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Measurement of the Stark effect of the 856-nm transition from the 6s5d1D2 metastable state to the 5d6p1D2 level in Ba is reported. High-resolution atomic-beam laser spectroscopy was performed and Stark shifts and splittings of 138Ba and 136Ba were measured under various electric fields. The tensor polarizability of the upper level 5d6p1D2 and scalar polarizability of the 6s5d1D2–5d6p1D2 transition were found to be much larger than those of other levels of the 5d6p configuration. The observed large electric polarizabilities were reasonable compared with recent results on the related forbidden transition of 6s5d1D2–5d21D2, which further indicates strong mixing between the upper close-lying levels of 5d6p1D2 and 5d21D2. [ABSTRACT FROM AUTHOR]

A microperiodic structure composed of polymer and liquid crystal (LC) phases, called holographic polymer dispersed LC, is fabricated by a photo-induced phase separation technique using LC composites with different physical properties, such as refractive indices and clearing points. Effects of thermal modulation on diffraction properties of LC composite gratings are experimentally investigated in the viewpoints of polarization and temperature dependences. The diffractions based on the change of refractive index induced by the nematic--isotropic transition of LCs with the increase of temperature are applied for a holographic image reconstruction. [c] 2010 Optical Society of America OCIS codes: 090.2900, 160.3710, 160.5470.

The surface plasmon spectra (SPR) spectra of silver nanoparticles that were fabricated on a thermochromatic metal oxide, VO2, that exhibits a reversible metal-semiconductor phase transition at nearly 56 degrees Celsius is discussed. Further than SPR band the spectral line shape of silver particles were dominated by the imaginary part of the dielectric function of VO2.

We have studied the diffuse reflection properties of ceramics in the presence of dielectric thin films on the surface. A simple optical model was proposed in which interference effects in a thin film were considered for light scattered out of a ceramic in various directions. Measurements were performed on angle-resolved reflection spectra of a thin-film-coated alumina ceramic in the case of normal incidence. They showed that the presence of the thin film on the ceramic's surface modified the angular distributions of scattered radiation from that of a bare ceramic, which suggested a way to tailor the scattering properties of a diffuse reflector as needed. OCIS codes: 120.5700, 290.1990, 310.1620, 230.0250.

Spectral selective radiating material (SSRM) such as a SiO film deposited on metallic substrate can be cooled lower than the ambient temperature due to its high IR emission in the spectral region of the atmospheric window under clear sky conditions. In this paper we propose a new stacked SSRM consisting of SiO film and [V.sub.1-x][W.sub.x][O.sub.2] thermochromic film to stabilize the surface temperature of the sky radiator. The transition temperature from metallic to semiconductor phase of [V.sub.1-x][W.sub.x][O.sub.2] thermochromic film can be adjusted to a temperature near ambient by the control of the doping level of x. The radiative cooling of the new SSRM was simulated using the optical constants of SiO and [V.sub.1-x][W.sub.x][O.sub.2] obtained by optical measurements. The results reveal that the newly designed SSRM can attain a stable surface temperature determined by the transition temperature of the [V.sub.1-x][W.sub.x][O.sub.2] film.

The spectral complex optical constants in the visible and the near-infrared region of V[O.sub.2] and [V.sub.1-x][W.sub.x][O.sub.2] films deposited on glass substrates were determined from observed reflectance and transmittance spectra for which the least-squares method was used. In the metallic phase, the optical properties were characterized by the Drude model in wavelength regions longer than 750 nm.

Thermal tuning of the localized surface plasmon resonance (LSPR) of Ag nanoparticles on a thermochromic thin film of VO2 was studied experimentally. The tuning is strongly temperature dependent and thermally reversible. The LSPR wavelength λSPR shifts to the blue with increasing temperature from 30 to 80 °C, and shifts back to the red as temperature decreases. A smart tuning is achievable on condition that the temperature is controlled in a stepwise manner. The tunable wavelength range depends on the particle size or the mass thickness of the metal nanoparticle film. Further, the tunability was found to be enhanced significantly when a layer of TiO2 was introduced to overcoat the Ag nanoparticles, yielding a marked sensitivity factor ΔλSPR/Δn, of as large as 480 nm per refractive index unit (n) at the semiconductor phase of VO2. [ABSTRACT FROM AUTHOR]

We report on the utilization of localized surface plasmon resonance (LSPR) of Ag nanoparticles to tailor the optical properties of VO2 thin film. Interaction of nano-Ag with incident light yields a salient absorption band in the visible-near IR region and modifies the spectrum of VO2 locally. The wavelength of modification occurs in a limited spectral region rather than affects the full spectrum. The wavelength of modification shows a strong dependence on the metal nanoparticle size and shifts toward the red as the particle size or the mass thickness of nano-Ag increases. Also, we found that the wavelength can be shifted into the IR further by introducing a thin layer of TiO2 onto the nano-Ag. Interestingly, with the help of LSPR effects the VO2 film exhibits an anomalous thermochromic behavior in the modification wavelength region, which may be useful in optical switching applications. [ABSTRACT FROM AUTHOR]

High-resolution spectra from 20 to 200 cm to the -1 for temperatures from 10 to 300 K give interference fringes that cannot be fitted by previous analysis in terms of four Lorentz oscillators. Parameters in the theory are revised to give a better fit both to the far IR and to the reststrahlen spectra.

The experimental studies of thermal tuning of the localized surface plasmon resonance (LSPR) of Ag nanoparticles on a thermochromic thin film of V[O.sub.2] is reported. The tunable wavelength range has depended on the particle size or the mass thickness of the metal nanoparticle film and the tunability is enhanced by introducing a layer of Ti[O.sub.2] to overcoat the Ag nanoparticles.

The use of localized surface plasmon resonance (LSPR) of Ag nanoparticles to tailor the optical properties of V[O.sub.2] thin film is reported. The V[O.sub.2] film is influenced by LSPR and has exhibited an anomalous thermochromic behavior in the modification wavelength region that might find use in optical switching applications.