We present a study of Distributed Feedback laser emission in various polymer materials. This laser scheme permits efficient control of the stimulated emission in dye doped polymer materials. Optical feedback is provided by distributed Bragg gratings formed in the film by interference patterns from the pump beam. We demonstrate broad tunability of laser emission in polymeric waveguides doped with stilbenoid, phenylene vinylene and oligomers of phenyl ethynylene used for OLEDs. Laser action was also obtained with Rhodamine 6G in PMMA deposited on surface relief grating and excited in a transverse single beam pumping geometry.

The optical properties and characteristics of rare earth- doped polymers have been studied to evaluate their viability for use in optical amplifiers. Rare earth ions are encapsulated in organic, covalently bonded chromophores. The optical properties of various rare earth chromophores doped into polymers are measured and calculated and are then used in numerical simulations of amplifiers and lasers. The result provide an estimate of their potential device performance and establish the fundamental bases for applications in photonics. Owing to their distinct advantages, such as chromophore energy transfer effects, high rare earth ion concentrations, shielding of the ion form high energy vibrations of the host, enhanced optical transition moments and controllable decay rates and branching ratios, rare earth-doped polymers are found to be promising candidates for various device applications. Numerical simulations for samarium and europium doped polymers indicate that gains about 10 dB and greater are achievable in relatively short polymer optical fiber and waveguide amplifiers. Studies of the dependence of metastable state lifetime of rare earth doped polymer systems on doping concentrations reveal that rare earth chromophores dissociation occurs at low concentrations. These results are used to optimize the parameters of our rare earth doped polymer optical waveguide amplifiers.

We report on the lasing action of the graded-index polymer optical fibers containing dyes, such as Rhodamine B, Rhodamine 6G, Perylene Orange, and Pyrromethene 567. These dyes have been incorporated into poly(methyl methacrylate- co-2-hydroxythyl methacrylate). These fibers were transversely pumped at 532 nm with a frequency-doubled Q- switched Nd:YAG laser. Slope efficiency of 24 percent and output of 1.2 mJ were obtained with a Rhodamine 6G-doped fiber. A lifetime of 200,000 pulses at 10 Hz was achieved with a Rhodamine B-doped fiber. GI POF containing a Nd- chelate have also been fabricated. The absorption spectrum of the fiber exhbit3ed several strong bands in the visible and IR regions. We have observed IR fluorescence of the Nd³⁺ ion of the fiber at room temperature when it was pumped with an Ar⁺-pumped dye laser at 580 nm. The Judd-Ofelt theory was applied to the absorption spectrum of Nd³⁺ in polymer to determine the Judd-Ofelt parameters. From the theory, various radiative properties, such as transition probability, branching ratio, and emission cross section for various emission levels, have been determined and reported.

We find a ring structure in the far field of laser radiation emitted from a dye-doped cholesteric liquid crystal (CLC) film. This is a consequence of angular confinement of radiation at the frequency of the mode propagating normal to the molecular layers, which lies closest to the reflection band edge. This is a result of the increase in frequency of the band edge with increasing angle from the normal, which places oblique radiation at the frequency of the band edge for normally propagating radiation inside the photonic gap. As a result, the intensity along the output surface of the film decays exponentially on a length scale that can be much larger than the film thickness. This in turn gives rise to a ring structure in the far field that is similar to Fraunhofer diffraction of a plane wave by an aperture. These results apply not only to CLC films but also to binary layered media.

The performance of many integrated photonic deices is often determined by the accuracy by which the structure can be defined and ultimately fabricated. However the manufacture of highly defined vertices in photonic structures is often limited by the mask quality and by the limited resolution obtainable by standard photolithography. A simplified fabrication technique is presented here, that offers advantages over previously reported methods for the fabrication of highly defined vertices in polymeric integrated optical components so overcoming these limiting factors. The application of this technique for the fabrication of 2D integrated optical wavelength division multiplexing components is demonstrated. The possible application of this component to the low cost datacom market is also reviewed and compared to competitive technologies. The advantages of the technique is discussed and the improved resolution obtainable in comparison to standard single mask photolithography is illustrated.

A key property that differentiates optical polymers from more conventional optical materials such as glass, is the rapid variation of the refractive index with temperature. This large difference in dn/dT can be leveraged to produce efficient thermo-optically active optical components. An advanced polymeric waveguide technology was developed for affordable thermo-optically active integrated optical devices that address the needs of the telecom industry. We engineered high-performance organic polymers that can be readily made into single-mode waveguide structures of controlled geometries and of modal profiles that closely match standard telecom glass fibers. These materials are formed from highly-crosslinked halogenated acrylate monomers with specific linkages that determined properties such as flexibility, toughness, optical loss, thermal stability, and humidity resistance. These monomers are intermiscible, providing for precise continuous adjustment of the refractive index over a wide range. In polymer form, they exhibit state-of-the-art loss values, suppressed polarization effects, and exceptional environmental stability. The devices we describe include thermally tunable Bragg-grating-based wavelength filters, thermally tunable arrayed-waveguide gratings, and digital optical switches.

Using Cyclic Transparent Optical Polymer (CYTOP), a perfluorinated graded index fiber, different transmission characteristics were investigated. Graded index perfluorinated fibers can support multi-Gb/s date rates form 0.83 um to 1.3 um. High bit rates can be obtained over 0.5 um wavelength range where optical transmitter and receivers technologies are already matured. A distributed feedback laser source at 1.3 um and a low cost InGaAs detector had been used in an error free transmission for both modulated multichannel transmission and directly modulated digital transmission for both modulated multichannel transmission and directly modulated digital transmission at 2 Gb/s. Two data channels at 145 Mb/s are mixed using binary phase shift keying BPSK modulation technique index of 5.3 percent. Also, the dispersion power penalty of the CYTOP fiber was measured and found to be less than 1 dB suggesting that the fiber induced distortion is small.

A turn-key system for holographic interferometry with bacteriorhodopsin films as optical recording media is presented. Four inch wide bacteriorhodopsin films are used for lensless holographic recording. No consumables are required for operation. Several interferometric techniques like time-averaging, real-time, double-exposure and the phase-shifting method can be realized with the same system. Switching between the different operation modes is possible under software control within a few seconds. An additional feature is that the system may be used for the determination of the dimensions of the investigated objects with a resolution down to several micrometesr. The optical setup is presented. The properties of the bacteriorhodopsin films installed, in particular their optical homogeneity, the exposure required, their holographic diffraction efficiency and their hologram rise and erasure times, are discussed. The optical resolution of the bacteriorhodopsin films of 5000 lines/mm is far beyond that of the rest of the holographic system which is limited mainly by the CCD camera used for read-out. Optical setups with higher and variable optical read-out resolution are presented which allow to exploit the capabilities of bacteriorhodopsin films to a better extent.

The photoinduced reversible color change and in-situ recording of fulgide Aberchrome 670 doped polymethyl methacrylate (PMMA), cellulose acetate (CA) and polystyrene (PS) were investigated. Upon UV and visible exposure, closed-form absorbency followed first-order kinetic. The rate constants K_UV and K_VIS for respectively the coloring and bleaching process were determined. In PMMA matrix K_UV equals 1.2 * 10^-3 s^-1 and K_VIS equals 11.1 8 10^-3 s^-1, in CA matrix k_UV equals 2.7 * 10^-3 s^-1 and k_VIS equals 6.4 8 10^-3 s^-1 and in the case of PS film k_UV equals 2.1 * 10^-3 s^-1 and k_VIS equals 11.9 * 10^-3 s^-1 were obtained. These results show that, K_VIS is much larger than K_UV for all matrices. Photochemical fatigue resistance in different polymer matrices was investigated. We found a loss of 9, 11 and 13 percent in PS, CA and PMMA respectively, after 10 repeated UV and visible cycles. The real time holographic recording in fulgide doped PMMA films were studied. We have analyzed the effect of the photochromic concentration, the thickness of the film and the recording intensity on the diffraction efficiency. The highest diffraction efficiency is obtained for the concentration of 5 percent of the fulgide dye in PMMA film with an exposure energy of 10 mw/cm². For the same sample we have not observed any diffraction beam when the sample was illuminated by an intensity of 3 mw/cm².

In this paper, the optical nonlinearity and multiplex holographic storage using azo side-chain polymer are studied by degenerate four-wave mixing and polarized light pump- probe method with a Ne-Ne laser. The He-Ne laser wavelength is located in the tail of absorption peak of sample. This material shows high diffraction efficiency of gratin and information storage capability in the case of weak absorption. The diffraction of grating is up to the order of 10^-2. The effect of polarization beams on grating is studied. The diffraction efficiency of grating is least in the case that the polarization of readout beam is orthogonal to that of both writing beams. An angle multiplex holographic storage in the sample is performed and information can be stored for long-term in room temperature. The information readout of multiple holographic storage in the samples can be controlled by the polarization of readout beam. The diffraction deficiency of grating versus temperature of sample is studied. It is demonstrated that the higher temperature under the melt-temperature the sample has, the larger diffraction efficiency and faster relaxation grating has. The grating is completely erased by increasing temperature over the melting-temperature of the sample. Reading the grating with a circular polarized light is not able to erase the grating. When two recording beams are turned off, great parts of the grating remains for a long- term beside few part of the grating degrades. The results show that the azo side-chain polymer is a good information storage material.

Photorefractive film of low T_g polymer composites of poly(N-vinylcarbazole): -(4-nitrophenyl)-(1)-prolinol: 2,4,7-trinitro-9-fluorenone: N-ethylcarbazol was fabricated at a weight ratio of PVK:NPP:TNF:ECZ equals 35:50:1:15 wt percent. Two-beam-coupling (TBC) experiment and four-wave mixing experiment were performed at wavelength of 633nm. A reversible photorefractive grating and an irreversible grating, were observed and distinguished. The TBC coefficient was measured to be 140 cm^-1 at E₀ equals 85 V/micrometers , corresponding to a photorefractive grating of 3.6 X 10^-3. The irreversible grating was measured to be about 7 X 10^-3, which was attributed to the NPP aggregation.

In this presentation, we discuss recent progress on polymer photovoltaic cells and polymer photodetectors. By improving the fill-factor of polymer photovoltaic cells, the energy conversion efficiency was improved significantly to over 4 percent. Such high efficiency polymer photovoltaic cells are promising for many applications including e-papers, e-books and smart-windows. Polymer photodetectors with similar device configuration show high photosensitivity, low dark current, large dynamic range, linear intensity dependence, low noise level and fast response time. These parameters are comparable to or even better than their inorganic counterparts. The advantages of low manufacturing cost, large detection area, and easy hybridization and integration with other electronic or optical components make them promising for a variety of applications including chemical/biomedical analysis, full-color digital image sensing and high energy radiation detection.

The spectral sensitization and photosensitizer efficiency of a liquid crystalline photoconductor, 2-(4'-octylphenyl)-6- dodecyloxy-naphthalene (8-PNP-O12) with C₇₀ were investigated by steady-state and transient photocurrent measurements in terms of temperature, electric field, and doping concentration of C₇₀. The C₇₀-doped liquid crystal cell exhibited a photoresponse in visible region of 400-700nm corresponding to the optical absorption of C₇₀. In the time-of-flight measurement, the fast transient photosignals with fast rise and decay on the order of microseconds were obtained even in a bulk excitation condition, which is governed by the ambipolar carrier transit. In visible region, the same photogeneration efficiency for hole and electron indicated that C70 can inject both electron and hole into 8-PNP-O12 when photoexcited. The phase transition temperature did not change by doping C₇₀ but the phase transition was found to have a great influence to the photogeneration yield. In the high ordering SmB phase, the photosensitization yield was found to be about two orders larger than that in the low ordering SmA phase and isotropic phase, where different interaction of C₇₀ was obvious in optical absorption and texture is under polarized microscope.

A novel approach to the deposition of high quality films of oligothiophenes has been developed. It is based on an original seeded supersonic molecular beam combined with an ultra high vacuum deposition chamber. This method gives an unprecedented control on film properties. Several quaterthiophene films under different beam conditions have been prepared and characterized by optical absorption, photoluminescence, tapping mode atomic force microscopy, secondary electron microscopy and x-ray diffraction. Morphology, structure and optical response are controlled by the beams' parameters. Highly ordered films, up to several hundreds of nm thick, show well resolved vibronic structures in low temperatures fluorescence spectra as only the best published data on films a few monolayers thick do.

We report electroabsorption studies of electric fields in organic light emitting diodes made form substituted poly(para phenylene vinylene) derivatives and solar cells made form zinc phthalocyanine (ZnPc) and perylenetetracarboxylic diimide (PTCDI). The electric field in LEDs is not proportional to the applied bias due to the development of an internal electric field during operation that opposes the applied bias. This counter field is weaker for devices measured in vacuum than for those measured in an ambient atmosphere and is no longer apparent for devices that were prepared and tested under an inert atmosphere. We also observed that the built-in potential increased with operating time. The combination of these two processes leads to an increase in the turn-on voltage of organic LEDs with increasing operating time. We have detected an electric field at the electrode/organic LEDs with increasing operating time. We have detected an electric field at the electrode/organic interface of organic solar cells which is insensitive to the external DC bias. The interface field has a different spectral signature from that of the bulk of the two layers and is attributed to charged transfer-induced dipoles. Rectifying behavior due to the formation of a pn junction under illumination is observed in bilayer solar cells, but not single layer devices made from ZnPc or PTCDI.

Experimental and theoretical results are presented on the lifetime of organic light emitting diodes (OLEDs) for active matrix display applications. DC aging tests on the OLEDs show that the driving voltage increases under forward bias and then reverse its trend when the bias polarity is reversed, which reproduce our previous test under AC conditions. Furthermore, the voltage seems to be able to relax slowly toward its initial value when the device bias is reset to zero after a long forward bias stress. The mobile ions are proposed to be the origin of the observed voltage shifts. By solving a system of transient equations governing the mobile ion motion under an external field, we obtained the transient mobile ion distributions and their contribution to the driving voltage. Several cases were studied. We found that the mobile ion model with reasonable assumptions could very well explain the experimental results. Furthermore, by comparison between the data and simulation, the possibility of the initial mobile ion sources can be narrowed.

Photoluminescence (PL), electroluminescence (EL) and degradation of a soluble electroluminescent poly(p- phenylene), SPPP,. And its blends with hole transport polymers based on PMPSi were studied. Efficient blue light- emitting devices (LEDs) with an air-stable electrode based on polymer blends composed of SPPP and PMPSi have been fabricated. In contrast to LEDs made of neat SPPP, an increase in external EL efficiency and improvement of the stability of blue emission were achieved in these LEDs. This enhancement is far above the increase in the PL efficiency of the blend layers. New alternately substituted poly(p- phenylene)s with high photoluminescent efficiency and new polymers with (pi) -conjugated or electron-transporting moieties attached to the polysilane backbone were synthesized.

Liquid crystalline conjugated polymers have potential applications as inexpensive, easy to process polarized back lights for liquid crystal displays. Two 'Hairy rod' type conjugated polymers have been investigated as polarized light emitting materials. In this paper, we present polarized absorption and photoluminescence for films aligned on rubbed precursor PPV alignment layers. We also report electroluminescence measurements for oriented multi-layer devices with rubbed PPV hole transporting alignment layers that produced polarization ratios of up to 25:1 and a luminance of 250 cd/m². Sample preparation, device fabrication and characterization are described. Preliminary investigations have been made into the performance of PPV as an alignment layer with respect to thermal degradation.

We present theoretical models and experimental results on the carrier transport mechanisms in single-layer organic alloy light emitting diodes. The typical organic alloy consists of a mixture of electron and hole transporting materials. The device shows significant improvement in lifetime at room and elevated temperatures. The improvement is attributed to the elimination of the heterointerface and the minimization of the formation of unstable tris-8- hydroxyquinoline) aluminum (Alq₃) cations. The efficiency is comparable to those of their heterojunction counterparts. Balanced bipolar carrier injection and transport are made possible by adjusting the alloy composition and doping. We model the device by assigning individual conduction channels to each type of material. The sensitivity of the diode efficiency on several key parameters is studied.

The authors investigated the electrical and optical properties of the organic light-emitting-diode (OLED) with a phenylbenzeneamine derivative (MDTPA). The PL and EL of MDTPA thin film were blue. However, the EL of the device of indium-tin-oxide (ITO)/MDTPA/aluminum quinoline (Alq3)/metal was not due to the emission from MDTPA, but was the emission from Alq3. It can be explained by that the emission region is formed in Alq3 layer since MDTPA has excellent hole transportation. The authors introduced an oxadiazole dimer (OXD) as a carrier blocking layer between MDTPA and Alq3 layers in order to from the emission region in MDTPA layer. This multi-layer OLED was found to have a high performance for a blue-light-emitting EL device. Its luminescence was over 3000 cd/m² at the current density of 100 mA/cm². The EL threshold voltage was about 5 V. Their EL efficiency was about 2 lm/W.

Structure and optical properties of vacuum deposited poly- para-phenylene (PPP) films were investigated by UV-Vis absorption, luminescence, polarized luminescence, FTIR, and electron diffraction methods. It was shown that molecular structure, morphology and spectral parameters of vacuum deposited PPP films drastically depend on evaporation temperature, substrate temperature and distance of substrate from PPP powder. The increase of the evaporation temperature results both in red shift of the luminescence peaks from 480 nm at 650 degrees C to 540 nm at 800 degrees C and in considerable decrease of the photoluminescence intensity. Electron diffraction studies show that the highest degree of crystallinity of PPP films is observed for evaporation temperature 680 degrees C and support temperature 300 degrees C. These conditions yield optically anisotropic films with high luminescence intensity on various substrates. Electron diffraction and polarized optical measurements of highly oriented PPP films indicate that PPP molecules are essentially arrange perpendicularly to the surface of the support. It has been demonstrated that in FTIR spectra of highly oriented PPP films an extremely strong band at 1375 cm^-1 is observed. That band is not typical for currently known PPP modifications and could be associated with change in the order of the 'defect' C-C bond between adjacent quinoid and benzenoid units.

In this work, electron-transporting chromophores were introduced to emission polymer to increase its electron affinity. Several emission chromophores also were synthesized to polycondensate with electron transporting chromophores. The influence of structure on optoelectric properties was investigated in detail. 2,5-Bis-(4- fluorophenyl)-1,3,4-oxadiazole and 9,10-dihydro-oxa-10- phosphaphenanthrene-10-oxide (DOPO) derivatives were used as electron transport and emission monomers, respectively. The DOPO derivatives that contain benzene, biphenylene or 1,4- naphthalene were synthesized. The emission units exhibits blue light as expected. Aromatic polyethers were obtained by nucleophilic displacement reaction of oxadiazole-activated bis(halide) monomers with bis(phenol) monomers. All the resulted polymers are thermally stable below 400 degrees C. The absorption peaks of these polymers vary between 325 nm - 350 nm, while the photoluminescence peaks vary between are 377 nm - 464 nm.

The dispersion of the first molecular hyperpolarizability (beta) of strongly charge-transfer chromophores is investigated. In the two-photon resonance regime, both dephasing and vibronic and vibronic structure plays an important role in affecting the molecular hyperpolarizability. An equation for (beta) that includes the effect of dephasing and vibrational structure of electronic states is derived. It is shown that, if only the dephasing mechanism is included in the two level model, the intrinsic hyperpolarizability (beta) ₀ calculated from the hyper- Rayleigh scattering experimental data using the Oudar-Chemla equation, will decrease with decreasing the excitation wavelength. The trend is reversed when the vibrational structure is also incorporated.

Polymeric films fabricated from ionically self-assembled monolayers (ISAMs) spontaneously from in a noncentrosymmetric structure requisite for a nonzero second order nonlinear optical (NLO) susceptibility, (chi) ⁽²), without the need for electric field poling. ISAM NLO films exhibit excellent long-term temporal stability of (chi) ⁽²), having shown no decay over a period of nearly three years. They are also remarkably stable at elevated temperatures. While (chi) ⁽²) decreases by 20 percent as the temperature is raised to 150 degrees C, total recovery of the susceptibility is observed upon cooling, demonstrating that the decrease is not due to an irreversible randomization of the chromophore alignment. The thickness, orientational order, and NLO response are found to be strongly dependent on the pH and ionic strength of the solutions form which the films are deposited. The largest (chi) ⁽²) values are observed in films with the smallest bilayer thickness. This suggests that polar orientation is obtained primarily at the interfaces between adjacent layers rather than throughout a full monolayer.

Alternating polyelectrolyte deposition (APD) is a room temperature process that can produce noncentrosymmetric ordered films of nonlinear optical polymers (NLOP). Previous studies using a stilbazolium-substituted polyepichlorohydrin (SPECH) as the NLO-active polycation exhibited a saturation of the SHG signal independent of the number of deposited layers. This saturation effect was thought to be due a change in the charge density in the outermost layers. The charge density is the main driving force for chromophore alignment. In this study, NLO-inactive spacer layers were used to regenerate the charge density before continuing with deposition of NLO-active layers. The overall SHG signal from these 'multi-deck sandwich' films was higher than previously obtainable with SPECH as the NLO-active material. The surface morphology, roughness, and film thickness have been characterized by Tapping Mode Atomic Force Microscopy.

Optical limiting effect has been investigated in polyimide- fullerene and polyimide-dye-fullerene systems. The second harmonic of a pulsed Nd:YAG laser was applied as an irradiation source. The laser radiation was attenuated at least by an order of magnitude. When fullerenes and dye were simultaneously introduced in polyimide, the most optical limiting effect was observed. It was established the fullerene-doped polyimide systems could be applied for limiting power to more than 4 J cm^-2.

Reverse saturable absorption by C₆₀ and C₇₀ fullerenes-doped 2-cyclooctylamino-5-nitropyridine (COANP)- toluene solutions and COANP-polyimide films has been investigated. The fullerene concentration was varied from 0.5 to 5 wt percent. The second harmonic of a pulsed Nd:YAG laser of 532 nm wavelength, overlapping an absorption band of fullerene-doped COANP, was used. For both COANP-fullerene solution and thin films nonlinear transmission was observed. Laser radiation attenuation exceeded at least by a factor of 6-7. The nature of optical limiting effect revealed in COANP-C₇₀ system is discussed. It was established that the COANP-fullerene compounds could be applied for limiting power of about 5-6 J cm^-2.

Quantum chemical ab initio calculations along with full geometry optimizations of Disperse Orange 3 (DO3), molecule in the ground state of the trans and cis conformations and carbazole (Cz), phenylenediamine molecules were performed applying the method of density functional theory (DFT). The obtained geometry of the ground state was used as initial one for the performed calculation with the optimization in the first excited state. The excited state has been investigated applying ab initio configuration interaction single-excitation molecular. Three variable light induced molecular machine was designed based on results of the obtained internal molecular motions during excitation of the DO3 molecule and the full geometry optimization was performed applying Hartree-Fock method for this device. The ZINDO method was applied performing the spectra calculations of the isolated photoactive molecules and the supermolecule- device. Several molecular logical machines are designed.

Two photon absorption (TPA) with the TPA coefficient (beta) equals 0.59 cm/MW was obtained for polyphenylquinoxaline film by using Z-scan technique at 532 nm wavelength of a passively mode-locked Nd:YAG laser. This was, to our knowledge, the largest ultrafast TPA in conjugated polymers ever reported. And it was shown that the corresponding imaginary part of the third order optical susceptibility (chi) ⁽³) shared an equivalent importance with the real part. The resultant value of (chi) ⁽³), 2.4 X 10^-10 esu, was in a good agreement with the reported value.

The potential development of optoelectronic devices based on the NLO response of organic molecules has aroused much recent interest. The influence of the molecular interactions on their NLO properties is important to both basic and application study. The dye rhodamine B can form different protonation and aggregation states by changing the bulk pH, which is revealed by the UV-visible absorption spectra and the fluorescence emissions spectra. Here we also use the hyper-Rayleigh scattering (HRS) technique to probe more detailed information about the protonated forms and aggregates. Because rhodamine dye is an ionic compound, the classical technique electric-field-induced second-harmonic generation can not be used to get the first-order hyperpolarizability (beta) . Our further studies show that rhodamine has strong multi-photon fluorescence emission under the radiation of 1064nm and it overlaps the HRS signal at 532 nm. The concentration dependence of the HRS intensity shows that only in the very low concentration range the HRS signal increases linearly with the increasing concentration. In the higher range, the signal deviates from the line on the below side, which may arise for the linear absorption of the signal at 532 nm, nonlinear absorption of the incident laser beam, the intermolecular effect and distortion of the incident laser at high concentration.