This PDF file contains the front matter associated with SPIE Proceedings Volume 7049, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

We measure two-photon absorption (2PA) spectra and 2PA cross sections in an assortment of different molecules such as substituted diphenylaminostilbenes and push-pull porphyrins using femtosecond fluorescence excitation method. The peak 2PA cross section in the lowest dipole-allowed transition is well described by two level model and can be estimated with better than 50% absolute accuracy from the value of transition dipole moment and permanent dipole moment difference between ground and excited state that we obtain solely from linear spectroscopic measurements. 2PA peaks corresponding to transition to higher energy states are quantitative described by three-level model. We find also that larger value of the permanent dipole moment difference correlates with a smaller value of permanent dipole moment in the electronic ground state.

The developments in porphyrin chemistry over the last decades give great advantages for the practical use of porphyrin-based compounds. The properties of these compounds can be systematically tuned by rational utilization of substituents on meso- and/or β-positions as well as by using different metal atoms in the center of the tetrapyrrole macrocycle. Recently we prepared novel mono- and bis-functionalized cycloketo-porphyrins (CKPors). In this work the results of detailed spectroscopic investigations of these compounds are presented. It was found that a seven-membered ketone exocycle remarkably influences the photophysical properties of the CKPor systems. For mono-functionalized CKPors it results in strongly enhanced probability of intersystem crossing S₁ → T₁ with an ISC quantum yield up to 90%. Moreover, the absorption of all CKPors undergoes a bathochromic shift and the Q-bands extinction is above two times higher compared to that of H₂TPP, what makes these compounds promising candidates for use as photosensitizers in photodynamic therapy of tumors. For the first time two NH-tautomers of nonsymmetrical CKPors were experimentally resolved at room temperature using optical spectroscopic methods. It was found that the concentration of tautomer A with a lower frequency of the S_0,0 → S_1,0 transition is higher than that one of tautomer B at room temperature, and becomes dominant with cooling down. In contrast - and as it is expected - only one optical active species was observed for non-symmetrical CKPor with a central Zn(II) atom as well as for symmetrical bis-CKPor.

There has been much interest in the development of two-photon absorbing materials and many efforts to understand the nonlinear absorption properties of these dyes. We have recently explored a new type of two photon absorbing dye containing a platinum center with ligands that vary in length that contain electron withdrawing benzothiazole. With increased π-π* conjugation we expect to observe a red shift in the absorption properties of the material. We have investigated the photophysical properties of the platinum chromophores using a variety of experimental techniques. Previously we determined that the singlet and triplet excited states are responsible for nearly all of the nonlinearity in the nanosecond regime accept the two photon mechanism that is primarily used for excitation. Therefore we would like to tune the photophysical properties of both the singlet and triplet excited state in these materials. To our surprise we found there is quite a bit of red shifting due to a metal-to-ligand charge transfer from the platinum to the ligand rather than the expected shifting due to increased π-π* conjugation. However, with increased ligand length the chromophore does take on more π-π* character.

To learn about excited state geometry in biphenyl-containing platinum acetylides, we synthesized a series of compounds that have biphenyl ligands. The ligands consisted of biphenyl(I), the hindered 2'-methyl biphenyl(III) and planar fluorenyl(IV) groups. We also synthesized a "half" complex(II) consisting of one ligand attached to the platinum atom. The optical properties of these compounds were measured by ground state absorption, phosphorescence, ultrafast transient absorption and nanosecond transient absorption spectroscopy. DFT calculations were performed to determine the ground state and triplet state geometries and the lowest triplet energy. TDDFT calculations were performed to determine singlet excited state energies. Compared to the reference compound I, ground state spectra show a blue shift in II and III and red shift in IV, showing the singlet energy is sensitive to conjugation and biphenyl twist angle. Comparison of the phosphorescence spectra of I and II shows the triplet exciton is confined to one ligand. The time behavior of the ultrafast excited state absorption spectrum of I shows a red shift within 1 ps from the initial spectrum. This behavior is not seen in IV. The different behavior suggests formation of the triplet state of I is accompanied by conversion from a non-planar to a planar conformation while IV retains a planar conformation.

Hyper-Rayleigh scattering (HRS) is the only second-order nonlinear optical (NLO) technique allowed in an isotropic solution. Being an even-order technique, it is sensitive to (non-centro)symmetry. Therefore, HRS is a unique tool to determine solution-phase structure, both in a qualitative and a quantitative way. Examples are presented of the elucidation of the actual D2d octopolar structure of highly symmetric, yet non-centrosymmetric chromophores and of the determination of the value for the opening angle of a chromophore-functionalized alkynyl-calix[4]arene cavity.

We report on a pump-probe photothermal lens experiment aimed for the measurement of thermal diffusivity coefficient of organic samples in the CW regime. We show that when the probe beam is collimated and the pump beam is focused the time dependence of the signal does not depend on the sample position. This effect allows simple determination of the thermal diffusivity coefficient and its effective calibration using reference samples. We use this method to determine the thermal diffusivity of distilled water, methanol, chloroform, nitrobenzene and other organic solvents.

Optical properties such as index of refraction and optical absorption of many chromophore-doped polymers are sensitive to the physical and chemical environment to which the polymers are exposed. Detection sensitivity is further enhanced by optical micro-resonator structures such as waveguide micro-ring resonator and fiber Bragg gratings. Chromophore-doped polymers also offer some desirable flexibility in device fabrication. Ultraviolet light and electron beam can reduce the index of refraction of the polymer. The photobleaching and electron beam bleaching methods form optical waveguides in a single fabrication step and do not involve solvents or wet chemicals, and can be applied to polymers that are not compatible with other waveguide fabrication techniques. This Paper provides an overview of the basic principles and designs of such sensors. A chemical sensor to detect trace explosives and a broadband fiber optic electric-field sensor are presented as practical examples.

In the optical materials, the remarkable change of refractive index due to optical intensity is important for making photo-devices such as optical switching, memory and logic circuits. The optical waveguide consisted of poly (3-hexylthiophene)/polymethylmethacrylate (P3HT/PMMA) composite film and a prism was fabricated to find out its optical bistable characteristics. The refractive index of P3HT/PMMA composite film measured by ellipsometry was 1.48. Moreover, the refractive indexes of the atmosphere and the prism were 1.00 and 1.52 respectively. Therefore, the fabricated waveguide satisfied the condition of the quasi-waveguide. For improving the nonlinear optical characteristic of the composite film, P3HT/PMMA composite film was exposed to organic gas for 25 hrs. As the laser light source, Nd:YAG laser (wavelength: 1064 nm, pulse width: 5 ns, repetition frequency: 10 Hz) was adopted for optical bistability and third-harmonic intensity measurement. The input light intensity dependences of the optical bistable characteristics of the quasi-waveguide consisting of the P3HT/PMMA composite thin film, which was exposed to organic gas for 25 hrs were investigated. The measured optical bistability displaced excellent stability and hysteresis characteristics. It suggests that the composite film exposed to organic gas has larger grain size, better molecular orientation, homogeneous bulk and smooth surface than that of before organic gas treatment.

Surface relief structures are optically inscribed onto azobenzene containing thin films. We present a brief review of the technique and results. The films act either as optical waveguides of as substrates upon which thin gold films are deposited to support surface plasmon waves. Multiple gratings are inscribed to act as optical couplers and Bragg gratings. Here, we report on the amplitude and phase changes that occur when the incident light is resonantly coupled into waveguide or surface plasmon modes. We illustrate the method of obtaining the dispersion curve of the device. The effects on amplitude are readily observed in the transmission or reflection spectra. In addition, since the structures can be made such that the resonant TE and TM modes to be well separated, we can measure the phase changes of the transmitted or reflected beams near resonance. A simple device showing polarization to wavelength modulation encoding is presented.

Passive sol-gel materials play an important role in the development of electro-optic(EO) polymer-based modulators, because of their variety of available refractive indices. They can be used to form passive waveguide transitions to minimize coupling loss or as cladding layers for the EO polymer. The demands for these two applications are different. For waveguide transitions the most important factor is the optical loss. Cladding layers should have a relatively high conductivity at elevated temperatures to improve poling efficiency. Both demands are addressed in this study. The synthesis of low loss (down to 0.45 dB/cm) sol-gel materials is shown. Slab waveguides as well as ridge waveguides were fabricated and characterized by liquid prism measurements and cut-back loss measurements, respectively. For use in cladding layers surrounding the EO polymer, materials with higher conductivity were developed. The conductivity of the materials was increased, (3•10^-9 S/m) through the use of a silane, which allows in situ formation of proton donating functionalities. All developed materials can be used as solvent free resins, which enables classic photolithography as well as patterning by UV-imprinting. The available refractive index range (at 1.55 μm) is from 1.495 to 1.562.

Poly(methyl methacrylate-co-9-anthrylmethyl methacrylate) (PMMA-AMA) LP-136 with various AMA contents was prepared. The polymer was modified via Diels-Alder (D-A) type "click chemistry". In one approach, the side-chain was grafted stepwise with maleimide-containing chromophore AJL-04 followed with N-phenylmaleimide (PI) to form LP-160. LP-160 was doped with 30 wt % of chromophore AJLS-102 to give electro-optic (EO) core polymer AJ-415. In the other approach, all the pending AMA groups were modified with PI in one step to yield LP-165. Doping 33.7 wt % AJLS-102 in LP-165 gives another core polymer AJ-416. The EO and material properties of both polymers were systematically studied. Via careful selection of bottom and top cladding materials with proper optical and electrical properties, Mach-Zehnder type modulators were fabricated based on both core materials. At the operational wavelength of 1550 nm, modulator with AJ-415 core has half-wave driving voltage (V_π) of 0.95 V and insertion loss of 19.1 dB, while the best results from modulators with AJ-416 core are 0.75 V of V_π and 17.1 dB of insertion loss. AJ-416 also has the advantage over AJ-415 for building EO modulator with better processibility and long-term stability.

The fluorescence of chromophores embedded in a photonic crystal is inhibited by the presence of a photonic pseudo-gap. We present the influence of such an incomplete bandgap on the emission and energy transfer by studying the steady-state and time-resolved emission properties of both a donor and an acceptor fluorophore in a self-assembled photonic crystal. Our results clearly show an inhibition of the donor emission and a concomitant enhancement of the acceptor emission, indicating improved energy transfer from donor to acceptor. This is explained by the decreased number of available photonic modes for radiative decay for the donor in a suitable engineered photonic crystal with respect to in the effective homogeneous medium.

We report a technique for embedding submicrometer-scale polymer defects in the interior of self-organized two-dimensional photonic crystals by controlled two-photon induced polymerization. They demonstrate a rapid and flexible technique for optical fabrication by creating polymer features in registration with a photonic crystal. Polymer features were embedded in individual pores with a diameter of 100 nm by controlled photopolymerization under confocal optical microscopy. Spectrum measurements confirm that the photonic stop band limits the light propagation of the emission from the embedded polymer structures.

Gold clusters with the sizes close to the Fermi wavelength of electron shows interesting quantum size effects. Linear and nonlinear optical properties show dramatic trends when the sizes of clusters are in the range of quantum confinement. We have investigated the size dependence of the non-linear optical property of two-photon absorption (TPA) cross-sections of the gold clusters. Absolute TPA cross-sections are measured by a combination of one and two-photon excited fluorescence upconversion measurements. Large cross-sections and abrupt changes in the trend of cross-sections are observed in the size-dependence when size is reduced from nanoparticles to cluster. The results can be attributed to the appearance of quantum confinement in these monolayer protected gold clusters.

Holographic polymerization (H-P) has been used to fabricate polymer-dispersed liquid crystals, block copolymers and pattern inert nanoparticles. In this article, one-dimensional grating structures of Norland resin and a polymer blend were achieved using the H-P technique. A reflection grating structure known as a Bragg reflector (BR) was fabricated. The hierarchical structure and morphology of the BR were studied using synchrotron X-ray, polarized light microscopy and transmission electron microscopy. The structure of the BR containing a polymer blend displayed lamellae structures formed with periodicity of 200 nm. Polycaprolactone and Poly(L-lactide) crystals were found to be confined in ~ 60 nm thick layers in the BR. The polymer chains tended to orient themselves parallel to the grating when the two polymers where blended together. The phase separation and structure of the polymer blend inside the H-P grating could be of great interest for multifunctional optical sensors or devices.

We present the design, fabrication and characterization of the optical properties of one-dimensional metal-organic photonic bandgaps (MO-PBGs) composed of a tetraphenyldiaminobiphenyl-based polymer and ultrathin electrically continuous Cu layers. The fabricated MO-PBGs achieve a peak transmission of around 44% at 620 nm combined with very large spectral, around 120 nm FWHM, and angular, more than 120° field-of-view, bandwidths. Using 140 fs pulses at various wavelengths we have found up to 10 × enhancements in the nonlinear optical (NLO) properties of the MO-PBGs when compared with the NLO response of ultrathin electrically continuous Cu layers.

Multiple users could be multiplexed into a single Coarse Wavelength Division Multiplexing (CWDM) channel of metropolitan area networks using an Optical Code Division Multiple Access (OCDMA) scheme increasing the total number of users of the system. Thermally tunable holographic filters operated using an edge illuminated transmission hologram configuration, can provide a compact and tunable solution for this application. The filters are realized by a thick unslanted grating. The gratings are recorded in PQ (phenanthrenequinone)-doped PMMA (poly methylmethacrylate) photopolymer substrate in a holographic setup. The gratings are designed to filter light from the propagation direction for specific segments of a CWDM channel. The filters can be thermally tuned using thermo-electric cooler plates to change the period of the grating. In this paper we present the construction and performance characteristics of these filters.

The third-order nonlinear optical properties of regioregular poly(3-hexylthiophene) (RR-P3HT) thin films prepared on fused glass substrate were evaluated. The surface modification by hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (ODTS) was performed on the glass substrate to form self-assembled monolayer (SAM) layers. The formation of SAM layers on the glass substrate increase the contact angle of the solution and the optical property of the RR-P3HT thin films is enhanced due to the excellent orientation and alignment of the thin film. The π-conjugated macromolecule thin films can be prepared by spin-coating and drop-casting methods and the structure and orientation alignment of thin films can be controlled by the solution processing and deposition techniques. The nonlinear optical property, third-harmonic generation of RR-P3HT thin films has been evaluated by Maker-fringe method. The third-order nonlinear optical susceptibilities χ⁽³⁾ (-3ω; ω, ω, ω) of drop-cast RR-P3HT thin films on quartz glass substrate were estimated from optical third-harmonics (TH) intensity measurement. An Nd:YAG laser with a wavelength of 1064 nm, pulse width of 5 ns and a repetition frequency of 10 Hz was used to evaluate the TH intensity. The effect of surface modification of quartz glass substrate by HMDS and ODTS on the RR-P3HT film structure was also investigated. The orientation alignment and crystallinity of the RR-P3HT thin films were evaluated using X-ray diffraction (XRD) and UV-vis absorption spectra. The UV-vis and XRD profile reveals the better orientation and crystallinity of the RR-P3HT thin film after surface modification by HMDS and ODTS. Moreover the incident angle dependences of third harmonic (TH) intensity was measured and the TH intensity of RR-P3HT thin film prepared on glass substrate with SAM layer was found to higher than that of non-treated substrate. The SAM layers significantly enhances the optical property of the material and the third-order nonlinear optical susceptibility (χ⁽³⁾) of RR-P3HT thin films on quartz glass surface modified by ODTS is 1.90 × 10^-8 esu. The third-order nonlinear optical susceptibility (χ⁽³⁾) of RR-P3HT thin film was found to higher than poly(p-phenylenevinylene) (PPV).

The refractive index is a key characteristic of polymer materials in optical applications. For organic polymers, typical refractive indices are in the range of 1.35 to 1.65. Extending the refractive index beyond the limits is of fundamental scientific interest and would enhance the utility of polymers in many applications. Polymeric thin films fabricated by plasma enhanced chemical vapor deposition (PECVD) have been investigated in the fields of electronics and optics and their utility is becoming more widespread in a variety of applications. Outstanding attributes of the PECVD photonic films include a smooth surface, dense crosslinking structure, robustness, environmental resistance, optical transparency in either visible or IR regions, and good adhesion to many optical window and substrate materials. In recent years, our laboratory has fabricated novel polymer optical coatings and films by PECVD. One focus of this research has been to expand the achievable maximum refractive index. This goal has been sought using two approaches including increasing the conjugation and crosslinking of chemical moieties of the bulk film and incorporation of metal ions into the structure. The techniques of XPS, FTIR, HRSEM, and ellipsometry were used to characterize both the optical properties and the chemical structure of plasma polymerized benzene, ferrocene, and metal-phthalocyanine thin films. The structure-property relationship and the effect of PECVD processing conditions are also discussed in this presentation.

It was studied the influence of F, Sbt, Sil, Sbo monomer and homodimer Dst-5, Dst-10, Dbt-5, Dbt-10, Dil-10, Dbo-10 styryl dyes on blood erythrocytes of white rats. It was shown that the homodimer styryl dyes Dst-5, Dbt-5 and Dbo-10 decrease the erythrocytes quantity by 1.5-2 times more as compared with monomer dyes Sbt and Sbo. The main cause of dyes different action is the different oxidation degree of intracellular hemoglobin evoked by these dyes. It was established that the observed effects was connected with different penetration of these dyes through membrane of erythrocytes and with interaction of these dyes with albumin localized in membranes of cells.

We present a detailed study of the local environmental sensitivity of the commercially available laser dye, Styryl-9M. Positions of the one-photon and two-photon absorption maxima and two-photon absorption minimum of the dye are sensitive to the solvent polarity. In aqueous solution its absorption and fluorescence spectra consist of two peaks whose relative strength depend on the surrounding pH-s. The dye shows one of the highest two-photon absorption cross sections, 700-1300 GM at the peak, among widely available compounds. Comparison of the linear and nonlinear properties shows that its maximum cross section can be described by an effective two-level model. Based on the properties of Styryl-9M we propose a new method of sensing local environment polarity in solutions and biological phantoms. We show that the dye is a promising candidate for two-photon biological imaging and microscopy.

We report on Fourier transform spectra of deuterated proteins: Bovine Serum Albumin, Leptin, Insulin-like Growth Factor II, monoclonal antibody to ovarian cancer antigen CA125 and Osteopontin. The spectra exhibit changes in the relative amplitude and spectral width of certain peaks. New peaks not present in the non-deuterated sample are also observed. Ways for improving the deuteration of proteins by varying the temperature and dilution time are discussed. We propose the use of deuterated proteins to increase the sensitivity of immunoassays aimed for early diagnostic of diseases most notably cancer.