Claims
- 1. A thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR19## where PV is a main chain polyvinyl unit; S' is a pendant spacer group having a linear chain length of between about 2-12 atoms; X is an electron-donating group; Y is ##STR20## and Z is an electron withdrawing group; and the polymer has a glass transition temperature in the range between about 40.degree.-250.degree. C.
- 2. A thin film optical waveguide medium in accordance with claim 1 wherein the polyvinyl polymer contains a recurring acrylate monomeric unit.
- 3. A thin film optical waveguide medium in accordance with claim 1 wherein the polyvinyl polymer contains a recurring vinyl halide monomeric unit.
- 4. A thin film optical waveguide medium in accordance with claim 1 wherein the polyvinyl polymer contains a recurring vinyl carboxylate monomeric unit.
- 5. A thin film optical waveguide medium in accordance with claim 1 wherein the polyvinyl polymer contains a recurring alkene monomeric unit.
- 6. A thin film optical waveguide medium in accordance with claim 1 wherein the polyvinyl polymer contains a recurring arylvinyl monomeric unit.
- 7. A thin film optical waveguide medium in accordance with claim 1 wherein the polymer is characterized by an external field-induced alignment of pendant side chains.
- 8. A thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR21## where CP is a main chain condensation polymer unit; S' is a pendant spacer group having a linear chain length of between about 2-12 atoms; X is an electron-donating group; Y is ##STR22## and Z is an electron withdrawing group; and the polymer has a glass transition temperature in the range between about 40.degree.-250.degree. C.
- 9. A thin film optical waveguide medium in accordance with claim 8 wherein the main chain condensation polymer is a polyester structure.
- 10. A thin film optical waveguide medium in accordance with claim 8 wherein the main chain condensation polymer is a polyamide structure.
- 11. A thin film optical waveguide medium in accordance with claim 8 wherein the polymer is characterized by an external field-induced alignment of pendant side chains.
- 12. A thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR23## where PS is a main chain polysiloxane unit; S' is a pendant spacer group having a linear chain length of between about 2-12 atoms; X is an electron-donating group; Y is ##STR24## and Z is an electron withdrawing group; and the polymer has a glass transition temperature in the range between about 40.degree.-250.degree. C.
- 13. A thin film optical waveguide medium in accordance with claim 12 wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR25## where R is a C.sub.1 -C.sub.10 hydrocarbyl substituent; S' is a pendant spacer group having a linear chain length of between about 2-12 atoms; X is an electron-donating group; Y is ##STR26## and Z is an electron withdrawing group; and the polymer has a glass transition temperature in the range between about 40-250.degree. C.
- 14. A thin film optical waveguide medium in accordance with claim 12 wherein the polymer is characterized by an external field-induced alignment of pendant side chains.
- 15. A thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR27## where m and m.sup.1 are integers which total at least 10; R is hydrogen or a C.sub.1 -C.sub.4 alkyl; n is an integer having a value of 2-8; X is oxygen, sulfur or an amino or cycloamino group; R.sup.2 is a C.sub.1 -C.sub.12 alkyl or cycloalkyl group; Y is ##STR28## and Z is an electron-withdrawing group; and the polymer has a glass transition in the range between about 50.degree.-200.degree. C.
- 16. A thin film optical waveguide medium in accordance with claim 15 wherein the X substituent in the formula has the structure ##STR29##
- 17. A thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR30## where m and m.sup.1 are integers which total at least 10; R is hydrogen or C.sub.1 -C.sub.4 alkyl; L is --NR.sup.1 -- or ##STR31## R.sup.1 is hydrogen or a C.sub.1 -C.sub.4 alkyl group; Q is nitrogen or a --CH-- radical; R.sup.2 is a C.sub.1 -C.sub.12 alkyl or cycloalkyl group; the m monomer comprises between about 30-70 mole percent of the total monomers; and the polymer has a glass transition temperature in the range between about 50.degree.-200.degree. C.
- 18. A thin film optical waveguide medium in accordance with claim 17 the polymer additionally contains recurring units of a third monomer.
- 19. A thin film optical waveguide medium in accordance with claim 17 wherein the polymer has an external field-induced alignment of pendant side chains.
- 20. A thin film optical waveguide medium in accordance with claim 17 wherein the waveguide medium has a two-dimensional channel structure for single mode wave transmission.
- 21. A thin film optical waveguide medium in accordance with claim 17 wherein the waveguide medium has a spatial periodic structure of aligned polymer side chains for phase matching of propagating wave energy.
- 22. A thin film optical waveguide medium in accordance with claim 17 wherein the waveguide medium has a spatial periodic structure of aligned polymer side chains for phase matching of propagating wave energy, and the spatial periodicity of aligned polymer side chains is bidirectional in structure.
- 23. A thin film optical waveguide medium in accordance with claim 17 wherein the thin film is in a laminated assembly with an upper organic cladding layer and a lower organic cladding layer, each of which has a lower index of refraction than the thin film waveguide component, and which exhibits second order nonlinear optical susceptibility .chi..sup.(2).
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
This is a continuation-in-part of copending application Ser. No. 915,179, filed Oct. 3, 1986, now U.S. Pat. No. 4,915,491.
The present patent application has subject matter related to the disclosures of copending patent application Ser. No. 148,262, U.S. Pat. No. 4,913,844 filed Jan. 25, 1988; patent application Ser. No. 405,503, filed Sept. 11, 1989; patent application Ser. No. (477,283), filed Feb. 7, 1990; and patent application Ser. No. (477,267), filed Feb. 7, 1990.
Polymers with a comb structure of pendant side chains are a new class of organic materials which exhibit interesting optical properties.
Comb-like liquid crystalline polymers are described in Eur. Polym J., 18, 651 (1982); Advanced Polymer Science, Liquid Crystal Polymers II/III, Springer-Verlag, New York (1984), pages 215-220; and in United States Patent Numbers 4,293,435 and 4,631,328. The disclosed polymeric structures have been developed for their mesogenic optical properties which have prospective utility in opto-electronic display devices.
In U.S. Pat. Nos. 4,694,066; 4,755,574; and 4,762,912 liquid crystalline polymers are described which have pendant side chains which exhibit nonlinear optical susceptibility, in addition to mesogenic properties. U.S. Pat. No. 4,792,208 discloses nonlinear optically responsive organic compounds and side chain polymers in which the molecular dipoles have an electron donor moiety linked through a conjugated .pi. bonding system to an electron acceptor sulfonyl moiety. Japanese patent No. 88175834 discloses an acrylate polymer which has nitro(ethylhydroxyethylamino)azobenzene side chains.
Nonlinear optical properties of organic and polymeric materials was the subject of a symposium sponsored by the ACS division of Polymer Chemistry at the 18th meeting of the American Chemical Society, September 1982. Papers presented at the meeting are published in ACS Symposium Series 233, American Chemical Society, Washington, D.C. 1983.
Thin films of organic or polymeric materials with large second order nonlinearities in combination with silicon-based electronic circuitry have potential as systems for laser modulation and deflection, information control in optical circuitry, and the like.
Other novel processes occurring through third order nonlinearity such as degenerate four-wave mixing, whereby real-time processing of optical fields occurs, have potential utility in such diverse fields as optical communications and integrated circuit fabrication.
Liquid crystalline side chain polymers which exhibit nonlinear optical properties are suitable for application as a nonlinear optical component in optical light switch and light modulator devices. One disadvantage of a liquid crystalline side chain polymer optical medium is a loss of transmission efficiency due to light scattering by deviations from ideal mesogenic order.
There is continuing interest in the theory and practice of optically responsive polymers which are characterized by an oriented state of comb-like side chain structures.
There is also an increasing research effort to develop new nonlinear optical organic systems for prospective novel phenomena and devices adapted for laser frequency conversion, information control in optical circuitry, light valves and optical switches. The potential utility of organic materials with large second order and third order nonlinearities for very high frequency application contrasts with the bandwidth limitations of conventional inorganic electrooptic materials.
Accordingly, it is an object of this invention to provide optically responsive monomers and polymers.
It is another object of this invention to provide polyvinyl copolymers having side chains which exhibit nonlinear optical response.
It is a further object of this invention to provide optical waveguide media comprising a thin film of an amorphous polymer with nonlinear optically-responsive pendant side chains which can be uniaxially aligned by an external field.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.
One or more objects of the present invention are accomplished by the provision of a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter.
In another embodiment this invention provides a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR2## where P' is a polymer main chain unit; S' is a pendant spacer group having a linear chain length of between about 2-12 atoms; M' is an organic structure which exhibits second order nonlinear optical susceptibility .beta.; and the polymer has a weight average molecular weight in the range between about 5000-200,000.
In a preferred embodiment an invention thin film optical waveguide medium consists of a side chain polymer which is characterized by an external field-induced orientation and alignment of pendant side chains.
In the above represented side chain polymer formula, the main chain can be a structural type such as polyvinyl, polyoxyalkylene, polysiloxane, polycondensation, and the like.
A present invention polymer having pendant side chains which exhibit nonlinear optical susceptibility .beta. is formed into a nonlinear optical medium, such as a transparent film or coating on a substrate. A polymer can be applied to a supporting substrate by conventional means, such as spin coating, spraying, Langmuir-Blodgett deposition, and the like.
A film or coating fabricated with a present invention polymer initially exhibits third order nonlinear optical susceptibility. A thin film optical waveguide medium of the present invention after fabrication is subjected to an external field to orient and align uniaxially the polymer side chains. In one method the polymer medium is heated close to or above the polymer glass transition temperature T.sub.g, then an external field (e.g., a DC electric field) is applied to the medium of mobile polymer molecules to induce uniaxial molecular alignment of polymer side chains parallel to the applied field, and the medium is cooled while maintaining the external field effect.
By this method a present invention thin film optical waveguide medium has a stable uniaxial alignment of polymer side chains. The poled optical medium exhibits a second order nonlinear optical susceptibility .chi..sup.(2). A present invention poled thin film optical medium is capable of exhibiting a .chi..sup.(2) level of 1.times.10.sup.-8 esu or higher as measured at 1.34 .mu.m excitation wavelength.
The term "electron-donating" as employed herein refers to substituents which contribute electron density to the .pi.-electron system when the conjugated electronic structure is polarized by the input of electromagnetic energy.
The term "electron-withdrawing" as employed herein refers to electronegative organic substituents which attract electron density from the .pi.-electron system when the conjugated electron structure is polarized by the input of electromagnetic energy.
Illustrative of electron-donating substituents are amino, alkylamino, dialkylamino, 1-piperidino, 1-piperazino, 1-pyrrolidino, acylamino, hydroxyl, thiolo, alkylthio, arylthio, alkoxy, aryloxy, acyloxy, 1,2,3,4-tetrahydroquinolinyl, and the like.
Illustrative of electron-withdrawing substituents are nitro, cyano, trifluoromethyl, acyl, carboxy, alkanoyloxy, aroyloxy, carboxamido, alkoxysulfonyl, aryloxysulfonyl, and structures such as --CH.dbd.C(CN).sub.2, --C(CN).dbd.C(CN).sub.2, --SO.sub.2 CF.sub.3, ##STR3## or --CF.sub.3.
The term "external field" as employed herein refers to an electric, magnetic or mechanical stress field which is applied to a substrate of mobile polymer molecules, to induce dipolar alignment of the polymer molecules and/or polymer side chains parallel to the field.
The term "amorphous" as employed herein refers to a transparent polymeric optical medium which exhibits only short range translational and orientational order of internuclear distance vectors r.sub.ij. Short range order refers to order in which there is preferred internuclear distances between nearest neighbor atoms as occurs in a liquid. This is distinct from long range order, in which atoms lie on preferred sites within a repeating unit cell with both three dimensional translational and rotational order as occurs in a crystalline material. This is also distinct from order in which atoms occupy preferred sites which repeat with long range translational and/or rotational order in less than three dimensions for both translation and/or rotation as occurs in liquid crystalline materials or plastic crystals.
Long range order requires repetition over several unit cells. The number of unit cells determines the range of ordering. For crystals this repetition of unit cells is known as the crystallite size. Materials may possess long range translational and/or rotational order even if the order is defined within crystallites or domains in which there is no order between the crystallites or domains. For example, a crystalline powder has long range order as does an unoriented smectic liquid crystalline material. If the range of order approaches one unit cell, short and long range order cannot be distinguished but become identical in this limit.
Diffraction of X-rays from a material possessing short range translational order consists of broad halos of scattering which cannot be indexed on a regular reciprocal lattice. Materials with long range translational order exhibit broad or sharp diffraction depending upon the range of order, but in this case the scattering cannot be indexed on a regular reciprocal lattice in at least one direction.
Amorphous polymers display short range order and may be aligned so that there is preferred orientation. X-ray scattering from oriented amorphous materials show halos of scattering which are confined to arcs but cannot be indexed on a regular reciprocal lattice.
Certain liquid crystalline materials such as nematic liquid crystals or nematic liquid crystalline polymers also scatter X-rays into broad halos which do not occur along a regular lattice. These materials may be oriented or unoriented. Amorphous polymers may be distinguished from these liquid crystalline materials by their thermal behavior. Liquid crystalline materials display first or second order thermal phase transitions upon heating which may be observed by calorimetry.
Amorphous polymers do not display thermal phase transitions upon heating, but instead display a glass transition which may be observed by calorimetry.
In another embodiment this invention provides a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR4## where PV is a main chain polyvinyl unit; S' is a pendant spacer group having a linear chain length of between about 2-12 atoms; X is an electron-donating group; Y is ##STR5## and Z is an electron withdrawing group; and the polymer has a glass transition temperature in the range between about 40.degree.-250.degree. C.
The polymer corresponding to the above represented formula can be a homopolymer or a copolymer.
The recurring PV monomer unit in the above formula can be a polymerized radical of vinyl compounds such as acrylate, vinyl carboxylate, substituted arylvinyl, and the like. When the invention polymer is a copolymer type, the PV monomer unit in the above formula is copolymerized with one or more vinyl monomers such as acrylate, vinyl halide, vinyl carboxylate, alkene, alkadiene, arylvinyl, and the like. The monomer species are exemplified by methacrylate, vinyl chloride, vinyl acetate, ethylene, propylene, isobutylene, 1-butene, isoprene, styrene, and the like.
In another embodiment this invention provides a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR6## where m and m.sup.1 are integers which total at least 10; R is hydrogen or a C.sub.1 -C.sub.4 alkyl; n is an integer having a value of 2-8; X is oxygen, sulfur or an amino or cycloamino group; R.sup.2 is a C.sub.1 -C.sub.12 alkyl or cycloalkyl group; Y is ##STR7## and Z is an electron-withdrawing group; and the polymer has a glass transition temperature in the range between about 50.degree.-200.degree. C.
Illustrative of C.sub.1 -C.sub.4 alkyl, amino, cycloamino, C.sub.1 -C.sub.12 alkyl and cycloalkyl groups are methyl, ethyl, propyl, butyl, 2-butyl, pentyl, octyl, decyl, --NH--, --NR--, ##STR8## cyclopentyl, cyclohexyl, and the like.
In a preferred embodiment this invention provides a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR9## where m and m.sup.1 are integers which total at least 10; R is hydrogen or C.sub.1 -C.sub.4 alkyl; L is --NR.sup.1 -- or ##STR10## R.sup.1 is hydrogen or a C.sub.1 -C.sub.4 alkyl group; Q is nitrogen or a --CH-- radical; R.sup.2 is a C.sub.1 -C.sub.12 alkyl or cycloalkyl group; the m monomer comprises between about 30-70 mole percent of the total monomers; and the polymer has a glass transition temperature in the range between about 50.degree.-200.degree. C.
In another embodiment this invention provides a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR11## where CP is a main chain condensation polymer unit; and S', X, Y and Z are a previously defined.
In another embodiment this invention provides a thin film optical waveguide medium comprising amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; wherein the polymer is characterized by recurring monomeric units corresponding to the formula: ##STR12## where PS is a main chain polysiloxane unit; and S', X, Y and Z are as previously defined.
Illustrative of a polysiloxane is a structure characterized by recurring monomeric units corresponding to the formula: ##STR13## where R is a C.sub.1 -C.sub.10 hydrocarbyl substituent; and S', X, Y and Z are as previously defined. Illustrative of hydrocarbyl groups are methyl, cyclohexyl and phenyl.
A present invention thin film optical waveguiding medium of an amorphous polymer has particular advantage in comparison with a medium of a liquid crystalline polymer. A present invention optical medium exhibits exceptional optical transparency, while a liquid crystalline medium exhibits a light scattering effect because of deviation from ideal crystalline order. The efficiency of light transmission in an optical waveguide is diminished by light scattering.
In another embodiment this invention provides a waveguide medium for optical modulation of light which comprises:
a. a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter; and
b. an upper cladding layer and a lower cladding layer, each of which consists of a transparent organic medium which has a lower index of refraction than the waveguiding thin film component.
In another embodiment this invention provides a thin film waveguide electrooptic light modulator which consists of a laminated assembly of substrates comprising:
a. a thin film optical waveguide medium comprising an amorphous polymer which exhibits a second order nonlinear optical susceptibility .chi..sup.(2) of at least about 1.times.10.sup.-8 esu as measured at 1.34 .mu.m excitation wavelength, and exhibits a light transmission optical loss of less than about one decibel per centimeter;
b. upper and lower cladding layers, each of which consists of an amorphous polymer medium which has an index of refraction between about 0.001-0.2 lower than the waveguiding thim film component, and which exhibits second order nonlinear optical susceptibility .chi..sup.(2) ; and
c. electrodes which are positioned to apply an electric field to the assembly of waveguiding thin film and cladding layers.
For many applications a thin film waveguide has a single mode channel structure, such as a two channel directional coupling configuration.
For some device applications it is highly preferred that an invention waveguide medium has a spatial periodic structure for phase matching of propagating fundamental and harmonic light waves. The coherence length l.sub.c of the periodic polymeric medium is defined by the equation: ##EQU1## where .DELTA..beta. is the propagation constant difference which is equal to .beta..sub.o (2.omega..sub.1)-2.beta..sub.o (.omega..sub.1). .omega..sub.1 is the fundamental frequency, and subscript zero denotes the zero-ordered mode in the waveguide. The periodic structure can be bidirectional in the form of alternating zones of uniaxially aligned polymer chains, with the alternating zones having opposite directional alignments.
An optical device containing a present invention thin film waveguide medium as a nonlinear optical component can be a laser frequency converter, an optical interferometric waveguide gate, a wide-band electrooptical guided wave analog-to-digital converter, an optical parametric device, and the like, as described in U.S. Pat. No. 4,775,215.
The theory of nonlinear harmonic generation by frequency modulation of coherent light is elaborated by A. F. Garito et al in Chapter 1, "Molecular Optics:Nonlinear Optical Properties Of Organic And Polymeric Crystals"; ACS Symposium Series 233 (1983).
As it is apparent from the foregoing description of the present invention thin film waveguide and device embodiments, an essential aspect of the present invention is the utilization of an amorphous polymer as the thin film waveguiding nonlinear optical medium, to the exclusion of liquid crystalline polymers which can be less efficient for the transmission of propagating light waves.
With respect to side chain polymers and copolymers for fabrication of thin film optical waveguide media, it is necessary to distinguish and select between closely related polymeric structures. As determined by steric effects, some side chain polymers and copolymers are amorphous and some are liquid crystalline in properties.
These factors are illustrated by the following observations in connection with the relationship between polymer structure and optical properties. ##STR14##
When n in formula I is 12, Differential Scanning Colorimetry (DSC) indicates a T.sub.g of 23.degree. C., a liquid crystalline melt phase, and a clearing temperature of 79.degree. C.
When n in formula I is 6, DSC indicates a T.sub.g of 45.degree. C., a liquid crystalline melt phase, and a clearing temperature of 67.degree. C.
When n in formula I is 3, DSC indicates a T.sub.g of 86.degree. C., and no liquid crystalline melt phase is evident. ##STR15##
The formula II homopolymer has a T.sub.g of 68.degree. C., a liquid crystalline melt phase, and a clearing temperature of 146.degree. C.
The formula III copolymer has a T.sub.g of 65.degree. C., and no liquid crystalline melt phase is evident.
The formulas II-III demonstrate that a side chain homopolymer which exhibits liquid crystalline properties can be transformed into a copolymer which does not exhibit liquid crystalline properties. The homopolymer of formula II as a thin film waveguide medium exhibits a light transmission optical loss of greater than about one decibel per centimeter, and therefore is not suitable for purposes of the present invention. The copolymer of formula II as a thin film waveguide medium exhibits a light transmission optical loss of less than about one decibel per centimeter, and therefore is a qualified optical optical medium within the scope of the present invention embodiments since it also exhibits a second order nonlinear optical susceptibility of greater than 1.times.10.sup.-8 esu when in a poled solid state.
The following examples are further illustrative of the present invention. The specific ingredients of polymer synthesis and the waveguide component fabrication are presented as being typical, and various modifications can be derived in view of the foregoing disclosure within the scope of the invention.
US Referenced Citations (12)
Continuation in Parts (1)
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915179 |
Oct 1986 |
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Patent Grant
5002361
