoic acid-4'-
Methylphenyl ester, 4- (2-methylbutyl)-
4'-cyanobiphenyl, 4- (3-methylpentyl)
-4'-cyanobiphenyl, 4- (3-methylpentyl) -4'-cyanobiphenyl, 4- [4- (2-methylbutyl) phenyl] benzoic acid-4'-butylphenyl ester, 4- [4- ( 2-methylbutyl) phenyl]
Benzoic acid-4′-cyanophenyl ester, trans
-4- (2-methylbutyl) cyanohexylcarboxylic acid-4'-cyanobiphenyl ester, 4-n-hexyloxybenzoic acid-4 '-(2-methylbutoxycarbonyl) phenyl ester, 4- (4-methylbutyl)-
And liquid crystal compounds such as 4 ″ -cyano-p-terphenyl and cholesteric liquid crystal compounds.

[Composition Ratio of Additives] The composition ratio of the additives to be added to the polylactic acid resin used in the present invention is not particularly limited as long as it can substantially exert its function.
0.001 to 30 based on the weight of the polylactic acid-based resin
%, Preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight. By adding these additives, for example, optical rotation can be imparted in at least two axial directions. In this case, the additives are preferably compounds having optical activity.

[Applications] The optical element according to the present invention can be used, for example, in optical communication systems, optical switching systems, and optical measurement systems in the fields of optical rotators, wave plates, polarizing plates, optical deflectors,
Phase difference plate, waveguide, lens, optical fiber, optical fiber coating material, light emitting element, light modulation element, optical amplification element, optical switch, optical shutter, dimmer, dimmer panel, magneto-optical storage element, optical memory, hologram And other recording media, optical arithmetic elements, barcodes, solar cells, photodetectors, semiconductor lasers, solid-state lasers, LEDs, ELs, spatial light modulators, wavelength conversion elements, optical isolators, photorefractive, PSHB, liquid crystal panels, heads It can be used as a display material for an up display or the like. It can be used as a light modulation element by utilizing optical rotation, and the driving frequency is preferably 1 MHz to 100 GHz, and the driving voltage is preferably 0.01 kV / m to 1 MV / m. Further, by having optical rotation in at least two axial directions, it can be used as an optical element such as a more advanced arithmetic element. When used as an optical element, it can be used in combination with another optical element such as a polarizing plate.

[Shape] The shape of the optical element according to the present invention is as follows.
Films, sheets and fibers. As used herein, a film refers to a thin, plate-like molded product having a thickness of less than 0.25 mm, and a sheet refers to a thicker product. Fiber refers to an elongated linear solid.

[Molding Method] The optical element according to the present invention comprises:
Manufactured by known molding methods, specifically, injection molding, extrusion, blow molding, inflation molding, vacuum molding, melt film forming, dry film forming, wet film forming, melting A spinning method, a dry spinning method, a wet spinning method and the like can be mentioned.

[Processing into a film-like shape] When processing into a film-like shape, a polylactic acid-based resin is converted into an unstretched film using an extruder equipped with a T-die, a circular die, or the like. Can be molded. Further, if necessary, the obtained unstretched film is uniaxially stretched, or sequentially biaxially stretched by roll stretching and tenter stretching, simultaneously biaxially stretched by tenter stretching, biaxially stretched by tubular stretching, or the like. By stretching, a biaxially stretched film can be produced. For example, a stretched film by sequential biaxial stretching combining roll stretching and tenter stretching is manufactured as follows. The polylactic acid-based resin is heat-treated at a temperature of 50 to 130 ° C., and is dried and crystallized. Next, 130 to 25 with an extruder equipped with a T die.
After melt extrusion at a temperature of 0 ° C., the film is quenched with a casting roll at a temperature of 60 ° C. or less to form a film. In this case, it is preferable to use an air knife or an electrostatic application device in order to improve the flatness by bringing the molten film into close contact with the roll. Next, the obtained film is passed through a take-up machine, and is then moved to a longitudinal stretching machine for 3 hours.
After stretching longitudinally 1.3 to 5 times, preferably 2 to 4 times at a temperature of 0 to 80 ° C, 1.3 to 5 times, preferably 2 to 4 times at a temperature of 40 to 80 ° C with a tenter. Stretch horizontally. When heat resistance (heat shrinkage resistance) of the stretched film is required, it is preferable to heat-fix the stretched film in a tenter at a temperature of 80 to 150 ° C. for 3 to 120 seconds under tension.

[Processing into Fiber Shape] In the case of processing into a fiber shape, kneading and melting are performed using an extruder or the like equipped with a spinning die, and formed into fibers through a spinneret. I do. If necessary, the fiber can be drawn and oriented, and the oriented fiber can be annealed and further subjected to heat treatment. The spinning temperature may be at least the melting point of the resin and less than the decomposition temperature. Usually, it is preferably from 120C to 250C. The stretching temperature is
It is selected on the basis of the glass transition temperature of the fiber, but is usually preferably about 15 to 80 ° C. More preferably, it is 25 to 70 ° C. The draw ratio is preferably 3 to 20 times, more preferably 3 to 20 times, in the longitudinal direction of the fiber.
It is 10 times. The drawn fiber has tensile strength,
Annealing and heat treatment are preferably performed to make the dimensional stability characteristics uniform. Annealing is 0.5
10 to 10% under relaxation, or preferably 40 to 1 under tension
It is preferable to carry out at 30 ° C. for about 0.01 to 30 seconds. After annealing, heat treatment is performed at 40-150 ° C, 1
Under tension at a reduced pressure of 30 to 100,000 Pa,
It is preferably performed for 1 to 72 hours. To obtain particularly high orientation, gel spinning, liquid crystal spinning, vibration heat drawing,
Methods such as a dielectric heating stretching method, a two-stage stretching method (solid phase coextrusion, tensile stretching), stretching under pressure, and a zone heat treatment method can be used. The resin of the present invention thus obtained can be further processed into a desired shape by performing cutting, polishing and the like as necessary.

[Concept of the term "fiber"] The concept of the term "fiber" used in the specification of the present application is not particularly limited. Third Edition] [Issuer; Plastic Age Co., Ltd., Supervisor: Susumu Nagai,
(September 10, 1989), the concept of commentary on "fiber", "fiber", "filament", and "strand".

[Other Additives] The polylactic acid-based resin used in the present invention may contain other additives other than the above-mentioned additives according to the purpose. Specific examples of additives include, for example, plasticizers, heat stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, pigments, colorants, various fillers, antistatic agents, release agents, fragrances, lubricants, Examples include a burning agent, a foaming agent, a filler, an antibacterial agent, an antibacterial agent, and a nucleating agent.

[0035]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.

[Production Example 1] 100 parts by weight of L-lactide, 0.01 parts by weight of stannous octoate, and 0.03 parts by weight of lauryl alcohol were put into a thick cylindrical stainless steel polymerization vessel equipped with a stirrer. After charging and degassing under vacuum for 2 hours, the atmosphere was replaced with nitrogen gas. The mixture was heated at 200 ° C. for 3 hours with stirring under a nitrogen atmosphere. While maintaining the temperature as it was, the air was gradually degassed by a vacuum pump through an exhaust pipe and a glass receiver, and the pressure inside the reaction vessel was reduced to 3 mmHg. One hour after the start of degassing, the distillation of the monomer and low molecular weight volatiles was stopped.
The polymer was drawn out from the lower part of the container into a strand and pelletized to obtain polylactic acid. The weight average molecular weight Mw is 1
It was 36,000.

[Production Example 2] 90% L-lactic acid 1 was placed in a 1 liter reactor equipped with a Dien-Stark trap.
Water was distilled off while stirring 00 g at 150 ° C. and 50 mmHg for 3 hours, and 0.062 g of tin powder was added.
The mixture was further stirred at 30 ° C. and 30 mmHg for 2 hours to be oligomerized. 0.288 g of tin powder and 211 g of diphenyl ether were added to this oligomer, azeotropic dehydration was performed at 150 ° C. and 35 mmHg, the distilled water and the solvent were separated by a water separator, and only the solvent was returned to the reactor. After 2 hours, the solvent to be returned to the reactor was passed through a column packed with 460 g of molecular sieve 3A, and then returned to the reactor.
The reaction was performed at 35 ° C and 35 mmHg for 40 hours to obtain a solution of polylactic acid. Diphenyl ether dehydrated to this solution 4
After adding 40 g, the mixture was diluted and cooled to 40 ° C., and the precipitated crystals were filtered, washed with 100 g of n-hexane three times, and dried at 60 ° C. and 50 mmHg. 0.5 of this powder
120 g of N hydrochloric acid and 120 g of ethanol were added, stirred at 35 ° C. for 1 hour, filtered, and dried at 60 ° C. and 50 mmHg to obtain polylactic acid. The weight average molecular weight Mw of this polylactic acid was 145,000.

Example 1 The polylactic acid obtained in Production Example 1 was melt-extruded at 240 ° C. using an extruder and spun. The obtained fiber was stretched 5 times in the length direction at 50 ° C., then annealed under tension at 60 ° C. for several seconds, and further heat-treated at 110 ° C. under reduced pressure for 3 hours. When the optical rotation of this fiber was measured, it was 30 ° / 1 mm, and the fiber had flexibility.

Example 2 A fiber was obtained from the polylactic acid obtained in Production Example 2 in the same manner as in Example 1. When the optical rotation of this fiber was measured, it was 20 ° / 1 mm, and the fiber had flexibility.

Example 3 The polylactic acid obtained in Production Example 1 was melt-extruded at 240 ° C. by an extruder equipped with a T-die, and then rapidly cooled by a casting roll to form a film. The obtained unstretched film was stretched four times in a longitudinal stretching machine at a temperature of 60 ° C. Subsequently, it was heat-set at 110 ° C. for 60 seconds under tension in a tenter. The measured optical rotation was 21 ° / 1 mm, indicating that the film had flexibility.

Comparative Example 1 The optical rotation of quartz (α-SiO 2) was measured and found to be 25 ° / 1 mm, indicating no flexibility.

[0042]

According to the optical element of the present invention, moldability, workability,
Since it is excellent in flexibility, light weight, thin film property, and handleability, it can be widely used in various fields.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) G02B 6/00 391 G02B 6/00 391 G02F 1/061 501 G02F 1/061 501 // (C08L 67/04 (C08L 67/04 89:00) 89:00) (C08L 67/04 (C08L 67/04 5:00) 5:00) (72) Inventor Yoshiro Tami 4-16-4 Jonan, Yonezawa City, Yamagata Prefecture Yamagata University F-term (reference) 2H049 BA08 BB42 BB50 BC03 BC22 BC23 BC25 2H050 AB42Z AD16 2H079 AA02 BA02 CA08 DA07 4F071 AA08 AA43 AA70 AC02 AC05 AC09 AC10 AC12 BA01 BB06 BB07 BB08 BB09 BC01 EN016 016 016 016 GP00

Claims (14)

[Claims] 1. An optical element having a film or sheet shape, comprising a polylactic acid-based resin. 2. An optical element having a fiber shape and comprising a polylactic acid-based resin. 3. The optical element according to claim 1, wherein the polylactic acid-based resin is polylactic acid. 4. The optical element according to claim 1, wherein the isomer content of the repeating unit derived from lactic acid in the polylactic acid-based resin is 0 to 10 mol%. 5. The optical element according to claim 1, further comprising an additive. 6. An additive comprising a hydroxycarboxylic acid, a polycarboxylic acid, an anhydride of a polycarboxylic acid, a polyamide of a polycarboxylic acid, a polyhydric alcohol, a polyamine, a sugar, an aminocarboxylic acid, and a polycarboxylic acid. The optical element according to claim 5, wherein the optical element is at least one compound selected from the group consisting of a peptide and a liquid crystal compound. 7. The optical element according to claim 5, wherein the additive has optical activity. 8. The optical element according to claim 5, wherein the composition ratio of the additive is 0.001 to 30% by weight based on the weight of the polylactic acid-based resin. 9. The optical element according to claim 1, wherein the optical element has optical rotation. 10. The optical rotation is 10 to 10000 ° / 1m.
The optical element according to claim 9, which exhibits an optical rotation of m. 11. The optical element according to claim 9, having optical rotation in at least two axial directions. 12. The light modulation device according to claim 1, wherein: 13. The driving frequency of light modulation is from 1 MHz to 1 MHz.
13. The light modulation device according to claim 12, which has a frequency of 00 GHz. 14. A driving voltage for light modulation is 0.01 kV /
The light modulation device according to claim 12, wherein the light modulation device has a value of m to 1 MV / m.