This PDF file contains the front matter associated with SPIE Proceedings Volume 10360, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

Purely organic materials with negative and near-zero dielectric permittivity can be easily fabricated, and propa- gation of surface polaritons at the material/air interface was demonstrated. Here we develop a mean-…eld theory of nonlinear light-induced "plasmonic" properties of organic materials. The theory describes both a red shift of the resonance frequency of isolated molecules, according to the Clausius-Mossotti Lorentz-Lorentz mecha- nism, and the wide variations of their spectra related to the aggregation of molecules into J- or H-aggregates. The bistable response of organic materials in the condensed phase has been demonstrated using the electron- vibrational model. We predict the generation of the switching waves, or kinks in the bistable organic thin …lms that enable us to observe a bistable behaviour of the surface polaritons at the organic thin …lm/dielectric inter- face under the laser irradiation. We present the alternating-sign dependence of the switching wave velocity on pump intensity and discuss a possibility of controlling the polariton propagation by switching waves.

The photophysical properties of cyclometallated iridium compounds are beneficial for nonlinear optical (NLO) applications, such as the design of reverse saturable absorption (RSA) materials. We report on the NLO characterization of a family of compounds of the form [Ir(pbt)2(LX)], where pbt is 2-phenylbenzothiazole and LX is a beta-diketonate ligand. In particular, we investigate the effects of trifluoromethylation on compound solubility and photophysics compared to the parent acetylacetonate (acac) version. The NLO properties, such as the singlet and triplet excited-state cross sections, of these compounds were measured using the Z-scan technique. The excited-state lifetimes were determined from visible transient absorption spectroscopy.

Effect of ferroelectricity on the photorefractive effect of ferroelectric liquid crystal blends was investigated. The photorefractive effect of ferroelectric liquid crystal blends strongly depend on the ferroelectricity of the blend. We have prepared a series of ferroelectric liquid crystal blends that contains several concentrations of a chiral compound while keeping a constant concentration of a photoconductive moiety. The photorefractive properties of the ferroelectric liquid crystal blends were discussed with relations to the ferroelectric properties of the blends.

Here, we introduce a paradigm change in phase matching strategy and demonstrate how integrated waveguide optics can be used for wave mixing with large wavelength mismatch.

Many materials exhibit nonlinear refraction (NLR) and absorption (NLA) that has multifaceted temporal dynamics. As a result, measurements at one laser pulse width may not be fully predictive of the behavior at other pulse widths. We have recently developed a method, Nonlinear Beam Deflection, (BD) that allows sensitive time-resolved measurement of nonlinear refraction (NLR) and absorption (NLA) by using an excitation beam to create an index gradient deflecting a probe beam onto a quad-cell detector. The method has a demonstrated sensitivity to induced phase changes as small as 1/20,000 of a wavelength, which is sensitive enough to measure NLR in gases. By changing the relative polarization of the beams we can separate the bound-electronic response from the slower and different-symmetry nuclear contributions. In gases and liquids where reorientational nonlinearities are important, measurements at the magic angle allow isolation of the ultrafast nonlinearities. In isotropic solids the bound-electronic symmetry dictates a ratio of 1/3 for parallel to perpendicular polarizations which measurements confirm. This method also allows for measurements of nonlinearities using very different wavelengths for the excitation and probe. We have used this method to characterize the impulse response function for third-order nonlinearities in many transparent organic solvents. This allows accurate prediction of the nonlinear refraction for any pulse width longer than that used for the BD characterization. The method proves to be very useful in organic materials that may show strong nonlinear absorption, as it is able to resolve NLR in the presence of strong NLA better than other methods, such as Z-scan.

Two dimensional (2D) graphene and transition metal dichalcogenides are an emerging class of extremely interesting materials showing unique physical properties, such as large third-order optical nonlinearity, offering potential applications in optical limiting. Here we report the optical limiting properties of Titanium disufide (TiS₂), and Graphene sheets measured using open aperture and photo-acoustic z-scan techniques. Our best results were observed in TiS₂ Sheets, yielding an optical limiting of 77% at an irradiance of 0.713 GW/cm²with 2PA and 3PA absorption coefficient to be 80cm/GW and 2000 cm³/GW² respectively.Also, TiS₂ sheets show improved shelf life and stability upon irradiation with higher laser powers. This demonstrates the feasibility of using them as a potential candidate for optical limiting applications.

In recent years, the ability to pattern large areas at the micro- and nano-scale with stimuli-responsive materials has opened the opportunity to engineer surface structures and trigger peculiar properties such as complex optical functionalities or surface properties by laser-matter interactions. The use of light-sensitive materials, such as azobenzene compounds, can open the opportunity to active manipulate in terms of morphology, physical and mechanical properties a pre-patterned architectures, which are intrinsically static once fabricated. We employ azopolymers, in which the rapid and reversible photoisomerization reaction of azobenzene molecules can actuate mass transport phenomena typically parallel to the light polarization. The azopolymeric film is patterned by soft-imprinting as an array of micro-holes showing a well-defined isotropic round pores. Upon a linearly polarized illumination (365 nm, 150 W/cm2), we observe a deformation of the initial holes along the polarization direction, in such a way that the circular pores are transformed into long closed slits. A rotation of the polarization by 90° triggers a reconfiguration of the pristine round shape, with a good degree of control of the photo-induced pore reshaping. Due to the polarized-directionality of the photo-manipulation we demonstrate the possibility to tune the pristine morphology and properties along specific directions, providing a smart engineered platform with different reshaped micro-patterns. The light-induced contraction and expansion reshaping strategy of a porous polymeric structures shows exciting potential for a number of applications including microfluidics, lithography and tissue engineering. Tuning cells behavior in response to material manipulation cues is a promising goal in biology

Laser oscillations need a combination of gain media and optical cavities. We have used as the gain media crystals of thiophene/phenylene co-oligomers (TPCOs) that are composed of inline thiophene and benzene rings, and combined them with diffraction gratings acting as the optical cavities. We have fabricated these diffraction gratings on substrates as an external cavity. Recently, we have directly engraved one-dimensional (1D) diffraction gratings on the surface of TPCO crystals by using focused ion beam (FIB) lithography. We regarded these diffraction gratings as a built-in cavity, and expected to be effective for producing narrowed emission peaks. However, the engraved parts of the crystals were quenched because the ion beam damaged the molecules. Engraving the diffraction gratings with a short period that is comparable in size to the beam spot caused weak emissions from the crystal. In the present studies, we tried to keep wide unprocessed parts on the TPCO crystals with the FIB lithography. To this end, we fabricated diffraction gratings having a long period on the crystals. We chose one of the TPCOs that shows emission maxima at around 605 and 650 nm. We laminated vapor-phase-grown crystals on substrates. We engraved the equally-spaced 300 grooves with a period of 501 nm by precisely controlling FIB process conditions. We observed the emissions perpendicular to the grating grooves as well as parallel to the crystal surface under ultraviolet light illumination from a mercury lamp. We succeeded in observing a narrowed peak at 662 nm with the crystal with the 1D diffraction grating.

This paper presents the experiments on photoanisotropic organic media films based on the composition of the azodye and polymer containing different polyelectrolytes. As a part of an experiment to strengthen the cohesion of the matrix macromolecules, we individually added to the test compositions polyelectrolytes with variations of quantity and with the different nature. The kinetic curves of the inducing photoanisotropy in the polarization-sensitive films are shown. The addition of the electrolyte to this type of materials contributes to an early manifestation of vector polyphotochromic effect at low exposures, which in turn is a sign of improved photoanisotropic properties as this effect appears exclusively in high-performance polarization-sensitive materials.