Periodic,quasi‐periodic,and random quadratic nonlinear photonic crystals

Quadratic nonlinear photonic crystals are materials in which the second order susceptibility χ⁽²⁾ is spatially modulated while the linear susceptibility remains constant. These structures are significantly different than the more common photonic crystals, in which the linear susceptibility is modulated. Nonlinear processes in nonlinear photonic crystals are governed by the phase matching requirements, which are determined by the reciprocal lattice of these crystals. Therefore, the modulation of the nonlinear susceptibility enables to engineer the spatial and spectral response in various three‐wave mixing processes. It enables to support the efficient generation of new optical frequencies at multiple directions. We analyze three wave mixing processes in nonlinear photonic crystals in which the modulation is either periodic, quasi‐periodic, radially symmetric or even random. We discuss both one‐dimensional and two‐dimensional modulations. In addition to harmonic generations, we outline several new possibilities for all‐optical control of the spatial and polarization properties of optical beams in specially designed nonlinear photonic crystals.     

Self-calibration in a fiber optic sensing system using the walk-off compensation

We firstly present a concept of a self-calibration of the classical and quantum parameters’ measurement using a fiber optic system. The measurement of the change in phase of the optimum entangled states’ visibility is performed in terms of a walk-off length, i.e. birefringence. The applied physical parameters on the sensing fiber can be simultaneously measured and the self-calibration respecting the birefringence performed. The scheme of the entangled photons generation in fiber optic is reviewed and the walk-off on the polarization entangled states presented. The potential of self-calibration and simultaneous measurement using an interferometric sensing technique and fiber grating sensor are proposed and discussed. The walk-off on the entangled states in the thermal-controlled environment is presented and discussed.     

基于ATmegal6和μC／OSⅡ低成本的三轴联动平台的设计

提出了一种低成本的运动控制平台设计方案。将μC／OSⅡ嵌入式实时操作系统移植到平台采用的单片机中，并采用步进电机细分技术实现了三轴平台的联动。实验测定了三轴联动平台对命令的延迟响应时间，结果表明本方案可以应用于低成本的自动化设备中。     

Development of a PC interface board for true color control using an Ar–Kr white-light laser

For the optimal laser display, it is crucial to select and control color signals of proper wavelengths in order to construct a wide range of laser display colors. In traditional laser display schemes, color control has been achieved through the mechanical manipulation of red, green, and blue (RGB) laser beam intensities using color filters. To maximize the effect of a laser display and its color contents, it is desirable to generate laser beams with wide selection of wavelengths. We present an innovative laser display control technique, which generates six channel laser wavelengths from a white-light laser using a RF-controlled polychromatic acousto optical modulator (PCAOM). This technique enables us not only to control the intensity of individual channels, but also to achieve true color signals for the laser beam display including RGB, yellow, cyan, and violet (YCV), and other intermediate colors. For the optimal control of the PCAOM and galvano-mirror, we designed and fabricated a PC interface board. Using this PC control, we separated the white-light from an Ar–Kr mixed gas laser into various wavelengths and reconstructed them into different color schemes. Also we demonstrated the effective control and simultaneous display of reconstructed true color laser beams on a flat screen.     

STUDY ON A THREE DIMENSIONAL CHAOTIC SYSTEM

In this letter a new chaotic system is discussed. Some basic dynamic properties, such as symmetry, dissipation, continuous spectrum and chaotic behaviors of the butterfly attractor are studied. Furthermore, period-doubling bifurcations in a system with definite parameters has been investigated.     

瞬态光谱量子分析及其测量

介绍了新近研制的瞬态光谱测量仪，详细分析了瞬态光谱测量中的量子转换过程，进而表述出瞬态光谱信噪比表达式、图像参数和光电转换量子效率、光电成像有效积分时间和CCD光敏面的作用，最后给出了在此理论指导下的实测光谱曲线。     

Fiber optic flow and cure sensing for liquid composite molding

The Polymer Composites group at the National Institute of Standards and Technology has efforts in both on-line flow and cure sensing for liquid composite molding. For our flow program, a novel fiber optic real-time sensor system has been developed that can sense resin at various locations on a single fiber using long-period gratings and a polychromatic source. The sensor operation and characterization will be discussed along with sensor performance during mold filling with various types of reinforcement. The cure sensing program focuses on the interface-sensitive fluorescence response of a dye molecule grafted to a high-index glass fiber. The fluorescence emission of the fluorophore undergoes a blue shift as the resin cures. The fluorescence sensor is made by grafting a silane functional fluorophore onto the surface of the glass with close attention to layer thickness. Fluorescence emission of the grafted fluorophore film is shown to be sensitive to epoxy resin cure, co-silane, and layer thickness. The response of the grafted fluorophore to cure on a high-index fiber is demonstrated.     

Multisim仿真软件在三相电源相序检测中的应用

介绍一种EDA(电子设计自动化)仿真软件M u ltis im 2001应用在三相电源相序检测的仿真方法;建立三相交流电源,设计相序检测电路;调用仿真软件提供的测试工具和仪表进行仿真,根据仿真结果进行分析和观测三相电源相序的变化规律.     

A Differentiating Fiber-optic Ring Interferometer

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The Experimental Study on Wide band Tunable All-fiber Acousto-optic Filter Based on Null Coupler

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