Study of a narrowband reflection filter with multi-channels

Reflection filters have various applications in optical communication and other systems.In this letter,we propose a narrowband high-reflection filter composed of dielectric and metallic layers,in which an optimized filter combined with an admittance-matching layer with broad stop band is achieved.The structure can be expressed as Sub ｜ （HL）13H2L（HL）313Cr0.84H ｜ air,with full-width at half-maximum （FWHM） bandwidth of 2.5 nm.Based on this structure,reflection filters with multi-peaks are presented,and the law of distribution of peak positions is drawn.     

Surface relief resonant Brewster filters with multiple channels

In this paper, a new type of resonant Brewster filters （RBF） with surface relief structure for the multiple channels is first presented by using the rigorous coupled-wave analysis and the S-matrix method. By tuning the depth of homogeneous layer which is under the surface relief structure, the multiple channels phenomenon is obtained. Long range, extremely low sidebands and multiple channels are found when the RBF with surface relief structure is illuminated with Transverse Magnetic incident polarization light near the Brewster angle calculated with the effective media theory of sub wavelength grating. Moreover, the wavelengths of RBF with surface relief structure can be easily shifted by changing the depth of homogeneous layer while its optical properties such as low sideband reflection and narrow band are not spoiled when the depth is changed. Furthermore, the variation of the grating thickness does not effectively change the resonant wavelength of RBF, but have a remarkable effect on its line width, which is very useful for designing such filters with different line widths at desired wavelength.     

平衡滤波器的计算方法

文章介绍了将多级平衡滤波器转换成多级等效梯形网络的物理思想和具体方法，再利用计算梯形网络的程序算出多级平衡滤波器的输入阻抗和插入损耗。     

旋转不变振幅位相合成圆谐滤波器

提出了振幅位相合成圆谐滤器用于旋转不变模式识别，该滤波器的振幅是圆谐滤波器的振幅谱加偏移量后的逆函数，位相是圆谐滤波器的位相谱。计算机模拟实验证明，与传统的圆谐滤波器和纯位相圆谐滤波器相比，振幅位相合成圆谐滤波器具有更好的识别能力，能产生更尖锐的相关峰和更大的输出信噪比。     

埋入式光纤光栅应变测量系统的设计

埋入式光纤光栅应变传感器作为大型土木结构健康监测的智能元件具有很好的发展前景。讨论了埋入式光纤光栅应变传感器的传感机理，设计了埋入式光纤光栅应变测量系统。从力学角度阐述了光栅传感探头的结构和制作工艺。采用可调谐F-P滤波器对光栅信号进行解调，解决了应变与温度交叉敏感问题。系统对应变的测量范围为0～1500με。通过理论分析证实了系统方案的可行性。     

Structural and Optical Properties of Zinc Nitride Films Prepared by Pulsed Filtered Cathodic Vacuum Arc Deposition

Polycrystalline zinc nitride films are deposited on Coming 7059 glass substrates by pulsed filtered cathodic vacuum arc deposition （PFCVAD）. The crystallographic structure is studied by means of x-ray diffraction. These measurements show that all the films are crystallized in the cubic structure, in a preferred orientation along the （332） and （631） directions. Weak XRD signal shows small crystallites distributed in an amorphous tissue. A small improvement of crystallinity is observed with annealing. Optical parameters such as absorption, energy band gap, Urbach tail, extinction coefficients have been determined. The Urbach tail energy is decreased with annealing at 500℃ for one hour. Energy band gap values are found to be increased by annealing.     

一种新型密集波分复用滤波器的调谐特性分析

研究了一种新型模拟双折射结构DWDM滤波器的中心频率和带宽的可调谐特性.研究表明：当给定满足一定平坦化要求的光谱透射率所需的各模拟波片中偏振旋转器的旋转角时,通过模拟波片中楔形介质对的相对位移来调节光在各模拟波片中的光程差,同时保持光程差仍满足特定的比例关系,可实现中心频率及带宽的调谐.当光在各模拟波片中的光程差变化较小时,可实现中心频率的调谐,此时带宽的改变很小,可忽略不计；随着光程差变化的不断增大,带宽的改变则不能忽略.     

道路约束条件下的移动机器人跟踪

为提高移动机器人的位置估计精度和跟踪效果,提出一种基于道路约束条件下的移动机器人鲁棒约束H∞滤波(CHF)跟踪算法.首先,将机器人移动的道路网络作为跟踪的约束条件,并利用当前统计模型对机器人的运动进行建模.其次,将道路约束条件作为机器人跟踪的非线性状态约束,利用最小协方差估计推导了鲁棒CHF递推方程.通过拉格朗日乘子法对非线性约束优化估计问题进行求解,并利用约束信息对CHF算法的状态更新过程进行了改进.最后,通过对CHF算法和无约束的H∞滤波算法的跟踪性能进行了对比分析和验证.仿真结果表明,该算法可以实现机器人的跟踪,且跟踪精度优于HF算法.     

超导滤波器专用设计软件

开发了一套适用于高温超导滤波器设计的专用软件。利用该软件可快速得出高达20阶的任意结构的任意类型滤波器的传输方程、原型电路,并提取出其耦合系数矩阵。该软件可分析寄生耦合、基片厚度,介电常数误差等对滤波器的性能影响,并能由蒙特卡罗(Monte Carlo)法预测超导滤波器的产品合格率。此外,该软件提供了一个基于神经网络模型的计算机辅助调谐工具包。因而可解决超导滤波器设计、调谐的几乎所有问题,大大降低了其研制的难度和产业化的门槛。     

用多色菲涅耳全息滤波器作彩色图像特征识别

本文在用多色匹配滤波器(MSF)作彩色图像相关检测和用菲涅耳全息滤波器(FHF)作无透镜强度相关的基础上,提出一种把两者结合起来的技术,即用多色菲涅耳全息滤波器实现彩色图像的相关检测.