Bistable switching in the lossy side-coupled plasmonic waveguide-cavity structures.

We show numerically that the lossy side-coupled plasmonic resonators can be used as bistable switches without compensation. While the internal loss imposes on the bistable characteristics by reducing the transmission contrast and raising the input power requirement, it makes the switching more available by enlarging the width of the hysteresis loop. We also correct the nonlinear transmission formula of the resonators to adapt the lossy condition. Both the theoretical and simulation results are in good agreement.

High transmission contrast for single resonator based all-optical diodes with pump-assisting.

We present a detailed analysis of realizing the unidirectional transmission by using the bistability of a nonlinear optical resonator. We show that the transmission contrast can be enhanced by an order of magnitude if the upper branch of hysteresis loop is explored with pump-assisting. It provides all-optical diodes with simple configuration and high transmission contrast.

[Influence of sun radiation on optical properties of liquid crystal display device].

Sunlight affects mainly the light stability and life of liquid crystal display device, which will lead to rapid aging of the device. By measuring the optical properties of liquid crystal display devices radiated with different time by spectrophotometer, the influences of long time sunlight radiation on the optical properties of the device were studied, and the changes of its optical properties were analyzed. The results indicate that structural and optical properties of liquid crystal slices of calculator LCD (B group) and telephone LCD (C group) are similar and the qualities are relatively good, while the aging problem of personal computer LCD (A group) liquid crystal slice is more serious than those of B and C groups, moreover, the qualities of liquid crystal slices in A group are worse. The structural and optical properties of liquid crystal display device will change accordingly after long time sunlight radiation. The surface of liquid crystal display device will become yellow and nigrescent, and the spectrum transmission properties will decline markedly, which is related to liquid crystal materials and manufacturing techniques.

[Analysis of spectral properties of car solar films].

A dual-beam ultraviolet/visible spectrometer (UV-Vis 8500) automatically controlled by computer was used to measure qualitatively and to analyze the spectral properties of car solar films of a certain brand in the market. The experimental results indicate that transparency characteristics of the ordinary series of solar films are well, but their violet insulation and heat insulation properties are moderate, and moreover, their thermal-proof property is not ideal. The heat insulation, violet-proof and transparency properties of the anti-crack series are all in normal level. The heat insulation and transparency properties of anti-crack and anti-wear series are moderate, however, their violet insulation characteristics are better than those of other series mentioned above. For the super front film, its transparency property is excellent, moreover, its violet insulation and heat insulation properties are quite well. In general, it can be concluded that the super front series are the best car solar films.

[Study on photoelectric dispersion characteristic of liquid crystal light valve].

The electro-optical properties and dispersion characteristics of a liquid crystal light valve (LCLV) were investigated. A 90 degrees twisted light valve (model TB3639) was used as a typical LCLV in the authors' experiment. At 27 degrees C and a fixed frequency of 1000 Hz, the transmitted light intensities (T) of the LCLV were measured as a function of wavelength (lamda) at different applied voltages. From the measured T-lamda curves, the dependence of contrast ratio k on the wavelength can be derived. The authors' results showd that the TB3639 LCLV has a comparatively high contrast ratio and low dispersion within the visible region. In the range of 450-750 nm, the contrast ratio, with its value higher than 0.8, does not change much with the wavelength. Particularly the contrast ratio is higher than 0.95 with a minimum dispersion in the range of 550-670 nm.

Enhancement of unidirectional transmission through the coupling of nonlinear photonic crystal defects.

We investigate the unidirectional transmission behavior of coupled photonic crystal defects with nonlinearity by using the coupled mode theory, focusing on how to enhance the transmission contrast. Although the unidirectional transmission originates from the asymmetric configuration and nonlinear property of the structure, it is revealed that the maximum transmission contrast depends mainly on two linear factors. For two coupled defects, they are the highest order of the frequency detuning appearing in the transmission formula and the frequency splitting due to the coupling. Our analyses are supported by the numerical simulations based on the finite-difference time-domain technique. An enhancement of the maximum transmission contrast by an order of magnitude is achieved in the structure consisting of two coupled defects.

Dynamic shift effect on bistability in nonlinear optical microcavities.

The shift of optical cavity modes oscillates due to the time-varying refractive index under Kerr nonlinearity. To reveal its impact on bistability, we present a time-average approach that includes this dynamic shift characteristic in the expression of nonlinear transmission. It predicts the monotonous decrease of the maximum transmission with the increase of the frequency detuning. Also, the frequency detuning to start bistability should be corrected as about 2. Our analyses are supported by the simulations based on the finite-difference time-domain technique.