二维光子晶体波导与单模平面介质波导间的喇叭波导接头

提出并优化了用于二维介质柱光子晶体波导与单模平面介质波导对接的基于分布布拉格反射波导的喇叭波导接头，提高了这两种波导之间的传输效率.二维时域有限差分仿真结果表明，在大部分光子晶体波导导模的频谱范围内，传输效率高于98％.传输效率最高可以达到99.85％. 关键词： 光子晶体波导 平面介质波导 时域有限差分     

液晶-金属光子晶体波导的光学特性

运用时域有限差分方法分析了二维液晶-金属光子晶体波导的光学特性。二维正方晶格金属光子晶体波导位于两个电极之间,其背景介质为液晶。通过在电极上施加不同电压,电场诱导液晶取向以改变液晶的折射指数从而改变光子晶体的带隙结构。数值计算结果表明:通过外界电场控制所填充的向列相液晶的方向可以对这种金属光子晶体波导的光学特性进行调节,该波导可用于制作光子晶体光开关等光学器件。     

二维三角晶格光子晶体波导的出射光集束传播

为了解决光子晶体波导出射端光场控制, 同时解决二维三角晶格光子晶体波导出射光辐射困难的问题。利用二维三角晶格光子晶体设计了一种新型光子晶体波导出射口结构。在二维三角晶格光子晶体波导出射端引入两个微腔, 通过光波与微腔发生共振, 形成类似于三个点光源干涉的出射光, 同时进一步提出波导出射端喇叭口干涉出射光定向辐射的设计。通过这种微腔喇叭口设计, 利用时域有限差分法分析结果表明光波实现很好的定向辐射, 并且辐射距离显著提高。     

光子晶体波导定向耦合器

在完整二维光子晶体中引入线缺陷后，就形成了光子晶体波导；将时域有限差分方法(FDTD)用于光子晶体波导耦合研究，计算了不同耦合长度情形下的波导各个出口处的透过率，结果表明：光子晶体波导耦合遵循普通介质波导耦合的一般规律，也有定向耦合的功能。进一步的研究表明：对于不同的频率，光子晶体定向耦合器耦合系数是不同的，并且耦合系数和对应的频率之间近似直线关系。     

光控液晶光子晶体微腔全光开关

设计了一种缺陷模迁移光子晶体微腔全光开关. 两条二维三角晶格空气孔光子晶体波导由一个光子晶体微腔连接, 在微腔的点缺陷中填充掺有少量偶氮聚合物的苯乙炔类液晶. 通过调节控制光的偏振态, 使偶氮聚合物发生顺-反异构化反应, 带动液晶分子重新取向, 从而改变光子晶体微腔的谐振波长, 进而实现光的通过与截止. 运用时域有限差分法和平面波展开法分析 了二维光控液晶光子晶体微腔全光开关的光学特性. 数值计算结果表明: 对于1.55 μ通信波段通过外界偏振光控制所填充的向列相液晶 的折射率可以实现对光波的导通与截止. 分析结果显示, 此开关具有阈值低, 消光比较大, 体积小等优点. 关键词： 二维光子晶体微腔 波导 时域有限差分(FDTD) 液晶     

二维空气孔型光子晶体负折射平板透镜的减反层

提出并优化了由单排渐变介质波导构成的二维空气孔型光子晶体负折射平板透镜表面的减反层，改善了成像质量.二维时域有限差分模拟计算结果表明，采用减反层后，在入射角小于23°的范围内，在使得有效折射率n_eff=-1的工作频率处，光子晶体表面对从空气一侧入射的平面波的反射率可降低到1％以下. 关键词： 光子晶体 负折射 平板透镜 减反层     

二维光子晶体分束器的分频效率分析

在完整的二维光子晶体中引入线缺陷,形成了光子晶体波导.设计了一种二维光子晶体三通道分束器,采用时域有限差分方法(FDTD),从理论上计算该器件3个通道电磁波的透射率.为了提高电磁波的透射率,通过在波导附近调节介质柱半径,引入两组点缺陷.结果表明,两组点缺陷的介质柱半径选择合适的值,在3个通道中可以得到最佳的电磁波透射率...     

用三维并行时域有限差分算法研究光子晶体薄板W3波导传输特性

构建了用于高性能并行计算的PC机群环境，将基于此机群环境的三维并行时域有限差分算法用于光子晶体薄板W3波导传输特性研究.性能分析表明：对于大规模问题，机群并行FDTD算法能够获得较理想的加速比.具体计算了W3波导的透射率频谱和光场分布.结果表明：光子晶体薄板W3波导能够实现光的三维约束，其导带中存在着微小禁带（mini-gap）.     

二维光子晶体六通道波分复用器的透射谱

设计了一种由微米尺度二维光子晶体构成的六通道波分复用系统。该系统包括利用光子晶体线缺陷实现的波导部分和利用光子晶体微腔实现的频率选择部分。采用时域有限差分方法（FDTD）,研究光在该系统中的传输特性。     

光子晶体共振现象研究

完整二维光子晶体中引入点缺陷后，在光子晶体禁带中会有共振模出现；将时域有限差分方法(FDTD)用于光子晶体共振特性研究中，给出共振频率的位置，直观地给出共振现象发生的过程。     

高功率过模圆波导到两路矩形波导功分器

基于模式匹配法分析了高功率过模圆波导到两路矩形波导功分器在传输过程中高阶模式的传输和反射问题,分析得到了高传输效率对过模圆波导的要求,并以此仿真设计了中心频率为2.88GHz的功分器,设计结果表明:在中心频率下反射系数为0.05,对应的圆波导TM01模到矩形波导TE10模传输效率大于99%,真空中功率容量为2.83GW;在2.82~2.94GHz的频带范围内反射系数小于0.1,对应的传输效率大于98%。     

Pure Reflection and Refraction of a Surface Polariton by a Matched Waveguide Structure

We study the fundamental problem of reflection and refraction of a surface polariton as it strikes the interface between two waveguide structures. By making the two waveguide structures match to each other, coupling of surface polaritons to radiating modes is cancelled, and the reflected and transmitted waves consist of only surface modes. The reflection and transmission coefficients are calculated, and negative refraction of surface polaritons is demonstrated. Finite-difference time-domain numerical simulations are also performed to verify the analytical results. As one of the applications of the matched waveguide structure, a square corner reflector for phase-retardation-free reflection of surface polaritons is proposed.     

Transmission characteristics of optical waveguide corners

Two-dimensional dielectric waveguide corners with air reflector or metal reflector have been investigated by means of the method of plane-wave expansion, which has the advantage of being compact for optical integrated circuit applications. The operating principle of these waveguide corners is based on the total internal reflection or large partial reflection. The corner losses and field profiles are presented for various waveguide parameters. It is found that the corner loss can be small if the waveguide corner is properly fabricated.     

Analysis of Oversized Sliding Waveguide by Mode Matching and Multi-Mode Network Theory

Transmission and reflection coefficients of hybrid modes in the sliding waveguide are discussed on the basis of mode matching method and multi-mode network theory. It is confirmed that the decrease in power of < 0.2% at 84 GHz is obtained for 2 cm in gap of the sliding waveguide which is composed of the corrugated waveguide with 88.9 mm diam. and the smooth-wall waveguide with 110 mm diam. At the sliding length near multi-half-wavelength in vacuum, transmission and reflection powers in the sliding waveguide change slightly, because the very small amount of standing wave in high higher-mode is produced resonantly in the gap.     

Waveguide grating mirror for large-area semiconductor lasers

We have fabricated and tested a waveguide grating mirror that uses anomalous reflection of light associated with excitation of waveguide modes. Sharp features are observed in the reflection spectra in both the wavelength and the angular domains. We confirm experimentally that, when the waveguide grating mirror is placed a short distance in front of a large-area semiconductor laser, it can control the emission spectrum. This demonstration opens a new approach to the design of very compact semiconductor lasers operating in the single-frequency-single-mode regime.     

Analysis of Dielectrc-Filled Waveguide Coupling to Plasmas in the ICRF

Dielectric-filled waveguides may be advantageous for heating reactor-grade tokamak plasmas, due to their compactness and power-handling capability. We present a theoretical analysis of coax excitation and plasma impedance for a dielectric-filled rectangular waveguide. The plasma reflection coefficient is obtained by matching plasma and waveguide fields at the interface. The numerical results show that the reflection coefficients can be made small by careful tailoring of the waveguide dimensions to the density profile for heating at the second or third harmonic of deuterium. We present a scattering matrix approach for the design of a coaxial feed to match the waveguide in the presence of a wide range of plasma loading. For a waveguide filled with a high permittivity dielectric, a shorted probe gives better coupling than an open-ended probe.     

天线罩电厚度与材料电参数六端口测量系统设计

 介绍了一个可用于天线罩电厚度与介质材料介电常数测量的六端口反射计系统，它由对称波导五端口结与定向耦合器组成，其关键部件波导五端口结用HFSS软件仿真与设计。介绍了天线罩相对电厚度复反射系数的测量方法。用该系统对滑动短路器复反射系数进行了测量，测量结果表明，系统工作稳定，测试精度高。利用短路波导法测量了材料介电常数和损耗角正切，测量结果显示：介电常数测量的精度和稳定度较高，损耗正切的测量误差较大。     

SHG in Bragg reflection waveguides for enhanced bandwidth applications

A novel scheme for second harmonic generation in asymmetric Bragg reflection waveguides is presented for enhancing the bandwidth of non-linear interaction. The strong dispersion exhibited by the Bragg reflection waveguide is exploited for countering the rapidly falling efficiency as one moves away from the phase-matching wavelength. The role of the periodic cladding on the efficiency and bandwidth of second harmonic generation in a lithium niobate based Bragg reflection waveguide is analyzed. Such an idea could be used in other parametric processes for enhancing the bandwidth and for easing fabrication tolerances.     

Photonic crystal waveguide sampled gratings

Photonic crystal waveguide sampled gratings (PCWSG) are proposed to realize multi-channel optical filter in a photonic crystal (PC) waveguide. The reflection characteristics of the filter are analyzed by using the coupled-mode theory (CMT) together with transfer-matrix method (TMM). It is shown that the reflection spectrum of the filter exhibits a group of reflection peaks, which are distributed with equal frequency spacing within the photonic crystal bandgap (PBG). The theoretically calculated results are numerically verified by using two-dimensional (2D) finite-difference time-domain (FDTD) method.