This PDF file contains the front matter associated with SPIE Proceedings Volume 6652, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Colloidal photonic crystals, even with low refractive index contrast have a significant effect on the spontaneous emission of internal emitters. This is observed as a modification of the emitters' fluorescence spectrum and as a narrowing and shortening of the decay rate distribution. The decay rates are observed to be nonexponential. This modification was then put to use by fabricating a photonic superlattice, consisting of several photonic crystal slabs deposited on top of each other. Because of the two different photonic bandgaps and effective passband is created between the two and leads to enhancement of emission in this spectral region. These experiments indicate that the threshold for lasing can possibly be lowered by spectrally narrowing the emission of fluorophores infiltrated in suitably engineered self-assembled photonic crystal superlattices, and are therefore important towards the realization of efficient all-optical integrated circuits from functionalized photonic superlattices and heterostructures.

Tunable distributed feedback (DFB) lasing output based on reflection grating configuration instead of the traditional transmission grating type was realized from rhodamine 6G (R6G)-doped ethanol and DCM-doped methanol. Pure gain coupling and additional index coupling were obtained in R6G-doped ethanol and DCM-doped methanol, respectively. The tuning which was independent on the refractive index of the lasing media went through all of the tuning data for the two cases. Dual-peak lasing emissions indicative of the existence of the index grating from the DCM-doped methanol were observed. The interval between the dual peaks increased as the increasing of the pump energy. The effect can be used to estimate the resonant nonlinear refractive index of luminescent materials.

A new optically active photochromic polymethacrylate containing the carbazole moiety, deriving from the chiral monomer (S)-(4-cyanophenyl)-[3-[9-[2-(2-methacryloyloxypropanoyloxy) ethyl]carbazolyl]]diazene [(S)-MLECA] has been prepared and fully characterized with the aim to obtain a multifunctional material which can be considered at the same time as a photonic material for NLO and optical storage, for chiroptical switches, and for photorefractive and photoconductive applications. The complete reversibility of the photoinduced linear birefringence, which is related to fatigue resistance properties seems to be promising for use in optical storage or more generally in the field of photoresponsive systems, and it is not necessary to add dopants in order to observe photoconduction thanks to the presence of the carbazole moiety, which is well known for its hole conducting properties.

We study two-photon absorption (2PA) spectra and absolute 2PA cross sections, as well as fluorescence emission- and excitation spectra along with time resolved fluorescence in a series of new dendrimers, where a single porphyrin/phthalocyanine core is decorated with electron-donating/two-photon absorbing groups. We show that if the combined system has strong π-conjugation/multipolar charge transfer between the core and the attached group(s), then the observed 2PA undergoes cooperative enhancement, where the peak 2PA cross section reaches σ₂=600-2000 GM in a broad transition wavelength region 375-500 nm (laser wavelengths 750-1000 nm). In the systems with less conjugation, the 2PA is less enhanced, and in the limit of very weak conjugation maximum σ₂ remains essentially the sum of the cross sections of the constituents. We show that the conjugation strength correlates with the fluorescence emission properties. In particular, in the strongly linked systems the fluorescence originates mostly from the core porphyrin, whereas in the weakly linked systems the attached chromophores emit independently from the porphyrin. In intermediate conjugation strength case we observe non-exponential fluorescence decays and fluorescence rise times, which indicated Forster resonant energy transfer from the side groups to the core.

We present a two-beam mode-mismatched thermal lens method for pulse excitation aimed for the determination of one- and two-photon absorption coefficient with high sensitivity. In this scheme the excitation beam is focused onto the sample in the presence of a collimated CW probe light of low power. The Z-scan signature is single peaked with a width that depends on the number of photons involved in the absorption. We show that the method is at least two orders of magnitude more sensitive than the well-known open Z-scan transmission method commonly used for multi-photon absorption measurement. Using the proposed method we measure a two photon absorption coefficient for nitrobenzene of β=1.12 10^-10 cm/W for nanosecond pulses and a wavelength of 532 nm.

The good optical properties of PQ (phenanthrenequinone)-doped PMMA (poly methylmethacrylate) and its flexibility to fabricate different substrate configurations make this material attractive for holographic recording. In previous work, filters in PQ/PMMA for Wavelength Division Multiplexing (WDM) and Optical Code Division Multiple Access (OCDMA) were demonstrated and shown to have a 0.03nm/°C thermal tuning range operating near 1550nm. In this paper we investigate the effect of adding silicon dioxide nanoparticles to PQ/PMMA in order to measure the thermal tuning range and investigate the performance of these filters.

We demonstrate fiber optic analog transmission using NTSC-J signal. Multimode fibers with different core diameter ranging from 9 to 500 μm were tested in terms of transmission capability under different degree of misalignments between fibers. Graded index plastic optical fiber made of 500 μm core have shown high potential in stable analog transmission based on effective light coupling and low modal noise impairment.

In this work we report the systematic study of modal analysis in planar organic/inorganic sol-gel waveguides with different compositions, thicknesses, incident wavelengths and substrates. Results from two simulation methods and experimental data are presented and compared.

The mechanisms responsible for a strongly nonlinear dependence on concentration of electro-optic coefficient in poled thin films of a guest - host system, consisting of charge transfer chromophores in a polymer matrix, are in the center of interest since last decade. This effect is probably due to an aggregation of chromophores (dipoles), leading to a cancellation of second-order nonlinear optical susceptibilities. Recently, a direct observation of a process of aggregation of dipoles was reported by Rau et al. An important role for the relaxation is played by an accelerated chromophore aggregation due to heating. We analyze the Monte Carlo kinetics of a poled guest-host system using simulation methods developed for studies of diffraction gratings formation and erasure. Preliminary results indicate a presence in the system of quasi one-dimensional (1D) object - spatial curves - along which the dipoles are aligned. Some of the lines form closed loops, leading to a decrease of nonlinear optical properties. Monte Carlo kinetics of simple processes related to poling of host-guest and purely dipolar systems is presented and discussed.

We designed and synthesized a novel type of a cyclic compound containing azobenzene and binaphthyl moieties. The most significant characteristic of the compound is to possess a reversible change in a dihedral angle of a binaphthyl moiety by means of photoisomerization of the azobenzene moiety. Furthermore, the compound shows change in a twisting motion in a solution, a neat film, and a liquid-crystalline host by alternating irradiation of UV and visible light.

The all-optical poling technique allows writing non-centrosymmetric gratings that are automatically phase-matched for second-harmonic generation by purely optical means. One drawback of all-optical poling in organic materials is the poor stability of the recorded gratings due to thermal and/or photo-induced molecular randomization. Using a two beam technique, we have compared the all-optical poling process in different kinds of polymers with Disperse Red 1 dye: guest-hosts with hydrogen-bond interactions between the guest dye and the host polymer and a side-chain polymer in which the dyes are attached through covalent bonds. We show that in the investigated polymer systems, hydrogen-bonded guest-hosts are capable of surpassing the stability of side-chain polymers.

Progress in the development of a new class of multi-functional polyimides for use in electro-optical devices is reported. These polyimides contain hydroxymethyl-functional side-groups attached to the polymer backbone, allowing for the attachment of a wide variety of molecular species. It is shown that multiple types of organic molecules may be attached to the polymer simultaneously, with a quantitatively controllable distribution, to tailor the physical properties of the material. Methods for cross-linking the polyimides are presented, based on both modification to the backbone and the addition of difunctional additives (such as isocyanates) to solutions of the polymer during spin casting. Processing studies using spectroscopy to track the cross-linking reaction and its effects on organic nonlinear optical materials indicate that the latter method is compatible with poling processes for polymer guest/host systems with high nonlinear optical activities. Further studies using a novel thermomechanical analysis method demonstrate that the cross-linking reactions increase the glass transition temperature and inhibit physical relaxation processes in the cross-linked guest/host films.

Mach-Zehnder optical modulators were fabricated using the CLD and FTC chromophores in polymer-on-silicon optical waveguides. Up to 17 months of oven-ageing stability are reported for the poled polymer films. Modulators containing an FTC-polyimide had the best over all aging performance. To model and extrapolate the ageing data, a relaxation correlation function attributed to A. K. Jonscher was compared to the well-established stretched exponential correlation function. Both models gave a good fit to the data. The Jonscher model predicted a slower relaxation rate in the out years. Analysis showed that collecting data for a longer period relative to the relaxation time was more important for generating useful predictions than the precision with which individual model parameters could be estimated. Thus from a practical standpoint, time-temperature superposition must be assumed in order to generate meaningful predictions. For this purpose, Arrhenius-type expressions were found to relate the model time constants to the ageing temperatures.

In our previous data, following organic gas treatment in 1,2-Dichloroethane vapor, the third order nonlinear susceptibility of a tertiary-butyl vanadylphthalocyanine ((t-Bu)_1.45VOPc)/polymethylmethacrylate (PMMA) composite film was observed to increase markedly, because the phase morphology of the composite film changed from Phase I to II. Therefore, the third order nonlinear optical property of the quasi-waveguide, comprised of composite film, was stronger than that before organic gas treatment. When irradiating the quasi-waveguide treated organic gas for 25 hrs with input laser power intensity, the output power had optical bistability. The optical bistability also displayed excellent stability and effective reproducibility. However, in terms of the input laser power intensity dependences of optical bistability, the switching on-off position shifted with the increase in input laser power intensity. In this study, we adopted a terthiophene(3T)/PMMA and poly(3-hexylthiophene)[P3HT]/PMMA composite films, possessing strong third-order optical nonlinearity, to decrease the change in the on-off position depending on the input laser power intensity. The optical bistability of the optical devices, fabricated using a prism, 3T/PMMA or P3HT/PMMA composite films were investigated. The shift in the on-off position in optical bistability characteristics caused by the refractive index change in the thermal effect was improved by the use of the terthiophene (3T)/PMMA or P3HT/PMMA composite films.

The optical and material properties of AJ309 electro-optic (EO) polymer were systematically studied with the objective to fabricate an optimized integrated device. Both bottom and top cladding materials were developed at Lumera to match the processibility of AJ309, and sustain high poling voltage needed for an effective poling process. A device fabrication process is developed. The degree of crosslinking of the EO polymer before poling is minimized by processing the top clad polymer at room-temperature. The UV-curable top clad has shown no detectable chemical damage to the EO polymer after the deposition process of the top clad, thus maintaining the integrity of the interface between top clad and AJ309 core. A 2.1 cm long active length Mach-Zehnder modulator with low half-wave voltage (V_π) of 1.1 V @1550 nm was fabricated using the AJ309 EO polymer and in-house cladding materials. Other device parameters are also reported.

Structure-property relationships based on experimental as well as theoretical results will be elucidated. For this purpose different dipolar organometallic compounds were synthesized and characterized. The alteration of the donor and acceptor termini in mono- and dinuclear sesquifulvalene complexes results in spectroscopic and even structural modifications. The structural and ¹H NMR spectroscopic changes correlate with the experimentally obtained first hyperpolarizability. The potent electron-donating (D) group [(CpFeCO)₂(μ-CO)(μ-C=CH-)] is combined with different electron-accepting units (A), yielding the push-pull complexes [(CpFeCO)₂(μCO)(μ-C=CH-CH=A)]. The extent of electron delocalization within the π-bridge connecting the donor D and the acceptor A can be monitored by means of ¹H NMR spectroscopy. A correlation between the ³J(H_β-H_γ) coupling constants and the first hyperpolarizability is found, which very much resembles the dependence of the first hyperpolarizability on the bond length alternation. In order to elucidate the dependence of the NLO response on the conformation of triply branched NLOphores, a new series of dendritic D-μ-A structures has been synthesized. A combined approach of experiments and computational predictions was applied both on the dendrimers and on the corresponding single-strand chromophores. These results demonstrate that theoretical calculations are able to reproduce experimental results and show the tendency of the effects due to structural changes

Amorphous, PMMA: DR1: surfactant and PMMA:DR1:TEOS thin films were prepared by dip-coating. All films were calcined at 70 °C for 3 hours. For nanostructured thin films two ionic surfactants were used, Sodium Dodecyl Sulfate (SDS) and Cetyltrimethyl ammonium bromide (CTAB) to obtain two different nanostructures of the PMMA matrix: lamellar, and hexagonal, respectively. X-ray diffraction studies were performed to determine the long-order structure tailored in the films. The measurements of the optical absorption and the second harmonic generation (SHG) intensity were carried out at different orientation arrangements of the chromophores embedded in the films. The chromophore orientation distributions were obtained by means of the corona technique. These distributions depend on the corona poling time. We physically modeled the optical absorption and the second harmonic generation experimental results as function of the corona poling time, employing only one fitting parameter related to the matrix-chromophore interactions. The physical model and the experimental results were in an excellent agreement. The experimental results fitted by the model are shown in plots of order parameter against corona poling time and SHG intensity against corona poling time. The amorphous films provide a larger SHG intensity values than those obtained from the nanostructured films. Thin films with lamellar structure have a SHG intensity bigger than those from hexagonal and PMMA:TEOS thin films.

By utilizing entanglement property of photons the entangled two-photon absorption (ETPA) effect of an organic material, porphyrin dendrimer, is demonstrated through the comparison of the property of entangled photons to the property of quantum-correlated photons. The ETPA showed a cross-section 31 orders of magnitude higher than the cross-section of the classical two-photon absorption (TPA). This high cross-section is comparable to the cross-section of the resonant single-photon absorption. The entangled absorption effect is compared to the correlated TPA effect to determine the degree of correlation between the entangled and quantum correlated photon pairs. The experimental data describe the different degree of correlation of the non-entangled and entangled photon pairs by demonstrating linear and nonlinear relationship of the absorbed photon flux to the input photon flux. The linearity of the ETPA is an interesting quantum effect because the two-photon absorption is an inherently nonlinear process. Virtual state spectroscopy is also demonstrated as a novel spectroscopic method to investigate the properties of the virtual state from non-monotonic behavior of the cross-section which is represented by controlling temporal property of the entanglement. These results from the quantum spectroscopy methods show a unique quantum property which is not feasible to detect using classical methods.

The effects of a complex hybrid conjugation path in linear molecules as an strategy to optimize the intrinsic first hyperpolarizability is investigated. A series of 7 novel chromophores with different hybrid conjugation paths were synthesized and characterized. Hyper-Rayleigh scattering experiments confirm that complex hybrid conjugation paths, including benzene, thiophene and/or thiazole rings in combination with azo- and/or ethenyl-linkages, between a dihydroxyethylamino donor group and different acceptor groups, results in an enhanced intrinsic hyperpolarizability that exceed the apparent limit for two of the chromophores.

In this work, we present a comparative study of the second order nonlinear optical properties of a series of chromophores containing a fused terthiophene, namely dithienothiophene (DTT), as electron relay with either D-π-A or D-π-D substitution patterns. The effect of the acceptor/donor strength and the solvent polarity confirm the possibility of fine-tuning optical non-linearities in the asymmetric samples. The geometrical and electronic properties calculated in solution reveal that push-pull chromophores become highly polarized as the dielectric constant of the solvent increases. Theoretical NLO calculations furthermore reveal a moderate nonlinear optical activity for the symmetric samples.

In this study we report on magnetic orientation of human sperms. Samples were taken from 17 donors. Normal human sperms became oriented with their long axis perpendicular to the magnetic field ( 1 Tesla maximum). Total orientation was achieved with magnetic field at about one Tesla, while for abnormal sperms the magnetic behavior was different. The dependence of the measured degree of orientation on the intensity of the magnetic field was in good agreement with the theoretical equation for the magnetic orientation of diamagnetic substances. As a result for a numerical analysis based on the equation, the anisotropic diamagnetic susceptibility of normal sperm was found to be ▵_χ= 8×10^-20 J/T². The degree of orientation was influenced by the alterations in the shape of the head, body or the tail. It has been suggested that the DNA in the sperm head retain the strong magnetic anisotropy to counter balance the magnetic anisotropy retained by flagellum microtubules. Recent studies demonstrated a well-defined nuclear architecture in human sperm nucleus, where the head morphology has significant correlation with sperm chromatin structure assay SCSA. Then as the methods to evaluate SCSA can be difficult and expensive our simple magnetic orientation technique can be an alternative to diagnose alteration in DNA.

The functional differences of human blood serum albumin in norm and at different patologic process were studied by spectral-luminescent method by comparison of binding constant (K) and concentration of binding sites (N) values of rhodamine B dye with blood serum. It was shown that K and N of rhodamine B dye with blood serum of sick men is decreased as compared to that for healthy men.

A completely passive nonlinear transmission system is constructed using nonlinear absorption materials and azobenzene films. We experimentally demonstrated that in a pump-probe combination, the transmission of a linearly polarized probe beam through a photo-anisotropic material placed between crossed polarizers becomes nonlinear when a nonlinear absorbing medium is placed in the path of the pump beam. The nonlinear transmission of a reverse saturable material serves as pump beam and aligns the azobenzene molecules in a predetermined polarization direction. Thus the transmittance of the probe beam is enhanced at lower input intensities while it becomes clamped at high input intensities. The clamping level and threshold can be controlled by adjusting the concentration of the nonlinear absorbing medium.

We show that hydrogen bonding between azo molecules and polymer host enhances the photoinduced optical anisotropy in azo-containing polymers without sacrificing the ease of processing of conventional guest-host systems. The primary mechanism behind the enhancement is the possibility to use high dye doping levels compared to conventional guest-host systems due to reduced aggregation tendency of the dyes. For Disperse Red 1, the saturated birefringence is enhanced by a factor of 8 due to hydrogen bonding at 30 wt % loading. Moreover, hydrogen bonding reduces the mobility of the guest molecules in the polymer host which improves the temporal stability of the induced birefringence to a level comparable to side-chain polymers.

Organic-inorganic hybrid materials, composed of inorganic oxide structures and interpenetrated cross-linked organic polymers, are promising candidates for electro/optical applications, combining the most important glasslike and polymerlike properties. This is particularly true when large laser power density is used: these materials show high laser damage resistance compared with that of polymeric systems. A deep study of effects and causes of laser damage has never been done, especially for hybrid materials. The mechanisms of optical damage depend on different factors like laser experimental parameters, such as pulse duration, beam size and wavelength, or the microstructural characteristics and defects of the material. Hybrid materials possessing desired shapes and optical and mechanical properties are well synthesized by the sol-gel technique. The use of Glycidoxypropyltrimethoxysilane (GPTMS) allows preparing heterogeneous and resistant materials, with good optical properties. Different sol-gel matrices have been prepared in order to study their laser damage resistance. The possibility of varying the catalysts and precursors or the synthesis protocol allows obtaining materials with similar chemical composition and different microscopical properties. By this way, it is possible to study the laser damage threshold of these samples and to find the way to enhance and optimize the laser damage resistance, useful in non-linear optical devices.

In this contribution we report two-photon excited time-resolved fluorescence and fluorescence anisotropy for several macromolecular systems of different symmetry such as cyclic (single ring) thiophene-based annulenes, triphenylaminecentered branched trimers with pyridine acceptor groups, and linear chromophores possessing high TPA-cross-section. We have compared the ultrafast fluorescence anisotropy dynamics for one- and two-photon excitation routes using timeresolved fluorescence up-conversion setup with femtosecond time resolution. For linear systems the initial anisotropy was found to be about factor 1.4 higher than that for one-photon excitation as predicted by theory. For macromolecular strongly coupled planar systems under two-photon excitations we observed a relatively low initial fluorescence anisotropy (~0.1) and specific femtosecond anisotropy dynamics. Two-photon excited fluorescence anisotropy is strongly correlated to the orientation and value of the transition moment from the excited state to the second and higher lying states and can be used as a direct indicator of strong coupling regime.

Novel optically active multifunctional methacrylic copolymers bearing in the side chain azoaromatic and carbazole groups linked to the main chain with a chiral rigid group of one prevailing absolute configuration have been prepared and characterized in order to observe possible effects on the optical activity of the resulting materials. All the polymeric derivates have good thermal stability with glass transition temperature around 200°C and high decomposition temperatures in the range 280-300°C. Spectroscopic, thermal and chiroptical characterizations indicate the occurrence of dipolar interactions between side chain moieties and the presence of an ordered chiral conformation at least for chain segments of the macromolecules.