A high -μβ chromophore APII utilizing isophorone as π-conjugation bridge was processed into both PMMA guest host and crosslinked (XL) polyurethane network with various loading densities. High electro -optic coefficients, r33 = 30 pm/V (in PMMA) and r33 = 32 pm/V (in polyurethane) at 1.06 μm were obtained. Alignment temporal stability ranged from 90 to 120°C for XL polymer network. There is virtually no intrinsic absorption loss at 1.3 μm (solution measurement). Also noteworthy is that high optimum loading densities of this chromophore are attainable in both cases without detectable chromophore aggregation due to intermolecular electrostatic interactions.

Initial experiments of a passive polymeric TE-to-TM polarization converter that utilizes laterally offset upper and lower poling electrodes to induce a 45° optical axis in the core of a nonlinear optical polymer waveguide are reported. By optimizing the device length, we have demonstrated polarization conversion efficiencies greater than 95% in devices as short as 240 um with negligible insertion loss.

The synthesis and characterization of donor-acceptor substituted unsymmetrical bisdithiolene nickel complexes are described for the first time. X-ray single crystal data indicate that the complexes exist with two types of bonding structures, namely, the π-localized and π-delocalized structures. The relation between bonding structures and the molecular second-order nonlinear optical properties, i.e., solvatochromism, dipole moment, and molecular first hyperpolarizability is discussed.

A Holstein model is introduced for PTCDA stacks forming a one-dimensional exciton system and analyzed using Merrifield's variational method. The bandwidth and hopping integral V = 0.15 eV are obtained by comparing the absorption, emission, and fluorescence excitation of PTCDA films to solution spectra.

Modal Dispersion Phase Matching appears to be currently much better adapted to parametric mixing in polymeric material waveguides than Quasi Phase Matching. For second harmonic generation at telecommunication wavelengths, using organic materials should allow better performance than with ferroelectric crystals. Promising results are expected in view of theoretical expectations and continuously improving experimental past and current results.

Electro-optic (E-O) polymers have drawn great interest in recent years because of their potential applications in photonics devices such as high speed modulators and switches, optical data storage and information processing1–2. In order to have suitable materials for device fabrication, it is essential to design and develop polymeric material systems (active and passive polymers) with matched refractive indices, large E-O coefficients, good temporal and photochemical stability3–8 The E-O response of an active polymer commonly arises from the electric field induced alignment of its second-order nonlinear optical (NLO) chromophore, either doped as a guest/host system or covalently bonded as a side-chain. Because of the strong interaction among the electric dipoles, the poled structure is in a meta-stable state; the poled NLO chromophores which possess large dipole moment will tend to relax back to the randomly oriented state. As a result, the stability of the poled structure strongly depends on the rigidity of the overall material system. As it might be expected, the continuous increases of the rigidity and Tg of poled polymers imposes constraints on the selection of suitable chromophores that can survive the hightemperature poling and processing conditions. To circumvent this problem, we have developed a series of chromophores that possess conformation-locked geometry and perfluoro-dicyanovinylsubstituted electron-accepting group which demonstrate both good thermal stabilty and nonlinearity. This paper provides a brief review of these highly efficient and thermally stable chromophores and polymers for device applications.

In general, polymers possessing non-resonant electro-optic activities exceeding 20 pm/V require chromophores with strong electron withdrawing groups (cyanovinyls, carbon acid moieties, etc.) as well as highly polarizable bridges. Although much progress has been made on designing and preparing materials with molecular “electrooptic” activities, their incorporation into polymers to show comparably large bulk electro-optic activities has been met with little success. We report here the mature of the difficulty of the translation of microscopic to macroscopic electro-optic activity. The optimization of molecular activity increases intermolecular electrostatic interactions between chromophores, and these interactions impede induction of polar acentric order in the polymers. Theoretical analysis of the problem is presented, as well as one example of a material that is designed to circumvent these interactions. The resulting material possesses electro-optic coefficients as high as 29 pm/V and optical losses as low as 1.5 dB/cm.

We report on a spectroscopical study of a novel class of push-pull molecules containing a Chromium or Tungsten atom connected to an oligothiophene through a carbenic bond. The electronic coupling between the π electrons of the conjugated system and the π electrons of the transition metal has been monitored through absorption and Raman spectra.

This interaction between d and π electrons leads to a red shift of the thienylene π-π* absorption band and to the appearance of a new strong metal to ligand charge transfer band at lower energies. In this latter transition the electrical dipole reverses its direction upon photoexcitation from the ground to the first excited state, thus accounting for the enhanced non linear optical response of these molecules. Solvatochromic effect has been used to estimate the second order molecular hyperpolarizability.

Molecules exhibiting strong two-photon absorption hold great potential for a wide range of applications including two-photon fluorescence imaging, three-dimensional (3D) optical data storage, and 3D microfabrication. We have observed two-photon absorptivities as high as 1500×10− 50 cm4 s/photon in bis-donor diphenylpolyene derivatives that are correlated to simultaneous charge transfer from the end groups to the polyene bridge in the molecule. Many of these molecules are also excellent photoexcitable electron donors that can initiate charge-transfer reactions with acrylate monomers. Marcus theory is used to describe the efficiency of these charge-transfer reactions. Polymerization rates have also been measured and we show that these twophoton chromophores display increased sensitivity and recording speed over conventional UV photo-initiators. The fabrication of complex, three-dimensional structures by twophoton polymerization is demonstrated and discussed in the context of advanced photonic applications.

Nanoscale synthesis and processing provides a novel approach for making a new generation of nanocomposite materials with exceptional optical and electrical properties that are needed for the development of new technologies. This presentation will focus on the preparation of nanocomposites made of Poly (para-phenylene vinylene) (PPV) with other polymers, inorganic glasses and semiconductors. We will present a new approach of nanoscale polymerization for making processable monodispersed oligomeric species of PPV which uses the base catalyzed polymerization of PPV monomer within the cavity of a reverse micelle nanoreactor. Application of this approach of fabricating novel materials for a variety of applications in photonics will also be discussed. In addition, we will discuss fabrication of bulk nanocomposites of PPV and silica by insitu polymerization of monomer within a porous glass and their lasing properties.

We review our results from spectral studies of the ultrafast excited-state absorption in fullerenes and derivatized fullerenes. These results allow determination of both the spectral response of reverse saturable absorption (RSA) nonlinearities such as optical limiting (OL) in fullerenes, and the dynamical response for different morphologies. We have investigated the effects of thin film and various sol-gel glass environments on the nanosecond OL and femtosecond dynamics of derivatized fullerenes. These data provide evidence of decay pathways which compete with the intersystem crossing to a triplet from the initial singlet states. With appropriate processing, however, the OL response of derivatized-fullerene sol-gel glasses can be enhanced to approach that of the same molecule in solution, while significantly enhancing the optical damage threshold. The optical limiting of these derivatized fullerenes is compared with that of various porphyrin and phthalocyanine molecules.

A series of conjugated donor-acceptor trienes in which the central double bond is incorporated into an unsaturated isophorone, verbenone or chromone ring has been synthesized. In each case, the donor group consists of an amine and an aromatic or heterocyclic ring system, and the acceptor is the dicyanomethylidene group. The nonlinear optical properties of each of the compounds has been measured and correlated with its structure. The dipole moments and molecular hyperpolarizabilities of these compounds, like those of other conjugated polyenes, are large enough to be used as the active components of electro-optic polymers. Unlike other donor-acceptor polyenes, however, these compounds exhibit the thermal stability required for such applications.

To fill the gap between molecular design and the architecture of three-dimensional functional structures, we propose novel hyper-structured molecules (HSMs) based on welldefined and topologically controlled molecular systems. To this end we have developed carbazole dendrimers, trimers, cyclic oligomers and chromogenic calix[4]arenes as HSMs. Photorefractivity was selected as the primary target function of these HSMs. Oligomers developed in our laboratory exhibit intrinsic photocarrier generation, transport, electro-optic, film-forming and poling properties. These multifunctional properties allow us to demonstrate optical image processing using optical phase conjugation. The topological shapes of indoaniline-derived calix[4]arenes were studied by hyper-Rayleigh scattering. The two indoaniline moieties in calix[4]arene derivatives were pre-aligned so as to enhance the net molecular hyperpolarizability. Besides dendric oligomers, cyclic oligomers can be used as a molecular platform which allows molecular level tuning of shape, size and topology for superior opto-electronic functions.

We wish to report the synthesis of a new class of peripherally modified, polyphenylated phthalocyanines (Pcs) and metallophthalocyanines (MPcs). These compounds were synthesized by cyclic tetramerization of functionalized pentaphenylbenzophthalonitriles. The phthalonitriles were made in several steps via Diels-Alder cycloaddition between phenylethynylphthalonitrile and substituted tetracyclones. The polyphenylated design leads to enhanced solubility. Thin films can be cast from solutions of the butoxy and dodecaoxy substituted polyphenylated Pcs and MPcs. Cyclodehydrogenation of the Pcs was studied in an attempt to produce planar systems. Preliminary results indicate the pentaphenyl substituent is too bulky to planarize under the conditions employed.

A series of polybenzonitrile derivatives, prepared by plasma glow discharge processes or chemical polymerization, were characterized by FT-IR, UV-Vis, GPC and VPO etc. The secondorder nonlinear optical hyperpolarizability γ of various benzonitrile monomers and their, polymers were measured by the femtosecond time-resolved optical Kerr effect technique, and the structureproperty relationships were discussed. The power law dependence of γ on the averagepolymerization- degree of several polybenzonitrile derivatives were also reported.

Spontaneous emission from exciton states in an aggregate of π-conjugated oligomers is studied theoretically. Each oligomer is taken as a ring of N carbon atoms and is treated using a PPP Hamiltonian. Coulombic interactions between rings are treated to first order. The radiative decay rate γ from an exciton state in an aggregate of M aligned oligomers is superradiant, being M times faster than the decay rate of an isolated oligomer exciton. Inter-oligomer interactions have little effect on the exciton size and energy when the oligomer size N is large compared to the interoligomer spacing. However, when N is small, both the exciton size and energy are strongly affected by these interactions, leading to a markedly different N dependence for γ.

A series of bis-(diphenylamino)diphenylpolyenes containing up to eight double bonds has been synthesized, both as parent model compounds, and functionalized for attachment as pendant chromophores. Oxidative doping of these new materials yields exceptionally stable bipolaronlike dications, even at the triene level. These new materials show promise as bimechanistic optical limiters by reverse saturable absorption and by 2-photon absorption.

In this contribution, we investigate by means of correlated quantum-chemical calculations the influence of intermolecular interactions on the absorption and emission properties of conjugated chains. Various strategies are suggested to avoid a substantial decrease in fluorescence quantum yield in condensed media. Finally, the reliability of our theoretical approach is validated by showing the remarkable agreement obtained between the experimental data and the calculated optical properties of clusters formed by sexithienyl molecules.

A new emulsion process has been developed for the direct synthesis of the emeraldine salt of polyaniline (PANI) that is soluble in organic solvents. The process entails forming an emulsion composed of water, a water soluble organic solvent (e.g., 2-butoxyethanol), a water insoluble organic acid (e.g., dinonylnaphthalene sulfonic acid) and aniline. Aniline is protonated by the organic acid to form a salt which partitions into the organic phase. As oxidant (ammonium peroxydisulfate) is added, PANI salt forms in the organic phase and remains soluble. As the reaction proceeds, the reaction mixture changes from an emulsion to a two phase system, the soluble PANI remaining in the organic phase. With dinonylnaphthalene sulfonic acid (DNNSA) as the organic acid, the resulting product is truly soluble in organic solvents such as xylene and toluene(not a dispersion), of high molecular weight (Mw >22,000), film forming and miscible with many polymers such as polyurethanes, epoxies and phenoxy resins. As cast, the polyaniline film is only moderately conductive, (10−5 S/cm), however treatment of the film with surfactants such as benzyltriethylammonium chloride (BTEAC) or low molecular weight alcohols and ketones such as methanol and acetone increases the conductivity 2–3 orders of magnitude.

Conjugated polymers with narrow band gap are promising candidates for symmetric electrochemical devices, such as electrochromics and redox supercapacitors, which involve the pand n-doped state of the polymer. Polydithienothiophene materials which are prepared from isomer monomers show this characteristic. The copolymerisation of two dithienothiophene isomers leads to materials whose electronic properties depend on the monomer ratio. Optical and electrochemical characterizations of different copolymers are reported and discussed.