We have investigated the effect of solvent polarity on the conformations of two zwitterions. A Nuclear Magnetic Resonance (NMR) study shows that changing the solvent results in large intramolecular charge transfer. However NMR measurements indicated that a benzenoid ring structure predominates the ground state structure for both zwitterions in polar and non polar solvents. In spite of their very different solvatochromic behaviors, both compounds present a sharp enhancement of the quadratic hyperpolarizability on increasing the solvent polarity.

We report the synthesis and evaluation of new highly polar molecules whose combined non- linear and linear optical properties are of interest for frequency doubling. The generic scheme for the syntheses rests on enamine substitutions of tetracyano-p-quinodimethane (TCNQ). In the case detailed, a novel reaction product is reported from the unexpected reaction of triethylamine and TCNQ. In polar solvents such as DMF, the molecule has a charge separated ground state and a measured bipole moment of 45 D. Also in polar solvents, the value for the resonant (beta) coefficient is measured to be -190 X 10^-30 esu. Coupled with acceptable transparency at 460 nm ((epsilon) equals 86 M^-1 cm^-1) this molecule points to a new approach in the design of such materials.

Recently, substantial progress has been made in molecular design of nonlinear optical chromophores toward the goal of large nonlinearities while retaining thermal stability. Modifications of donor groups, delocalized (pi) -systems, and acceptor groups have all been made, and examples of each are described. The utility of each modification for preparation of electro-optic polymers is discussed. Resistance to thermal decomposition is not sufficient for practical applications; NLO polymers must also be resistant to thermal depoling and to sublimation of chromophores out of the polymers. It is therefore concluded that chemical tethering is required. Synthetic strategies for tethering our better chromophores to thermally stable polyimides are described, and the results of materials prepared to date are given.

Electrooptical and electromechanical effects of a PNA substituted rigid rod-like polymer have been studied experimentally. Modulated attenuated reflection spectra show a strong piezoelectric contribution to the overall field induced response. The piezoelectric coefficient d^P as determined independently by a Nomarski interferometer was found to be comparable in size to the electronic electrooptical coefficient (chi) ⁽²)_zzz. This behavior is explained by the particular electronic configuration of the PNA chromophores.

We have developed two classes of highly efficient and thermally stable nonlinear optical chromophores using fused-thiophene and bithiophene as conjugating units. Experimental studies indicate that the use of fused-thiophene or bithiophene as a (pi) conjugating bridge provides an excellent tradeoff between nonlinearity and thermal stability. In addition to the chromophore developments, we have employed new synthetic methodologies to obtain thermally stable poled polyimides.

We propose a novel type of chromophore, naphthoquinone methide dyes, for nonlinear optics used in the near IR wavelength. The large resonance effect and the small intermolecular interaction allows the chromophore to show a large Pockels coefficient at 1.3 micrometers when it is poled in a polymer matrix. The origin of the nonlinearity is discussed by measuring the ground state dipole moment and the change in dipole moment between the ground and excited states. The polyurethane to which this dye was chemically attached was synthesized and the large nonlinearity was demonstrated. In polymer films, propagation loss at 1.3 micrometers increases maybe due to the aggregation of chromophores.

We report our study of a new sol-gel polymer for nonlinear optics applications. An amino- sulfone dye chromophore was covalently incorporated into a sol-gel network and each chromophore was firmly anchored at both ends via nine possible crosslinking sites. After corona poling and thermal curing at elevated temperatures using a new kind of `step' poling profile, a d<sub>33</sub> of 27 pm/V was measured at the 1.06 micrometers fundamental wavelength. Long term stability at 100 degree(s)C and short term stability at 200 degree(s)C were demonstrated. A phenomenological explanation for the behavior of the dynamic SHG signal to our `step' profile is also proposed.

Significant asymmetry and optical nonlinearity (second harmonic generation) can be produced by injection of electric charge into dye/polymer blends. The mechanism for producing the nonlinearity is different from the usual dipolar alignment of the dye in an electrostatic field. Charge injection has been achieved by purely electrical means using `in-plane' electrodes, or photochemically, by irradiating a bilayer structure comprising a photoconductive layer and the polymer/dye layer. This latter technique allows spatial modulation by light of nonlinear optical coefficients.

Nonlinear optical properties of 3, 4, 9, 10-perylenetetracarboxylic dianhydride thin films grown by ultra-high vacuum process of organic molecular beam deposition are characterized by self-diffraction method. We observe a large diffraction efficiency (approximately 10^-4) from a micron thick film and attribute the nonlinearity to a thermal shift in the excitonic absorption feature or free carrier effects.

We describe a new method for poling polymers containing nonlinear chromophores. It consists in taking advantage of the polar character of the coherent superposition of a laser beam and second harmonic. Though the resulting electromagnetic field averages to zero, its odd harmonics do not. This offers the possibility of a polar selective excitation of nonlinear chromophores via the interference between one- and two-photon absorption. Experiments were performed on thin films of disperse-red1 dissolved or chemically attached to a PMMA matrix, using a Nd-YAG laser at 1064 nm and its second harmonic obtained after frequency doubling in a KDP crystal. The resulting electro-optic coefficients are comparable to the values obtained by the usual dc-field poling. We have also determined the linear [(chi) ⁽²)(-(omega) ;(omega) ,0)] and quadratic ](chi) ⁽³)(-(omega) ;(omega) ,0,0)] electro-optic coefficients wavelength dispersion in corona-poled thin films, using the modulated ellipsometry technique. One advantage of this technique is the possibility to perform measurements inside the absorption band. From the obtained values, it was possible to determine microscopic parameters of the chromophores such as the dipole moment difference between fundamental and excited states. A resonance of the (chi) ⁽²) dispersion is observed, red-shifted with respect to the one- photon transition.

Four high T_g side chain polymers have been investigated based on polyimide and acrylate backbones functionalized with DR1 and heterocyclic thiophene chromophores. UV-VIS studies revealed chromophore stability up to 210 degree(s)C. Maximum poling efficiency was found approximately 15 K above T_g. From dielectric relaxation studies and from poling dynamics it is obvious that chromophore reorientation follows an Arrhenius law at temperatures well above T_g leading into a WLF-behavior in the vicinity of T_g. Relaxation of the EO-coefficient could be interpreted in terms of a KWW function. The average relaxation times strongly deviate from the WLF-function at temperatures well below T_g and can be described with an Arrhenius law. Activation energies here are significantly smaller than those in the high temperature limit above T_g, indicating that the chromophore dipoles are incompletely coupled to the polymer (alpha) process. Very good stability was observed for the polyimide P3 with average relaxation times of 10⁴ years at 50 degree(s)C and 4 months at 120 degree(s)C. EO coefficients of up to 12 pm/V at 1541 nm were realized using a poling field strength of 1 MV/cm. EO-coefficient at constant poling field was found to be approximately linearly dependent on chromophore content. Channeled waveguides were fabricated by selective reactive ion etching with small losses of 1 dB/cm at 1318 nm. However, loss varies strongly between 1 dB/cm and 3 dB/cm depending on film quality.

This paper describes some poled electrooptic bulk polymers (EOP) of the guest/host type having a cured epoxy resin as the host. The electrooptic polymers of typical dimensions 13 X 13 X 3 mm are characterized with respect to application as Pockels materials in an optical high voltage sensor. The electrooptic coefficients obtained here are of the same order of magnitude as those which are required for high voltage applications. An optical sensor based on disperse red 1 dye and an epoxy polymer is developed. It is able to measure voltages up to 10 kV AC. It is shown that bulk EOP can be produced with relatively large physical dimensions comparable to commercially available Pockels crystals. A technique is described which compensates for the inevitable intrinsic birefringence built into most bulk polymers. The epoxy based EOP shows high orientational stability, even when compared with a polysulfone based EOP having a higher glass transition temperature.

We report on the demonstration of a fast photomechanical effect where a 5 ns laser pulse induces a length change in a polymer optical fiber that displaces an 8 gm mass by about 5 nm. Two equally dominant mechanisms appear to be responsible: a fast response that follows the 5 ns laser pulse and a slower response that decays with a 12 ns time constant. Accelerations of at least 6 X 10⁸ m/s² are observed. These effects are modeled with an electrostrictive mechanism. The calculated length change is consistent with the measured value.

A simple and easy method to study the dispersion of electro-optic coefficients of poled second- order nonlinear optical polymer films is presented. Phase grating type electro-optic modulators were used to measure the relative electro-optic effects at different wavelengths. The grating structures were formed by either etching a grating in the nonlinear polymer thin films or defining a transparent electrode on top of a uniform polymer film. When an AC voltage is applied to the electrodes, the diffraction efficiency of the grating is modulated by the small index modulation. The measurement of the electro-optic response can be carried over a large wavelength range, even deep into the absorption band of the material due to the short interaction length of the optical beam and the polymer thin film. The grating modulation method uses a single optical beam in a transmission arrangement which requires little optical alignment and no polarization optics. With a properly designed electrode, the grating modulator can also be used in measuring the electro-optic coefficient, r₁₃, of the poled polymer films. Other measurement applications such as monitoring temporal, thermal, and photo-excitation stability are discussed.

A mathematical model of the bulk photovoltaic effect in polyvinylidene fluoride (PVF₂) films due to the optical excitation of impurities or defects in an asymmetric potential is developed. The asymmetry is due to the internal electric field of a poled PVF₂ thin film. This effect gives rise to a photocurrent in the absence of an applied electric field in contrast to the conventional photovoltaic effect in ordinary semiconductors. A space charge formation mechanism, based on the non-equilibrium carriers and some characterizing parameters of the traps in the band gap, is modelled. According to this approach the photovoltaic effect is described by three nonlinear interactive differential equations. The equations are solved both analytically and numerically and closed-form formulae for the photovoltaic current and voltage are derived. A computer simulation for the phenomena is performed using the developed model. The results of simulation agree within acceptable accuracy to the experimental results.

A special class of thermally stable poly(arylene ether) phosphine oxide polymers is being investigated for second-order nonlinear optical applications because of their high glass transition temperatures (> 200 degree(s)C). These polymers also have strong hydrogen bonding sites that can interact with the chromophores which may improve the temporal stability of chromophore orientation following poling. This work describes the polymer physics including structure/property relationships; in particular, the chromophore/polymer interactions and polymer backbone structures that influence the thermal and temporal stability of chromophore orientation in these polymer matrices. Second harmonic generation is sensitive to local changes in the polymer microenvironment and thus is an excellent technique for probing chromophore orientational dynamics during and following poling and the effect of dopant/polymer interactions on the temporal stability. Dielectric relaxation is employed to examine the intermolecular cooperativity and segmental relaxation behavior arising from different polymer backbone structures and steric effects. It is critical to understand how structure/property relationships affect the chromophore orientational dynamics and polymer relaxation in these polymers so that one can better tailor materials for nonlinear optical device applications.

We report on the results of studies of photorefractive properties of a multicomponent polymer composite of PVK-TCP:C₆₀:DEANST. Efficient plasticization of the host polymeric matrix with the TCP agent and utilization of a nonlinear chromophore with large dipole moment allow for achieving large poling-induced electro-optic coefficient. Diffraction efficiencies exceeding 40% and stationary nonreciprocal net two-beam coupling gain coefficients in excess of 100 cm^-1, surpassing those of known inorganic single- crystalline photorefractive media, are reported. Dependency of the kinetics of photorefractivity in the composite on external electric field and writing beams fluencies is discussed. An example of holographic recording and retrieval of an image of the standard USAF optical resolution target is also demonstrated.

We present the photorefractive properties of a new organic composite operating at near IR wavelengths. The composite contains an ionic thiapyrylium dye, 4-(4-dimethylaminophenyl)- 2,6-diphenyl thiapyrylium perchlorate as a photocharge generation sensitizer, 4-(N,N- diethylamino)-((beta) )-nitrostyrene as a second order nonlinear optical chromophore, and poly(9-vinylcarbazole) as a host polymer which also serves as a charge transporting agent. Both degenerate and nondegenerate four-wave mixing experiments have been carried out and holographic diffraction efficiencies as high as 2% have been achieved. Asymmetric energy transfer has been observed with a gain of 7 cm^-1 in a two-beam coupling experiment. This paper focuses on the dynamics of the formation and erasure processes of the holographic gratings. Both the writing and erasure times exhibit sublinear dependencies on the illumination power intensity, which is a result of the sublinear photoconductivity of the material. The dependence of the rise time on the applied electric field is attributed to the field dependence of both the photocharge generation quantum efficiency and the charge mobility in the polymer matrix.

We measure the magnitude and phase of the degenerate third-order nonlinear optical susceptibility (chi) ⁽³)_llll of solutions of various bis-thienyl polyenes (n-BTP) with the number n of the conjugated double bonds ranging from 3 to 9. We study both neutral and bipolaronic (i.e., doubly ionized) forms of n-BTP. We find that, within experimental error, (chi) ⁽³)_llll is proportional to n^b where b-5.5 at 532 nm for our neutral n-BTP samples which have 3 <EQ n <EQ 9, and b-14 at 1.06 micrometers for the bipolaron state samples which have 6 <EQ n <EQ 9 where the probing laser wavelength is close to an absorption band. We calculate (chi) ⁽³)_llll of the bipolaronic n-BTP assuming it is associated with this absorption band acting as a two-level system and find good agreement with experiment.

A phase-conjugate interferometer, based on degenerate four-wave mixing in the retroreflected pump beam configuration, is used to determine the complex third-order hyperpolarizability of organic molecules in solution. The imaginary part of this third-order hyperpolarizability yields a value for the two-photon extinction coefficient of the molecule. This is an absolute value with respect to the reference material and does not depend on the laser intensity used. We show that the observed attenuation in the phase-conjugate signal is not necessarily due to two- photon absorption. In several cases more complex loss mechanisms are responsible for the absorption of the signal.

A new class of photorefractive polymers is described in which an inert polymer binder is doped with a great molecule called a dual-function dopant, which has the dual functions of providing optical nonlinearity as well as charge transport as required for the photorefractive effect. These materials are the first photorefractive polymers to show both nondestructive readout as sufficiently low reading power and optical trap activation, in which pre-irradiation by a uniform light beam increases the concentration of deep trapping sites in the material. In the area of potential applications, a new sample configuration is described in which photorefractive polymers are fabricated into an electric field switchable stratified volume holographic structure. Individual layers may be activated by applied electric field leading to improved diffraction efficiency and angular selectivity.

Location of optical charge pairs formation in (alpha) -sexithienyl thin films has been determined by absorption and electroabsorption measurements carried out at 300 K and 4 K. The polarizabilities of the excited Frenkel exciton states have also been estimated. The exciton binding energy is in the order of 0.4 eV.

The molecular hyperpolarizabilities (gamma) of several soluble organometallic compounds have been determined by third-harmonic generation in solution at 1.064 and 1.907 micrometers fundamental wavelengths. Both, the real and imaginary parts of (gamma) have been determined from the concentration dependence of the harmonic intensity. Values between 10^-33 and 10^-32 esu have been found, depending on excitation wavelength and metal substitution. Results have been discussed with reference to those recently measured by us for metal-free (H₂Pc) and copper (CuPc) phthalocyanines. Quantitative analysis have been carried out, based on four-level model expressions for the dispersion of (gamma) . Experimental values have been described in terms of two excited one-photon allowed levels (corresponding to transitions associated with bands observed in the linear optical spectrum at around 0.3 and 0.9 micrometers ) and a one-photon forbidden (two photon allowed) level placed between both transitions.

Fractal clusters are known to act as electric field enhancers at the microscopic level. The inclusion of such clusters within a nonlinear material can greatly magnify the nonlinearity of the material. We have theoretically investigated the role an electrostrictive response, in an electrooptic type of measurement, where the index of refraction is altered by the electric field induced deformations of the spherical metal inclusions and how the surface plasmon resonance plays a role in the magnitude of the nonlinearity. We report on the fabrication of such clusters in a PMMA host material, and how linear absorption measurements can be used to probe the formation of metal particles and the aggregation of the particles into a cluster.

Second harmonic generation and UV-visible spectroscopic measurements have been performed on a series of Z-type Langmuir-Blodgett monolayer of indodicarbocyanine, hemicyanine and stilbazium salts. Optical spectra of these monolayer indicate the presence of hypsochromically shifted aggregates on the silica surface. The extent of aggregation is found to be largely dependent on the nature of the counter-ion as well as on the conditions of the monolayer preparation. The SHG intensity of dye aggregates are much smaller compared to that of monomeric dye molecules. In the case of amphiphillic counter-ion containing stilbazium salt compression speed of the monolayer has very little effect on the second harmonic signal and on the absorption spectrum, presumably due to the suppression of aggregation. It seems that the contribution from nonlinear optically active amphiphillic counter-ion to the SHG intensity is not that significant.

Third-order nonlinear optical (NLO) properties of quinoid dyes were studied by third harmonic generation measurement. A large (chi) ⁽³)(-3(omega) ;(omega) ,(omega) ,(omega) ) value of 4.8 X 10^-11 esu was found on 2,6-di(n-butylamino)-4,8-dihydroxy-1,5-naphthoquinone and contribution of the `Molecular Strip' through intermolecular hydrogen bonds to the large NLO property was suggested from crystal structure analysis. According to the suggestion, we evaluated (chi) <sup>(3</sup>)(-3(omega) ;(omega) ,(omega) ,(omega) ) values 1,4- dithioketo-3,6-diphenyl-pyrrolo-[3,4-c]-pyrrole, which also form the `Molecular Strip', to be 1.7 X 10^-11 esu.

Introducing a chirping structure into a periodic nonlinear optical (NLO) susceptibility (chi) ⁽²) in a slad-waveguide, enhanced second-harmonic generation (SHG) has been preliminarily demonstrated in the Cerenkov-radiative scheme. Since this chirped periodic (chi) ⁽²) structure can be general form to both uniform and periodic (chi) ⁽²) cases, the available Cerenkovian SHG powers are compared for three different NLO (chi) ⁽²) structures such as the uniform, periodic and chirped periodic schemes, based on the theoretical model of the chirped (chi) ⁽²) configuration. Some of experimental verification on the enhanced SHG power is also given with vinylidene cyanide/vinyl acetate organic copolymer in an asymmetric slab-waveguide.

An attractive and challenging approach to the construction of robust, thin film materials with large second-order optical nonlinearities is the covalent self-assembly of aligned arrays of high-(beta) molecular chromophores into multilayer superlattices. In this paper, we describe the dispersion of the large second harmonic generation (SHG) response in a self-assembled film containing stilbazolium chromophore building blocks. We also describe a new approach to fabricating SHG waveguides with such materials as well as preliminary confirmatory experimental results.

Two kinds of poled polymer systems, DR1/PMMA and p-NA/PVA were set in artfully designed frequency doubling multi-layered waveguides. (Ti₂O₅)_x/(SiO₂)_y glass which was adjustable on refractive index by varying the ratio, x/y was inserted between poled polymer nonlinear optical layer and glass substrate to optimize conversion efficiency of frequency doubling. Also a face-to-face structure of poled polymer film was applied to frequency doubling waveguide in Cerenkov-type phase matching. In this structure d₃₃:-d₃₃ counter-parallel distribution was effective for overlapping of both fields. Finally ridge-type channel waveguide was prepared for high efficiency SHG waveguide.

Second harmonic generation via counter propagating beams was demonstrated in poled polymer channel waveguides which were efficiently poled by in-plane geometry (d₂₂ equals 153 pm/V). Although applications for high speed signal processing, such as pulse convolution and wavelength division multiplexing, are our primary object, it has competitive potential for frequency doublers against normal co-propagating geometries because of utilization of large resonant nonlinearities.

We present a procedure for trivially preparing soluble, spinnable phthalocyanine plastics and elastomers containing high concentrations of silicon phthalocyanine incorporated as a copolymer. Polymers prepared by this method can easily be fashioned as thin films for optoelectronic applications. We present a visible broad band quadratic electroabsorption measurement on one such thin film, providing the real and imaginary components of (gamma) as well as the figure of merit Re[(gamma) ]/Im[(alpha) ].

A new amphiphilic compound NMOB [2-nitro-5- (N-methyl-N-decosyl) aminobenzoic acid] with both good film forming property and high optical nonlinearity was synthesized for applications of Langmuir-Blodgett films in waveguide-type second harmonic generation (SHG) devices. The near-quadratic dependence of the SHG intensity on the bilayer number, the small angle x-ray diffraction patterns and the temporal stability of alternating CdA(cadmium arachidate)/NMOB multilayers confirmed their good film structures. We obtained the hyperpolarizability (beta) of NMOB of 6.3 X 10^-50Cm³V^-2 in SI units or 1.7 X 10^-29 esu at a fundamental wavelength of 1.064 micrometers from transmitted SHG measurements which agreed with those deduced from our linear electro-optic (EO) modulated attenuated total reflection spectra at 832 nm, 633 nm and 488 nm in the order of magnitude. A resonant enhancement of the EO response near the absorption band in NMOB monolayers was observed for the first time.

There can be no commercial poled-polymer optical waveguide switches until several goals are reached. Among these are thermal stability, low switching voltage, and low-loss waveguides with acceptable fiber insertion loss. We report on two cross-linked materials; one shows r₃₃ values above 10 pm/V and retains 80% of its E-O coefficient after 1500 hours at 100 degree(s)C. Using these systems for illustration, we discuss material requirements and design tradeoffs to optimize performance.

Planar waveguides of poly-di-allyl-terephthalat (PDATP), a material with a high elasto-optic coefficient, are studied for the purpose to form active components. A special piezo quartz is embedded into a polymer matrix with the PDATP planar waveguide. By applying a voltage of 180 V a phase shift of 2(pi) is observed.

Electro-optic (EO) channel waveguide polymer phase modulators made by laser ablation are described. The ablation technique is capable of forming low loss channel waveguides at rapid rates with endface quality suitable for fiber pigtailed devices. Loss measurements as well as SEM micrographs were taken to optimize this process. Optical losses of these channel waveguides (before poling) were measured to be 0.37 dB/cm (TM mode) and 0.33 dB/cm (TE mode) at 1.32 micrometers wavelength. The polymer used as poly(methyl methacrylate) with disperse Red 1 dye attached as a side chain at a concentration of 10 mole %. In the poled channel waveguide phase modulator, an EO coefficient (r₃₃) of 10.5 pm/V was achieved with electrode poling and measured by a heterodyne detection system.

The integration of efficient semiconductor lightsources with low-loss functional optical waveguide devices is one of the major problems in integrated optics. In this paper we present a novel integration scheme based on the epitaxial lift-off technique for the integration of a laser diode array with an array of polymeric waveguides. This method shows a number of advantages with respect to previously reported solutions. The presented quasi-monolithic integration of laser diodes with polymeric waveguides might lead to important applications in areas such as optical interconnections and optical communications.

We report the electro-optic and thermal stability properties of a new class of novel thermostable fluorene-based cardo-type polymers. The electro-optic coefficients found for these materials are comparable to those obtained from many other reported side-chain polymers. Isothermal decay measurements for both the charge transfer absorption bands and for the electro-optic responses demonstrate that the thermal degradation of electro-optic response in these materials is dominated by chemical degradation and not by depoling, at least over a large range of elevated temperatures. One of these materials for example is characterized by a measured 1/e decay time of over 40 days at 190 degree(s)C with extrapolated lifetimes of over one year at 175 degree(s)C.

Polymeric optical components are potentially low cost and reliable components for applications in optical telecommunication and datacom. A number of (optically nonlinear) polymers has been used to make planar integrated optical components. Various types of passive and active polymeric guided wave devices were made in a multilayer of polymers with different refractive indices, deposited onto a substrate. Lateral confinement of the (channel) waveguides has been obtained via photobleaching applying masks containing the desired waveguide lay-out. The electro-optic effect has been induced via electric field poling. The devices thus made show switching voltages in the range 5 - 10 Volts at a wavelength of 1330 nm together with extinction ratio's in excess of 20 dB. For the passive devices, waveguide propagation losses around 0.4 dB/cm were observed; for switching devices, values were around 1 dB/cm. An important feature is the reliability and environmental stability of these polymeric devices; this issue will be discussed.

We report on a new class of devices in which laser light is used to control the length of a material. To demonstrate these devices we have designed an all-optical circuit that, using feedback, allows us to control the length of a polymer optical fiber in three ways: stabilization, discrete positioning and continuous positioning. We also report the dependence of response time on fiber length. Many mechanisms long known to result in a refractive index change also result in a length change. For our circuit we have utilized the heating mechanism to control length. While this heating mechanism is relatively slow it is also relatively large in magnitude.

Electro-optic (EO) poled polymer materials exhibit low dispersion and low dielectric constants. EO polymer materials have been modulated flat to 40 GHz and exhibit few fundamental limits for ultrafast modulation and switching. Channel waveguides and integrated optic circuits can be defined by the poling process itself, by photochemistry of the EO polymer, or by a variety of well understood micro-machining techniques. EO polymer materials have been used to fabricate high-speed Mach-Zehnder modulators, directional couplers, Fabry-Perot etalons, and even multi-tap devices. Practical issues remain to be solved before polymer photonic technology may be exploited in systems such as datacom and telecom. These include reliable, low cost fiber-attach and packaging, support circuitry and interfaces, and the scale-up to high volume production. This talk reviews requirements for practical exploitation and displays recent progress toward achieving reliable products.

An important potential application of organic materials for nonlinear optics lies in the field of optical switching and power limiting. One advantage of using polymeric suspensions is that one can chemically control the position of the absorption peaks thereby changing nonlinear properties associated with absorption. In this work we report on the nonlinear transmission characteristics of Poly(isothianaphtene) suspended in various solvents. The polymers were synthesized from Dichloro-o-xylene and polymerized with the use of several oxidizing agents. Submicronic particles were obtained by crushing and straining the polymers. We investigated the nonlinear transmission threshold its dependence on the oxidizing agents and the solvents and the mechanisms leading to the nonlinearity. Measurements were carried out at 1064 nm. In some cases nonlinear transmission thresholds were found to be comparable to that of carbon black suspensions. The absorption per particle was found to be important in determining the nonlinearity threshold. The mechanism responsible for the nonlinearity was identified as thermal in nature and is characterized by scattering, plasma formation, self action of the medium and increased absorption due to particle break up. This mechanism is close to that found in carbon-black suspensions but with some important differences that will be discussed.

The results of comparative investigation of tungsten oxides doped with organic or complex compounds are proposed. The additives sufficiently vary the structure relaxation phenomena, donors accelerate and acceptor reduce one. The change of films transition under due of variation of laser irradiation local effect are discussed. This change determined by change of film temperature in the first place. The results of experiments explained by features of electron band structures of investigated films. The data were received from nonlinear transition effects under due of focused laser radiation with density up 5(DOT)10¹⁰ W/m².

We report on second harmonic generation measurements of a polymer-impeded electric field induced rotation of the dye molecule Disperse Red 1 in a series of styrene-methyl methacrylate copolymers of varying composition. We show by analysis of a generalized hypothetical binomial or multinomial distribution, that the dye molecules are not randomly distributed through the polymer, and apparently associate more strongly with the styrene and methyl methacrylate homopolymer regions. This could also be viewed as evidence of non-random distribution of the two monomers of the copolymer.

Photorefractive (PR) polymers are a new class of PR materials in which large (approximately 10^-3) photoinduced refractive index changes can be generated with very low light power density (approximately 100 mW/cm² or less). They offer structural flexibility, ease of processing and lower cost compared with commonly used inorganic PR crystals. We have developed a PR polymer composite with significantly enhanced performance compared with the existing PR polymers: for the first time, complete diffraction of an incident beam into the first (Bragg) diffraction order was observed in a 105 micrometers thick layer of a PR polymer. Absorption and reflection losses limit the measured maximum diffraction efficiency to 86%. The material also exhibits a net two-beam coupling gain of more than 200 cm^-1. These results show that this class of materials presents a good practical alternative to the inorganic PR crystals.

UV bleaching of side-chain polymer PMMA/DR1 has been characterized at different temperatures and different UV bands. Broadband mid-UV bleaching at elevated temperature has been found to be most efficient and has been used to fabricate polymeric directional couplers. A fabricated passive directional coupler has achieved 26 dB extinction ratio in the cross state. The simulated output power ratios of various interaction lengths agreed with the measurements of the fabricated devices.