Applied Mechanics and Materials Vols. 321-324

Abstract: An in-line all-fiber measurement system for polarization parameters is designed and fabricated in this paper. This system implements accurate control of polarization state, together with in-line, accurate, and high-speed measurement of Stokes vector. It can measure the light polarization parameters such as States of Polarization (SOP), Degree of Polarization (DOP), Light Polarization Extinction Ratio (LPER), and related losses of polarization. Besides, polarization monitoring and stabilizing can be achieved using this system. Because there is no discrete device concluded, the optical path of this system is completely constituted by optical fiber, which makes the entire system low-cost, with small size and low insertion loss. Keywords: All-fiber, polarization control, polarization measurement, in-line system, Stokes vector

Abstract: Thermal poling could make centrosymmetric fused silica optical fibers generate second-order nonlinearity effect and linear electooptic effect. In order to investigate the influence of thermal poling parameters on linear electooptic effect, a real-time test system, which mainly consists of an all polarization maintaining fiber Mach-Zehnder interferometer, has been utilized to monitor the whole thermal poling process in fibers. The processing parameters in thermal poling, such as applied poling voltage, poling duration and temperature, have been measured in real time. Based on those measurements, their influence on the linear electrooptic effect has been discussed. Experiment results show that the linear electrooptic coefficient would increase when a stronger electric field is applied on fibers. Considering the anti-high-voltage breakdown capability of fibers, a DC voltage from 3KV to 4KV is suitable for polarization in thermal poling. When using 3KV, the optimum poling duration is about 16 minutes and the best temperature for thermal poling is around 190°C. Keywords: electro-optic effect, poled fiber, thermal poling, real time test system, fiber optic interferometer

Abstract: Based on the analysis of the transmission process of light-beam in edge-lighting flat light-guide plate with Cold Cathode Fluorescent Lamp (CCFL) as a light source, this thesis achieved an arrangement formula and related method to design this kind of light-guide plate with scattering netted dots. According to the method, the designs of flat light-guide plate with scattering netted dots were simulated and analyzed by using ASAP software. Comparing the method with others, it was confirmed that the method was feasible and the good uniform luminance distribution on the flat light-guide plate for LCD was obtained by using this method. Key words: light-guide plate, scattering netted dots, the function of netted dots filling ratios

Abstract: The solid volumetric true−3D display requires light source with high brightness, high energy utilization rate and high frequency color field. So high−power red, green and blue LEDs with collimators were used as the projection light source. Firstly, the required quantity of LEDs was determined according to the required output luminance, the efficiency of the projector and the red, green and blue LEDs' parameters. Secondly, with the consideration of the LEDs' dimensions, light−emitting mode and output luminous flux, collimator was designed and simulation model was established. Simulation and practical measurement results both show that light source based on high−power LED meet the requirements of the solid volumetric true−3D display.

Abstract: The p-CuSCN /n-Si heterojunction diode have been prepared at a low cost by chemical method. The prepared hexagonal β-CuSCN films are polycrystalline nature. The heterojunction shows a good rectifying behavior and photovoltaic effects. The current and 1/C2 versus voltage curve of the p-CuSCN/ n-Si heterojunction diode was shown. The linear relationships of 1/C2 versus voltage curve imply that the built-in potential Vbi and the conduction band offset of the heterojunction ware found to be 2.1 eV and 1.5 eV, respectively. The current transport mechanism is dominated by the space-charge limited current (SCLC) conduction at forward bias voltages. The electronic potential barrier in p-CuSCN/n-Si heterojunction interface higher than hole at forward bias voltages. In this voltages area, a single carrier injuction was induced and the main current of p-CuSCN/n-Si heterojunction is hole current.This heterojunction diode can be good used for light emission devices and photovoltaic devices.

Abstract: Patterned sapphire substrate (PSS) is effective approach to improve external quantum efficiency of light emitting diode (LED) chip. The round holes pattern was studied in this paper. Simulation was used to study how external quantum efficiency changes in different parameters of the round holes for flip GaN-based LEDs fabricated round holes PSS. Through a series of comparisons on simulation results, the maximum enhancement of LED’s external quantum efficiency is 15% compared to the external quantum efficiency of non-patterned sapphire substrate (non-PSS) LED for a most effective pattern.

Abstract: This paper points out the properties of bismuth-based glass and the related design of photonic crystal fibers with flatted and normal group velocity dispersion profile. Supercontinuum generation in fiber is studied by a split-step Fourier numerical stimulation method. The results are shown for highly coherent mid-IR supercontinuum generation with 1.6 octaves bandwidth when pumping pulse width of 150fs and peak power of 40kW at 2.0μm. Analysis illustrates that supercontinuum generation dynamics are dominated by self-phase modulation and optical wave breaking.

Abstract: The Nd:YAG ceramic laser at 670 nm was studied by means of dispersion prism and KTP intracavity-frequency-doubling. We designed and optimized the cavity parameters by MatrixLaser software based on the standard ABCD ray propagation matrix. By using the laser diode arrays side-pumped Nd:YAG ceramic crystal with Nd doping concentration of 1.1at% and dimension of Φ3×50 mm, the Nd:YAG ceramic laser at 670 nm was realized. Under repetition rate of 1 000Hz and single pulse pumped energy of 144 mJ, the output energy of 5.1mJ at 670 nm is obtained. The optic-optic efficiency is 3.54%. The results not only formed the basis for the further development of the high power and high efficiency ceramic red laser, but also provided a great prospect for the high power ceramic red laser in the field of medical treatment, color display and other areas of application.

Abstract: Based on the further study on the dynamic dimming algorithms, the Inverse of Mapping Function (IMF) method, the error correction method and the cumulative distribution function (CDF) method are analyzed and applied to get the dimming level in the bottom-lit backlight. 50 typical images are simulated. The power reduction, contrast ratio enhancement, and MSSIM are explored to evaluate the 3 above dimming algorithms, the simulation results show that: IMF method does not apply to the low average luminance images; error correction method is suitable for a wide range of images, but the energy-saving rate is not high; though the energy-saving rate of the CDF method is higher than the other two kinds of algorithms, the image quality has a some kind of distortion.

Abstract: The aim of this study is to determine the optical parameters of the ternary alloys LaNi_4.5M_0.5 (M=Al, Mn) by using first-principles calculations. Through the computer simulation, we have successfully obtained the absorption coefficient, optical conductivity and dielectric function of these alloys. These alloys are transparent for the electromagnetic waves with frequencies of 12eV~15eV. The calculated dielectric constants are 188.3 and 257.6 for LaNi_4.5Al_0.5 and LaNi_4.5Mn_0.5, respectively. Our result is compared with the previous study and a good agreement is found.