A Color Appearance Model Applicable in Mesopic Vision

We propose a color vision model that can be used to predict color appearance in mesopic vision as well as photopic and scotopic vision. It is based on a two-stage model which consists of the cone and opponent stages and it assumes rod intrusion at the opponent stage. The model has the following features to describe the color appearance in mesopic vision. First, it includes a gradual and nonlinear shift in spectral luminous efficiency from V (LD) to V (LD) to cope with the spectral sensitivity difference between photopic and scotopic vision and the nonlinearity of rod influence on the luminance channel. Second, the model assumes decrease of the chromatic component with decreasing illuminance to explain the reduction of saturation at low illuminance levels. Third, it assumes that red/green and yellow/blue components change with illuminance levels independently, thus explaining hue shifts with decreasing illuminance. We applied the model for color appearance simulation of natural scenes in a mesopic visual environment.     

Evanescent tunneling of an effective surface plasmon excited by convection electrons

We introduce the subwavelength transmission of an effective surface plasmon beyond the light zone via the proximity interaction of convection electrons with a metal grating. A comparative analysis of dielectric homogenization and a finite-difference-time-domain simulation shows that out-of-phase-like modes (pi modes) have strong transmission below the cutoff frequency relying on the parametric condition of structural dimension and electronic energy. The synchronous spatial field and charge distribution of the pi mode system confirms the evanescent tunneling effect of the electron-coupled plasmons.     

Evidence for two energy scales in the superconducting state of optimally doped (Bi,Pb)2(Sr,La)2CuO6+delta

We use angle-resolved photoemission spectroscopy to investigate the energy gap(s) in (Bi,Pb)2(Sr,La)2CuO6+delta. We find that the spectral gap has two components in the superconducting state: a superconducting gap and pseudogap. Differences in their momentum and temperature dependence suggest that they represent two separate energy scales. Spectra near the node reveal a sharp peak with a small gap below T(c) that closes at T(c). Near the antinode, spectra are broad with a large energy gap of approximately 40 meV above and below T(c). The latter spectral shape and gap magnitude are almost constant across T(c), indicating that the pseudogap state coexists with the superconducting state below T(c), and it dominates spectra around the antinode. We speculate that the pseudogap state competes with the superconductivity by diminishing spectral weight in antinodal regions, where the superconducting gap is largest.     

Nanoscale retention‐loss dynamics of polycrystalline PbTiO3 nanotubes

We observed the nanoscale retention dynamics of polycrystalline PbTiO₃ nanotubes using piezoresponse force microscopy. We found that the retention loss of the nanodot domains on the nanotubes showed the stretched exponential relaxation behaviors with stretched exponential factor n being less than 1 (0.523 and 0.692), which are similar to the thin films. In addition, the nanodot domains showed a diverse relaxation time constant τ due to different remnant polarization of each dot domains. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effects of in situ plasma treatment on optical and electrical properties of index-matched transparent conducting oxide layer

We investigated the effects of in situ plasma-treatment on optical and electrical properties of index-matched indium tin oxide (IMITO) thin film. To render the IMITO-coated surface hydrophilic and study the optical and electrical characteristics, we performed in situ oxygen plasma post-treatment without breaking vacuum. The 94.6% transmittance in the visible wavelength range (400-700 nm) increased on average to 96.4% and the maximum transmittance reached 98% over a broad wavelength range. The surface roughness and sheet resistance improved from 0.9 nm and 200 Ω/sq to 0.0905 nm and 100 Ω/sq, respectively, by in situ plasma post-treatment. We confirmed by contact angle measurement that the hydrophobic IMITO surface was altered to hydrophilic. The improved optical and electrical characteristics of in situ plasma-treated IMITO makes it adequate for high-resolution liquid crystal on silicon displays.     

Mode-order converter in a multimode waveguide

A novel device that converts the order of modes in an integrated-optic multimode waveguide was proposed and fabricated. The device consists of two mode splitters and tapered waveguides. Its operation at a wavelength of 1.55 microm was confirmed by observation of the output mode profiles. The cross talk measured by an indirect method was >10.2 dB. The excess loss with reference to a straight multimode waveguide was 1.5 dB, compared with the propagation loss of a straight multimode waveguide.     

Measurement of eye-penalty based on the clock amplitude of transmitted signal

We investigate the relationship between the eye-penalty and the clock amplitude of the transmission signal. The simulation results for return-to-zero (RZ) signals show a good correspondence between the clock amplitude and the eye-penalty. For a non-return-to-zero (NRZ) signal, however, the correspondence between them is satisfied within the reasonable range of the transmission distance. Thus, we can monitor the eye-penalty by measuring the clock amplitude of the transmission signal. The proposed scheme may provide a cost-effective monitoring of the chromatic dispersion-induced signal distortion in optical transmission systems and networks.     

Painleve Integrability of Nonlinear SchrSdinger Equations with both Space- and Time-Dependent Coefficients

We investigate the Painleve integrabiiity of nonautonomous nonlinear Schr6dinger （NLS） equations with both space-and time-dependent dispersion, nonlinearity, and external potentials. The Painleve analysis is carried out without using the Kruskal＇s simplification, which results in more generalized form of inhomogeneous equations. The obtained equations are shown to be reducible to the standard NLS equation by using a point transformation. We also construct the corresponding Lax pair and carry out its Kundu-type reduction to the standard Lax pair. Special cases of equations from choosing limited form of coefficients coincide with the equations from the previous Painleve analyses and/or become unknown new equations.