Molecular photonics, information processing based on strong interactions of photons and molecules, has attracted much attention, since it can fully utilize many superior properties of both photons and molecules. We have been developing materials showing ultrafast absorption changes in the visible to near infrared regions by photoinduced electron transfer and reverse reactions or by excited electronic state formation. Guided wave mode (GWM) geometry composed of a prism, a metal thin film, and a photoresponsive polymer film successfully achieved sensitive, all optical, and very fast control of reflectance by transient or persistent changes of GWM conditions by means of photoinduced complex refractive index changes upon nanosecond to femtosecond laser excitation. All-optical parallel control of reflected probe light by pump (writing) light was demonstrated by photochromic spiropyran or fulgide, and various metallophthalocyanines dispersed in appropriate polymers.

To date, a full-scale solar sail has never flown in space. Furthermore, solar sail technology development represents a field that only recently has enjoyed significant support. The goal of this work is to contribute to the development of a low-mass ODS for solar sails that would include research and development in the areas of photogrammetry and thermography. The focus of this work was on the development of the thermography system. A measurement protocol was designed for obtaining accurate temperature measurements using thermal imaging when heat was applied to the membrane surface. Two main limitations were considered during the experimental process. The first is that conventional infrared detector arrays must be kept cool. To minimize the effect that an imager's operating temperature would have on the ODS, a miniature, un-cooled microbolometer was used to acquire temperature measurements from the membrane surface. A second limitation is that a detector array cannot distinguish between emitted and reflected photons, thus presenting a significant problem if one cannot predict the reflected component or if the reflected component is significantly greater than the emitted. To address this limitation, spectral properties of the membrane, including reflectance and transmission, were analyzed using a Hemispherical Directional Reflectometer (HDR) to predict the effects that optical properties would have on sail membrane temperatures. A thermal modeling strategy was also developed. The results of this investigation are presented.

Light-induced optical anisotropy have been studied by laser grating inscription method within the group of novel azobenzene functionalized polymers. Undergoing light-induced trans-cis-trans photoisomerisations azo-benzene groups were covalently bonded to the main chains of polymers. Two-wave mixing technique was employed to inscribe the amplitude and phase gratings in these polymers. Using two light polarization geometries s-s an s-p we were able to study differences in grating properties as well as ability of surface relief grating formation in studied class of polymers. The supplementary technique of moving grating was used as a tool for obtaining information on contribution of various reorientations of chromophores and main chains to light diffraction on the obtained periodic structures.

The performance of optoelectronic devices can be increased by incorporating a high refractive index layer into the system. This paper describes several potential high refractive index resin candidates. Our materials include the added advantages over other systems because the new materials are cationically photocurable and free flowing, have low shrinkage upon cure, have no (or little) volatile organic components, are applicable by a variety of methods (dip coating, roller coating, injection molding, or film casting), can be applied in a variety of thicknesses (10-100 m), are fast-curing, and possess robust physical properties. Particular attention focuses on the refractive index in the visible spectrum, light transmission, and formulation viscosity.

Thermally curable hybrid high refractive index polymer solutions have been developed. These solutions are stable up to 6 months under room temperature storage conditions and can be easily spin-coated onto a desired substrate. When cured at elevated temperature, the hybrid polymer coating decomposes to form a metal oxide-rich film that has a high refractive index. The resulting films have refractive indices higher than 1.90 in the entire visible region and achieve film thicknesses of 300-900 nm depending on the level of metal oxide loading, cure temperature being used, and number of coatings. The formed films show greater than 90% internal transmission in the visible wavelength (400-700 nm). These hybrid high refractive index films are mechanically robust, are stable upon exposure to both heat and UV radiation, and are currently being investigated for microlithographic patterning potential.

Photo-curable optical polymers have established for a wide range of micro-optical applications due to the great flexibility of their processing. Photolithographic patterning of these materials is often the basis for the fabrication of complex micro-optical elements and 3D microstructures. But, in the past, the optical functionality of “thick” microstructures (>50 μm) fabricated by UV-lithography was often limited due to an inhomogeneous internal refractive index distribution. Experiments showed that a homogeneous exposure of an UV-sensitive polymer will not lead to a homogeneous degree of polymerization, but to waveguide-like filament patterns. For photo-initiated polymerization processes a saturable and integrating non-linear refractive index change during the exposure process is characteristic. We present a general analytic analysis which shows that this non-linear material response leads to a modulational instability (MI) of the exposure light, if a certain degree of spatial coherence is exceeded. Then, perturbations of the incident wave are growing during propagation and the wave decays into filaments with well-defined spatial modulation frequency. It will be shown that these effects are characteristic for photosensitive polymers and different from the conventional MI, e.g. in Kerr-like media. Besides MI, the geometry of the resulting 3D patterns strongly depends on the initial intensity and phase distribution. If the degree of spatial coherence is below the threshold value, initial perturbations are not amplified. Therefore, it will be shown that the choice of suitable coherence properties or the specific modification of the spatial coherence of the effective light source within the lithographic patterning is a capable method to improve the homogeneity of optical microstructures. All theoretical results could be proven successfully within experiments.

Recently we have developed a novel slab optical waveguide (SOWG) spectroscopy utilizing glycerol drop on a thin glass plate for light introduction, with which in situ absorption spectra of adsorbed materials in UV-visible range were measured. This SOWG system has some advantages such as a low loss, a broad-band transparency, an easy coupling, and high sensitivity under monolayer coverage. Additionally, we have utilized indium-tin-oxide (ITO) electrode thin film on a SOWG (ITO-SOWG) for in situ observation of electrochemical reactions on electrode surface. We have observed the adsorption behavior of proteins and dyes on solid/liquid interfaces and obtain the electrochemical responses of them.

A variable optical attenuator employing an electrooptic Kerr material as the functional cladding of a silica waveguide is shown to switch in less than 1 microsecond with an extinction ratio greater than 15 dB. The VOA is designed to operate at 70 C and the electrooptic material has a refractive index that is less than the silica waveguide at that temperature. Methods for achieving low polarization dependent loss are outlined. An electrooptically-induced half-wave plate is shown to provide polarization independent performance with polarization dependent loss less than 0.6 dB at 19 dB of attenuation.

A new type of novel all-fiber power splitter has been designed and experimentally demonstrated, which could be directly applied to very short reach (VSR) passive optical networks (PON) based on hard polymer clad fibers (HPCF). Overcoming silica glass manufacturing difficulties, we successfully developed a 4x4 HPCF star coupler using a micro hydrogen-burner flame brushing. The device showed an excellent uniformity in power splitting ratio along with a very low excess loss of 4.58dB and insertion loss of 10.5dB over a wide wavelength range 600-900nm. Transmission quality and power budget for PON using the devices were analyzed for 1.25 and 2.5Gbps at 10, 25, 50m, whose results confirmed highly practical potential of the proposed device in VSR PON systems with a reasonable power budget.

We report on the reliability of state-of-the-art integrated dynamic polymeric photonic components developed for the telecommunications market. Tests conducted include full Telcordia GR-1209-CORE/GR-1221-CORE qualification, as well as accelerated aging tests that significantly exceed Telcordia requirements, such as aging at extreme temperature (5000 hours at 175°C) and optical power (6000 hours at 1.5 W of 1550 nm light). The types of components we describe include variable optical attenuator arrays, intelligent optical cross-connects, and fully reconfigurable optical add/drop multiplexers.

A micro-mirror formed using excimer laser processing for a fluorinated polyimide waveguide film was demonstrated. The tilted excimer laser irradiation to the waveguide core formed a micro-mirror with an angle of 45 +/- 1-degree. The micro-mirror had convex profile and exhibited a lens effect as a concave mirror. The micro-mirror, as formed, exhibited a low reflection loss of approximately 0.6dB at a wavelength of 850nm. This technique applied to flexible optical and electrical circuit board.

We report on the results of our study on the design, fabrication and integration of micro/nano-scale waveguide arrays and devices for applications for a modular system that we newly proposed and call "optical printed circuit board (O-PCB)," which we envision to use as a platform for VLSI micro/nano-photonic applications. The O-PCBs are designed to perform the functions of transporting, switching, routing and distributing optical signals on flat modular boards or substrates. We have designed and assembled O-PCBs using polymer-based optical waveguide arrays and circuits. We describe the procedures for the synthesis of polymers, procedures of forming masters and stamps, and procedures of forming waveguides using embossing techniques. We also describe the procedures of design, fabrication and construction of O-PCBs and describe the procedures for light coupling between light sources, detectors, waveguides and other functional devices. We also describe design of power beam splitters and waveguide filters using photonic band-gap crystals for VLSI photonic integration application. We also discuss the characteristics of the assembled O-PCBs and discuss their potential applications.

The variable optical attenuator (VOA) is an important part of agile optical telecommunication systems. VOAs built on so called free space technologies carry important drawbacks in terms of mechanical reliability, size and optical loss. Evanescent field approach have been used to design VOAs with very low insertion loss. Thermo-optic modulation mechanism was mainly used to control the attenuation level, which unfortunately requires from 10 to 100 times more electrical power compared to above mentioned free space architectures. This power consumption issue may be very challenging in high count arrays of VOAs. At the same time, liquid crystals (LC) have been proved to require very low electrical power for operation. In the present work, we report the creation of evanescent field modulation based VOA with extremely low insertion loss (below 0.1dB) and low electrical power consumption by removing a portion of the original fiber's cladding and replacing it by a specifically synthesized composite LC material, which have an ordinary refractive index lower than the glass one. The initial orientation of LC molecules provides an effective refractive index of the electro-optic cladding that is equal to the refractive index of the original silica cladding. We then create a LC molecule reorientation by the so-called Fredericksz effect by applying to the LC material an electrical voltage. This reorientation changes the refractive index around the depressed cladding area and brings to the partial leakage of the guided radiation into the cladding area, achieving thus attenuation levels above 50dB. Measured maximum electrical power consumption of the VOA is in the microwatt range.

Organic nonlinear optical crystal 2-Adamanthylamino-5-nitropyridine (AANP) has attracted attention because of its large nonlinear susceptibility and the possibility of phase matching in the near-infrared wavelength region. To achieve high efficiency of propagation and modulation of light, it is necessary to fabricate optical waveguides of the crystal. Electron beam irradiation method is well known technique for polymer pattering in the order of nanometer. In this work we apply electron beam irradiation method to AANP single crystal to modulate refractive index of it and fabricated an optical waveguide.

Surface enhanced second harmonic generation experiments on supramolecules: macrocycles, catenanes and rotaxanes, monolayers and multilayers deposited by vacuum evaporation on silver layers are reported and described. The measurements show that the molecules are ordered in thin films. The highest order is observed in the case of macrocycles and the lowest in thin films of fumaramide [2] rotaxanes. Also a better ordering is observed in the case of monolayers. The observed second harmonic generation activity is interpreted in terms of electric field induced second harmonic generation. The electric field contributing to SHG signal is created by silver atoms on the surface of silver layers. The measured second order NLO susceptibilities for a fumaramide [2] rotaxane is compared with that obtained by considering only EFISH contribution to SHG intensities. The electric filed on the surface of silver layer is calculated using TINKER molecular mechanics/dynamics software and the Embedded Atom model. An excellent agreement is observed between the calculated and the measured SHG susceptibilities.

Several potentially conducting polymers, optically nonlinear polymers, and biomaterials contain heterocyclic structures. Reduction of the energy band gap of a conjugated polymer is a topic of considerable interest due to the possible elimination of doping in the preparation of highly conductive polymers. Control of the energy gap value of a polymer by molecular design could modify its optical, electronic and optoelectronic properties. Thiadiazoles and their derivatives are the structural basis of some of these polymeric materials. The results of the calculation of the HOMO-LUMO gap, the dipole moment and polarizability of thiadiazole oligomers in vacuo and in the presence of solvents are reported. The calculations are based on density functional theory using a specially tailored model chemistry. The potential utility of these materials for the development of chemical sensors is discussed.

In this paper, we report a novel technique that combines push-pull Mach-Zehnder modulator structure with dc bias to achieve fractional volt half-wave voltage in intensity modulation. The technique is accomplished by simultaneously applying a common mode operation voltage and a differential dc bias voltage on the two arms of a Mach-Zehnder modulator. The modulators are tested for half-wave voltage at different temperatures while applying different push-pull biases. The results are compared with a push-pull EO polymer modulator that has identical dimensions and the same materials, and which is fabricated and poled with conventional method. It is found that our new approach reduces the half-wave voltage by a factor of more than five.

A uniaxial refractive index anisotropy was introduced by a corona poling. And, and biaxial refractive index anisotropy was introduced by a physical film stretching with the presence of the nonlinear optical chromophore. The refractive indices of the film before poling and after the poling were n_x=n_y=n_z=1.541 and n_x=n_y=1.539, n_z=1.552, respectively. The mechanical stress was then applied to the film to introduce another anisotropy. The refractive indices after the stretching were n_x=1.540, n_y=1.538, and n_z=1.551. We also proposed an in-situ film elongation technique with poling. Above the grass transition temperature, the polymer film is plasticized and can be stretched longer so that the chromophore is reoriented effectively. As a result, the decreasing of film transparency due to the stretching can be prevented by this temperature.

Highly photosensitive organic phototransistors (OPTs) with an organic thin film transistors configuration based on a biphenyl end capped fused bithiophene oligomer (BPTT) and copper phthalocyanine (CuPC) were prepared. The measured maximum responsivity and the ratio of photocurrent to dark current (IPh/IDark) in BPTT and CuPC OPTs were 82 A/W, 2 A/W and 2.0 × 10⁵, 1000 under 365 nm UV light with 1.55 mW/cm², respectively. The prepared OPTs showed a photocurrent response similar to the photo to current conversion efficiency (IPCE) spectrum of BPTT and CuPC. The main mechanisms responsible for photocurrent amplification in the devices were examined by comparing theoretical and measured data. The photovoltaic (turn-on) and photoconductive effect (turn-off) of the OPTs were determined by fitting to theoretical equations. The findings confirmed that the operation of the OPTs followed as photo-voltaic (turn-on state) and photo-conductive (turn-off state) behaviors.

Solar cells based on organic and inorganic materials are an emerging technology for a new generation of photovoltaics (PV). Hybrid solar cells, which use both organic and inorganic components, have advantages such as cost-effective processing and the ability to fabricate devices on flexible substrates. The combination of organic materials with semiconductor nanostructures allows enhancement of the conversion efficiency due to the fast electron transport in semiconductors and a high interface area between organic and inorganic components. In our work, anodized porous Si (PSi) was chosen as a host matrix filled with Copper Phthalocyanine (CuPC) molecules. The resulting nanocomposite can yield high performance novel materials for solar cells. The fabrication of PSi was completed using electrochemical etching of Si in diluted hydrofluoric acid (HF). Also, this process, with some modifications, can be applied to produce free-standing PSi films of desired thickness. PSi layer was filled with CuPC dissolved in concentrated sulfuric acid. The top contact was made by sputtering of Au or ITO. A power conversion efficiency (PCE) of 3% (33 mW/cm²) was obtained for 12 um thick n-type pSi layer with pore sizes of approximately 15 nm filled with CuPC. The electrochemical etching of Si under different conditions was carried out to optimize the photovoltaic parameters. A detailed investigation of the solar cell performance depending on porous layer thicknesses and pore sizes is presented. The use of free-standing films of PSi can lead to the fabrication of novel PV solar cells on flexible substrates with high conversion efficiency.

We present an enhancement scheme for optical extraction from Organic based LEDs (OLEDs). Enhancement layers, developed by Mitsubishi Chemical Corporation, facilitate the engineering of scattering near an OLED's emitter. An approximate scattering model based on rigorous optical field calculations of the OLED structure is described and optimised. Experimental and numerical results indicate that up to 2-fold efficiency enhancements are achievable across a broad spectral range.

Holographic polymerization of liquid crystal containing photopolymerizable resins enables one-step, rapid formation of multi-phase structures that exhibit partial photonic band gaps. These holographic polymer dispersed liquid crystals (H-PDLCs) provide a versatile platform for diffractive optical elements because the structures are not limited by multi-phase equilibrium but are controlled by the interference of multiple lasers at discrete angles. Incorporation of laser dyes into H-PDLCs form 1-D and 2-D optically pumped distributed feedback lasers. Linewidths as narrow as 1.8 nm are observed with laser thresholds below 1 mJ/cm² in 2-D columnar structures compared to 9 nm and 25 mJ/cm2 exhibited by 1-D H-PDLC Bragg stack lasers. In the 2-D lattices the energy of the laser action can be tuned within the gain spectrum of the lasing medium by an applied electric field.

We demonstrate optical signal amplification in a solid-state dye-doped polymer with a rib waveguide structure. The device consists of a 1μm x 120μm poly(methyl methacrylate) (PMMA) waveguide, doped with 1% by weight Rhodamine 640 dye, spin coated onto a silica substrate. A 625nm pulsed signal and a co-linear 575nm pump are facet coupled into the waveguide and optical amplification of the signal is demonstrated. Depending on the signal intensity, a maximum internal gain in the 21-26dB range at 625nm is achieved using a 1.2cm long waveguide. The device exhibits a promising signal-to-noise ratio in the 9-16dB range and has the potential for tuning in a 40-50nm wavelength window with the same dye, and throughout the visible spectrum using other dyes. The wavelength operating range of this device is also analyzed. We therefore present a compact, easy to fabricate, high gain block suitable for use in conjunction with plastic optical fibers, which have a low-loss window at around 640nm. Since most of the optical amplification takes place in a short region (<10μm), an even more compact device geometry can be envisaged using a shorter waveguide.

The procedure for increasing the temperature and electric field to set poling conditions for guest-host nonlinear optic polymers was evaluated. Specifically, the order of the two variables was alternated and the poling efficiency was evaluated by comparing the electro-optic coefficient, r33 for both procedures. Two host polymers, poly(methyl)methacrylate (PMMA) and poly[bisphenol A carbonate-co-4,4'(3,3,5-triethyl cyclohexylidene) diphenol] (APC) were doped with 10% (by weight) of the chromophore disperse red 1 (DR1). Single layer films were spin deposited onto a glass substrate with patterned indium tin oxide (ITO) as the bottom electrode and patterned gold as the top electrode. With the final set poling temperature and electric field held constant, each system was poled under two different poling procedures. The first procedure was to increase the temperature at a constant rate first and then increase the electric field at a constant rate to the final set poling conditions, and conversely, the second procedure was to increase the electric field at a constant rate, at room temperature, first and then increase the temperature at a constant rate to the final set poling conditions. An increase in poling efficiency was found for the 'Voltage then Temperature' procedure in both guest-host systems with an increase in r33 values of 38% to 43%. While this dramatic increase is not expected for every system, it shows that there is an additional variable of poling procedure that can be modified for enhancing the efficiency of poling.

A number of studies are currently focused on using polymers derived from salmon DNA as the primary ingredient in the design of optical waveguide devices. Although the long term goal is to develop optical devices for rapid chemical and biosensing, this work was aimed specifically at studying the response of a planar DNA waveguide to ammonia in nitrogen and air with controlled amounts of humidity at ambient temperatures. This follows the work of S. S. Sarkisov et al. who used PMMA and other polymer films doped with the indicator dye bromocresol purple (BCP). These devices are characterized by absorption sensitivities of the order 0.1 dB attenuation of the transmitted light signal per 100 ppm change in the NH3 concentration with response times of better than 1 ms and can be recycled with no loss of sensitivity. The performances of waveguide devices using films fabricated with high and low molecular weight DNA with BCP are compared to BCP-doped PMMA devices.

Optical and photochromic properties of spiropyran-doped DNA-surfactant complex films have been studied. They strongly depended on the type of spiropyran as well as the type of surfactant. Spiropyrans containing the oxazine ring and intercalated into DNA showed very rapid photochromic response. It is also shown that photochromic response times are expected much faster by increasing the intensity of the excitation light.

In order to clarify the mechanism of ultrafast optical nonlinearity in polymer especially polydiacetylene real-time measurement of molecular vibration which can provide information of time-resolved structural changes associated with huge electronic spectral change was performed. Molecular vibration of several modes in blue-phase polydiacetylene-3-butoxycarbonylmethylurethane (PDA-3BCMU) was time resolved by 5-fs pump-probe measurement. The contributions of the vibrational wavepackets in the ground state and in the excited state in the signal were separated by multi-channel measurement. The C=C stretching mode in the ground state starts to oscillate π-out-of-phase with the C^≡C stretching mode. The structure of PDA-3BCMU in the geometrically relaxed state is not pure butatriene-type but more like acetylene-type. The frequencies of C=C and C^≡C stretching modes there were determined by singular value decomposition method to be 1472 ± 6 cm^-1 and 2092 ± 6 cm^-1, respectively. The double and triple bond stretching frequencies in the ground state which are 1463 ± 6 cm^-1 and 2083 ± 6 cm^-1, respectively. Frequencies of both modes are increased in the configuration after the geometrical relaxation after the generation in the excited state upon excitation.

Obtaining of thin ordered films from several π electron conjugated systems, such as poly(3-alkyl thiophenes) (PAT), polyaniline (PANI), polyparaphenylene (PPV) and from a sexithiophene oligomer (6-T) is described and discussed. Three thin film fabrication techniques: spinning, drawing and vacuum evaporation are used and compared. The spinning technique gives good optical quality thin film with an "in plane" order. The polymer chains align preferably parallel to the substrate plane. The drawing technique leads also to a partial orientation of thin films with polymer chains preferably oriented either in the drawing direction or perpendicular to it, depending on concentration and the drawing speed. The degree of order is studied by the linear dichroism technique and the optical birefringence. In the case of sufficiently good optical quality the thin film refractive indices, their anisotropy and dispersion were determined by the m-lines techniques. The nonlinear optical properties of thin films were measured by the optical third-harmonic generation.

The two-photon absorption (TPA) properties of beta-carotene in chloroform solution were investigated over the 590-790 nm wavelength range. The TPA was characterized using the open-aperture z-scan technique with picosecond pulses provided by a widely traveling-wave optical parametric amplifier (OPA) pumped with a Ti:sapphire laser amplifier. We found the 0.2-1 cm/GW values of two photon absorption coefficient in the 725-790 nm wavelength region. At shorter wavelengths, a dramatic increase in the two-photon absorption around 600 nm was observed. The observed two photon absorption dependence on the excitation wavelength can be explained by the onset of strong excitation from the ground state 1A_g to the higher lying two-photon allowed m₂A_g band centered around 310 nm (~4 eV).

The PbSe nanocrystals were synthesized without impurity from lead oleate and Se(TOP) by heating in phenyl ether. The particle size increases the synthesis temperature. The PbSe QD / PPA nanocomposite was made with the synthesized PbSe nanocrystals and the amine-containing PPA polymer by using the ligand exchange method. The PbSe nanocrystals were well dispersed in the PbSe QD / PPA nanocomposite. The PbSe QD / PPA nanocomposite film has the broad PL peak around 1300 nm with FWHM of ~ 170 nm. The time constant in the PbSe QD / PPA nanocomposite film is as slow as ~ 150 ns. We investigated the structures of the developed PbSe QD / PPA nanocomposite film as well as their optical properties, and then suggested their photonic applications.

The growth of nanoscopic oligophenylene and oligothiophene aggregates on muscovite mica by vacuum deposition has been investigated. In the case of para-phenylenes a dipole assisted self assembly generation of needle-like aggregates is observed on mica. At optimum fiber growth temperature phenylene aggregates grow in most cases without a layer of upright oriented molecules. In contrast, vacuum deposition of oligothiophenes results simultaneously in fibers of laying molecules as well as islands of upright molecules. Since both phenylenes and thiophenes are strongly polarizable but differ in the lattice parameters of the resulting crystalline overlayers a direct comparison between the two classes of molecules allows us to study the role of epitaxy on the growth of nanoaggregates. Besides straight aggregates we also observe thiophene rings on water and methanol treated mica surfaces, which consist of radially oriented, laying molecules.

In order to fabricate a homogeneous pyroelectric thin film of polymer-ceramic composite for un-cooled infrared sensors, ceramic particle size should be as small as possible. Nanoparticles of Lead zirconate titanate and lead zirconate type ceramic were obtained. In this presentation, electrical and pyroelectric properties of PVDF:PZT composite films prepared by Spin-Coat technique are presented, and results are compared with other triglycine sulfate based composites.

A series of new polyesterimides (PEIs) containing photochromic azobenzene moieties have been synthesized. For this purpose the following diesterdianhydrides with azobenzene groups have been prepared: 2,2'-{4-[(4-nitrophenyl)-azo} phenyl]iminobis(ethyl benzene-1,2-dicarboxylic acid anhydride-4-carboxylate), 2,2'-{4-[(4-methylphenyl)-azo}phenyl] iminobis(ethyl benzene-1,2-dicarboxylic acid anhydride-4-carboxylate) and 2,2'-{4-[(4- fluorophenyl)-azo}phenyl] iminobis(ethyl benzene-1,2-dicarboxylic acid anhydride-4-carboxylate). The polyesterimides have been obtained from diesterdianhydrides and 1,3-phenylenediamine using high-temperature polycondensation. The resulting polyimides are characterized as having good solubility in some solvents, high glass transition temperatures (168-210°C) and good film forming properties. The irradiation with linearly polarized light causes a reorientation of the azobenzene groups by angular-selective E/Z photoisomerization. In this way optical anisotropy is induced in the initially isotropic films casting from solution of the amorphous polymers. The photoinduced dichroism in the films has been measured to investigate the effect of azobenzene substitution.

Novel azobenzene functionalized poly(amide-imide)s (PAIs) having azo-benzene group in side chain of polymers were prepared. FTIR spectroscopy and elemental analyses confirm structure and the existence of azo-benzene chromophores in obtained polymers. The relationship between structure of polymers and their physical and optical properties was studied. Thermal behaviour such as glass transition temperature and thermal stability were measured. The influence of the main chain structure of poly(amide-imide)s on polarization gratings recording using standard degenerate two-wave mixing technique with 514.5 nm Ar+ laser line has been investigated.

Organic materials have great potential for electro-optic devices. Achieving higher unidirectional ordering of chromophores is the main challenge in using organic materials in such devices. The prime reason for this decreased order is due to interchromophore interactions which lead to a decrease in the electro-optic coefficient, r33. A material consisting of a chromophore surrounded by dendrons and possessing an appropriate aspect ratio should facilitate the near Ferro-electric ordering as observed in the discotic liquid crystals. For that purpose, a prototype dendrimeric chromophore has been synthesized and will be used in Mach-Zehnder devices to achieve lower drive voltages.

A waveguide lens composed of multistage polymer-filled thin grooves in a silica planar lightwave circuit (PLC) is proposed and the low-loss structure is designed. Both an imaging optical system and a Fourier-Transform optical system can be configured in a PLC by use of a waveguide lens. It makes a PLC functional and its design flexible. Moreover, a focal length of a lens is tunable with large thermo-optic effect of the polymer. A concatenated lens is formed to attain a desirable focal length with low-loss. The thickness of each lens and the spacing are about 10-50 microns. The simulation showed that the radiation loss of the light propagate through 20-stage grooves filled with a polymer was only 0.868 dB when the refractive index of the polymer was 1.57, the groove width was 30 microns, and the spacing between adjacent grooves was 15 microns. For example, the single lens structure that the center thickness is 30 microns, the diameter is 300 microns, and the refractive index of the polymer was 1.57, have a focal length of 4600 microns. The focal length of 450 microns can be obtained with 20-stage concatenated lens structure. The larger numerical aperture can be realized with a polymer of higher refractive index. We have applied the concatenated lens structure to various photonic circuits including optical couplers, a variable optical attenuator.

Thermo-optic coefficients dn/dT for TE- and TM-polarized lights (dn_TE/dT and dn_TM/dT, respectively) were measured for aromatic polyimide (PI) films formed on Si Substrates. The values of dn/dT for the average refractive index (dn_av/dT) is in a range of -52 to -87 ppm/K, and amorphous PI films with large n_av have large |dn_av/dT|, which is well accounted by the temperature derivative of the Lorentz-Lorenz equation. On the other hand, the absolute values of dn_TE/dT were significantly larger than those for dn_TM/dT even for the PI films with very small polarization dependence in refractive index (Δn; in-plane/out-of-plane birefringence). This result cannot be explained by the temperature derivative of the Vuks equation, which represents that the large polarization dependence in dn/dT is caused by the large Δn. Polarization dependence in dn/dT for the PI films with small Δn is caused by the temperature dependence in large stress birefringence. Based on these results, large thermal expansion and small stress birefringence (small residual stress or small polarization anisotropy) is essential for achieving large |dn_av/dT| and small polarization dependence in dn/dT. To demonstrate this assumption, dn/dT measurements were carried out for PI films derived from a fluorine-containing dianhydride and aliphatic diamines, which exhibit loose chain packing and small polarizability anisotropy. As a result, these PI films exhibit small polarization dependence in dn/dT, and relatively large dn_av/dT compared to the aromatic PI films with almost the same n_av.

The principle, experiment setup and experimental results of a novel process of controlling the nanoparticle distribution in hydrogel by utilizing the theory of electrophoresis are discussed and demonstrated. The distributed nanoparticles in hydrogel changed the refractive index of the material, which provide the new application for organic gradient refractive index (GRIN) lens. For conducting the electrophoresis experiments, two miniaturized electrophoresis running tools have been designed and fabricated. The dimensions of vertical ruing tool is about 4 x 3 x 3.5 cm (L x W x H). In order to clearly observe the running results, the process of self-assembly are used to label the nanoparticles with fluorescent dye. The silica nanoparticles (7-9 nm in diameter) are being investigated to explore its effect on the optical improvement of hydrogel material. Polyacrylamide hydrogel is used as lens material. Various analysis equipments are employed to characterize the samples, including X-ray photoelectron spectroscopy (XPS), thin film measurement system and fluorescent microscopy. The experimental results from fluorescent microscope have shown that nanoparticles were moving toward the opposite charged electrode from particle resource and distributed according to the electrical field. For GRIN lens application, the electrophoresis phenomena have also been investigated by the testing setup with a circular electrode (3 cm in diameter). The testing results were examined by thin film measurement system and X-ray photoelectron spectroscopy. With the data of analyzed Si concentration, it has been proven again that the distribution of nanoparticles could be controlled by electrophoresis in hydrogel film which presents the radial gradient refractive index profiles. The refractive indices change range could be larger than 0.06. The simulation results with CoventorWare@ also predicted the nanoparticles movement and distribution in hydrogel under electrical filed with different values of electrophoretic mobilities.

In this work we describe a lithographic technique for fabrication of Fresnel lenses. This technique is achieved using a photo mask and Norland Optical Adhesive No. 65. The main characteristics of this lens are his low cost and its flexibility due to the material. Some experimental results are shown.

We have developed a novel approach for fabricating and testing optical ring resonators. Using a side-polished optical fiber and fabricating a ring waveguide directly over its core, an efficient and passive signal filter in the 1.55 um telecommunication band is created. A standard single mode optical fiber is permanently secured in an arcing groove in quartz and is side polished proximally to its core. The ring resonator is fabricated using two-photon initiated free-radical polymerization of tri-functional acrylate on low-index quartz substrate with a 100 femtosecond pulsed Ti/sapphire laser. The quartz substrate is inverted and vacuum mounted to an X-Y-Z stage so that the polymer ring waveguide can be positioned directly above the core of the fiber forming a vertically coupled ring resonator. Our technique allows infinite variation of the width, height, diameter and location (therefore the coupling strength between the fiber and the ring) of the ring resonator waveguide. This approach enables resonators to be fabricated, tested and subsequently removed multiple times on the same side-polished fiber, refining both the ring resonator geometry and materials. Because it is a fiber-based device, it possesses negligibly low optical insertion loss and can be used for fixed and tunable wavelength filters, intensity modulators, and fiber-optic sensors. Both theoretical analysis and experimental data will be presented.

Low drive voltage Mach-Zehnder modulators were designed and fabricated using proprietary EO polymers with high electro-optic coefficients. We report on drive voltage and high-speed electrode parameters of modulators fabricated on silicon wafers with high yield. Special attention was paid to designing claddings to match the electro-optic core conductivity and dielectric constant. The r33 values measured on single layer thin films are compared with those resulting from drive voltage measurements on devices. Half-wave voltage measured on devices is compared with theoretical values derived from equations defined for poling of the core through bottom and top claddings. We compare results obtained from devices fabricated using commercially available UV-curable epoxies with devices fabricating using proprietary clad polymers developed at Lumera Corporation.