强混响背景下悬浮目标的时反成像

提出了一种加权宽带全信号子空间时反成像方法,将扩展性目标建模为有限数量个、相互独立的点散射体构成,实现了时反成像在可疑目标区域的全信号子空间和整个宽带的累加。在实验室波导水池中,底部放置圆柱筒制造混响背景,共进行了两个实验,一是扩展性的悬浮目标位于圆柱筒附近,其回波与圆柱筒反射的混响不在同一个时间窗内,二是弱点目标回波与圆柱筒反射的混响重叠于同一个时间窗内,对所提出的方法进行强混响背景下弱悬浮目标的成像能力验证。结果表明,此方法对强混响背景下的弱悬浮目标的成像质量明显优于传统的时反成像方法。     

基于光谱解调的对称波导型表面等离子体共振传感研究

表面等离子体共振(SPR)传感系统有角度谱、光谱、强度、相位等解调方式,其中光谱型的(SPR)传感系统因可以使用光纤导光,将传感部分独立出来,可进行远距离传感和现场检测,并能有效缩小系统的体积。对称光波导型(SOW)SPR因金属膜层两边的折射率完全相同,表面等离子体波传播距离更长,穿透深度更深,比传统的SPR系统具有更高的灵敏度和分辨率。对对称波导型(SOW)SPR进行光谱解调研究,以MgF₂-Au-MgF₂结构的SOW-SPR为传感单元,同时以光纤输出的卤素灯为光源, 搭建了一套光谱解调的SOW-SPR检测系统,以不同浓度的葡萄糖溶液对系统折射率分辨率进行测量,得到2.8×10-7 RIU的分辨率。为SOW-SPR系统小型化、现场检测以及远距离探测提出一种可能实现的手段,具有很好的应用前景。     

三角形折射率剖面光纤一级修正解的数值计算

在弱波导近似下,用标量Helmholtz方程的解作为零级近似解,考虑了折射率梯度的影响,把∇ε项看作微扰项,用微扰法给出了具有色散位移特性的三角形折射率剖面单模光纤一级修正解的积分表达式,并给出了数值计算结果.原则上,该方法亦可用于多模光纤.     

LiNbO3质子交换波导及其退火效应

采用质子交换技术,以苯甲酸为交换源,实验研究X-切LiNbO₃质子交换平面波导及其退火效应。利用棱镜耦合器测出波导模折射率。采用费米函数,由模折射率确定出波导折射率分布随退火时间的变化关系,给出了分布参数和曲线.     

有损耗波导中非线性TE波的数值模拟

本文发展了一种以有限元技术为基础的数值方法,用它分析有损耗波导中的非线性TE模。在这种方法中,非线性有损耗波导中TE波与功率有关的复传播常数和局城电场分布,可从这种波导直接得到,没有任何近似。作为这种方法的应用,计算了非线性有损耗波导系统中TE0模的功率色散关系和电场分布。     

Investigation of Waveguide Y-Junction Circulator with a Triangular Ferrite Post

An H-plane waveguide Y-junction circulator with a triangular ferrite post is investigated by a modified analysis of jointly resonance theory and simple field theory. Good agreement between the theoretical obtained performances and experimental results is observed. The circulator exhibits a very low insertion loss and a wide bandwidth.     

Effect of Material Response Time on Optical Bistability in Nonlinear Distributed Feedback Gratings

The dynamic behaviors of nonlinear periodic waveguides with a finite material response time have been investigated by numerically solving both the coupled-mode equations and Debye relaxation equation. When the response time of the nonlinearity is more than the transit time through the grating, a modulational instability is sufficiently suppressed and one can obtain optical bistability. Unlike a nonlinear Fabry-Perot resonator or ring resonators, overshoot in the transmission never takes place in the case of zero detuning. However, a relaxation (or damped) oscillation always takes place in the presence of detuning. It is also found that the switch-on time depends on the material response time and the switch-off time is almost independent of it.     

An Optimum Sectional Waveguide Taper for Quasioptical Transmission Lines

The paper considers an optimum sectional waveguide taper (OSWT) which at a shortest length of the transition region provides nearly adiabatic propagation of the fundamental mode between circular, widely different in diameter quasioptical transmission lines of class hollow dielectric waveguide (HDW). Derived as a consequence of coaxial circular-horn sections, the OSWT offers all the advantages of a simple geometry and lends itself to simple fabrication techniques. The relationships among the critical geometrical parameters and the loss calculation formulae are presented. The comparison studies show that even at a few sections, the OSWT is almost as good in performance as the parabolic taper, but the OSWT is much better from a mechanical viewpoint. And compared to the ordinary linear taper, the OSWT allows essential cut in length and loss with the broadbandness kept. The HDW-based four-sectional OSWT has been fabricated and tested in a quite broad wave range 2,5-8 mm. The testing results lend a good support to the analytical formulae lying at the basis of the design software.     

矩形介质光波导的条形传递函数方法

将条形传递函数方法引入矩形介质光波导传播特性的分析计算,从标量波动方程的变分表达式出发,推导和建立了条形传递函数方法的基本方程和两种应用模型,作为算例,给出了阶跃型折射率分布矩形介质光波导的数值计算结果,并与其它方法进行了比较,表明了此方法的精度及对光波导问题的适用性。     

基于KH560修饰的有机/无机杂化材料电光波导制备

利用溶胶-凝胶法制备了硅烷偶联剂KH560修饰的有机/无机杂化电光材料,分析了KH560的水解缩合的反应机理.对制备好的电光薄膜进行了表面形貌、折射率和电光特性的表征,并用反射法测量得出了该材料的电光系数为3.5pm/V.针对这种材料柔韧的特性,设计了上加载条形电光波导,并利用Opti-BPM软件模拟了二维和三维光场.摸索了其制备的加工工艺,制备了该结构的光波导,最后得到了这种波导的近场输出.