全内反射型半导体光波导开关的位相变化

理论分析了全内反射型半导体光波导开关内的位相关系.数值计算了1.3μm InGaAsP/InP全内反射型光波导开关内的反射TE模和TM模的位相变化δ_s、δ_p和它们间相对位相差△δ.结果表明,光波导开关内开关区介质折射率变化量△n、吸收系数α和传输角θ_p对δ_s、δ_p和△δ值均有很大影响,它们间都有一种非线性变化关系.结果还表明,由于反射TE模和反射TM模间存在有相对位相差,全内反射型光波导开关将是一种有偏振特征的元器件.     

非对称全内反射型SOI波导开关器件模型分析

根据有效折射率法和光束传播法分析了大截面单模ＳＯＩ脊形Ｘ型交叉波导的传输特性．指出交叉角在１．５～２°内，因导波模式引起耦合作用而导致的串音小于－２５ｄＢ；采用波动光学原理分析了非对称全内反射开关导模的传输和反射特性；讨论了等离子体色散效应，Ｐｎ结大注入效应以及Ｇｏｏｓ－Ｈａｎｃｈｅｎ位移，并分析了非对称全内反射型ＳＯＩ光波导开关的电学性质．据此优化设计了该器件的结构参数和电学参数．     

视频反射损耗测试方法介绍

本文介绍了视频反射损耗对电视图像的影响及改善反射损耗的一般措施，详述了视频反射损耗的具体测试方法，并对不同的方法进行了分析比较。     

外界条件对FBG反射偏振相关损耗特性的影响

利用光纤光栅反射偏振相关损耗对外力场信息的变化进行监测,提高了测量性能,并研究了光纤布拉格光栅(FBG)反射偏振相关损耗(RPDL)随外界条件的变化。运用耦合模理论得出外界条件变化量与反射偏振相关损耗间的关系式,并模拟了温度、应力、压力的改变对反射偏振相关损耗谱线的影响。仿真结果表明:光纤光栅反射光的偏振相关损耗对外界温度、应力的变化不敏感,但却明显地依赖外界压力的变化。     

反射损耗的测量与改善措施

反射损耗是衡量电视设备终端阻抗匹配程度的一项重要指标。设备两端匹配良好,可以把反射的能量全部吸收,或者说对反射的能量损耗很大。所以,反射损耗愈大愈好。当图象信号源、卫星电视接收设备、传输电缆、有线电视网络、彩色监视器等接口有阻抗失配现象时,都会产生反射。轻者波形失真,重者会引起非常显著的轮廓效应或单个及多个重影。因此,反射损耗的测量显得尤为重要。     

全内反射型半导体光波导开关器件模型分析

本文提出了一种简便可行的全内反射交叉型半导体光波导开关模型分析方法。该方法采用波动光学的原理,分析了全内反射型(TIR)开关中导波模式的传输和反射特性,采用反射率和透射率计算了开关的消光比、串话、损耗等性能与波导结构参数之间的关系,并考虑了波导吸收系数对开关性能的影响。对全内反射条件下Coos-Haenchen位移也做了讨论。     

蝶形电极结构载流子注入全内反射交叉脊形光波导开关

分析了一种蝶彩电极结构交叉脊形光波导开关．这种结构可使波导交叉角增大，反射损耗降低，传输端的消光比提高，波导的数值孔径变大，且有较小的串音．     

电缆失配点的反射

电缆失配点的反射４３００７０武汉汽车工业大学电教中心杨春１引言反映传输电视信号的电缆阻抗失配状态引入了反射损耗、反射时延、反射量等概念，弄清楚这些概念的意义及它们之间的关系，对于处理系统电缆的故障大有益处。２反射损耗Ｒｌ信号通过一器件时，如果阻抗不匹...     

高性能193nm反射膜的制备与误差分析

分析了膜厚控制误差对反射膜设计曲线的影响,发现高低折射率材料厚度反方向变化时(高折射率膜层厚度增加,低折射率膜层厚度减小),反射膜的反射率变化不明显,设计的膜系结构对这种膜厚变化方式的制造误差宽容.在此基础上制备了193nm反射膜,结果表明退火前光学损耗相对较大,实验结果与理论计算结果存在一定差距,并且散射损耗在总的光学损耗中所占比例很小,而吸收损耗占光学损耗的主要部分,起主导作用.退火后光学损耗明显下降,实验结果与理论计算结果更为接近,193nm反射膜的反射率达98%以上.散射损耗增加至接近吸收损耗的水平,不过在总的光学损耗中仍然占比较小的比例.说明当吸收损耗下降到一定程度时,散射损耗所起的作用也是不可忽视的.     

固体反射光谱的挖孔机制——红外吸波材料机理探讨之三

深入研究了固体反射光谱红外活性模剩余反射带短波边对介电常数变化的敏感性，并在此基础上研究了强弱振子介电耦合对反射光谱的影响，发现在一定条件下可以在强振子的剩余反射带内形成局部的低反射率频域     

光子晶体Bragg镜的相移特性及腔模研究

研究了光子晶体Bragg镜的反射相移及透射相移,发现随着入射光频率的增大,相位均在增大。在中心频率附近反射相移和透射相移都与频率成线性关系。利用泰勒展开式的一级近似,得到了中心频率附近反射相移和透射相移的一级近似解析解,它们能很好地描述相移的变化规律。利用相移特性研究了Bragg微腔的共振模随微腔厚度的频率变化特性,同时亦给出了中心频率附近共振模频率的一级近似解析解。     

移相谐振PWM控制器UC3875在开关电源中的应用

开关损耗是开关电源高频化的主要障碍之一,开关管共同导通而留的死区时间,限制了开关电源工作频率的提高,而移相谐振PWM技术正是利用死区时间,通过谐振腔使开关管输出电容上的电压迅速放电,从而实现零电压或零电流开关,减少开关损耗和降低噪声干扰。文章介绍了移相谐振PWM控制器UC3875的工作原理及应用。     

Design and demonstration of polarization-insensitive Mach-Zehnderswitch using a lattice-matched InGaAlAs/InAlAs MQW and deep-etchedhigh-mesa waveguide structure

The authors have designed and demonstrated a 2×2 Mach-Zehnder switch in view of polarization independence as well as low propagation loss (α) and absorption change (Δα). To obtain polarization-insensitive refractive index change (Δn), a lattice-matched InGaAlAs-InAlAs multiple quantum-well (MQW) with a large detuning wavelength was used. Moreover, to reduce the insertion loss difference between polarizations, we applied a multimode-interferometer 3-dB coupler and a deep-etched high-mesa waveguide structure. This switch, therefore, can provide polarization-independent operation about both driving voltage and insertion loss, which is indispensable to practical optical switching applications. We also paid attention to Δα suppression when we decided the value of wavelength detuning and the length of the phase shift region. We also investigated the wavelength dependence of the switch. Within 1530-1560 nm, which is the erbium-doped fiber amplifier (EDFA) gain band, polarization independence in the driving voltage and the crosstalk was maintained. This result shows that the switch is also applicable in wavelength division multiplexing (WDM) applications     

基于双面反射镜的N×N光开关的特性分析和实验研究

报道了基于双面反射镜的N×N光开关器件。介绍了使用双面反射镜的2×2,4×4光开关的集成光路设计和工作原理;采用Benes网络,以2×2和4×4光开关为基本单元的N×N光开关器件的整体结构,并根据“一笔画”原理,分析了4×4,8×8和16×16光开关矩阵的可重排无阻塞特性和光开关矩阵的光路选择算法。最后,基于2×2,4×4光开关技术制备了16×16光开关矩阵。测试表明,该器件具有良好的插入损耗、回波损耗、串扰和开关时间等性能,从而验证了设计思想和工艺的可行性。在基于双面反射镜的光开关矩阵中,双面反射镜的使用大大减少了光开关矩阵中运动镜片的数量,简化了控制程序,并有利于提升光开关器件的可靠性能,有望在中小型光交换机、网络管理和光路测量中获得应用。     

Improved 8×8 integrated optical matrix switch usingsilica-based planar lightwave circuits

An improved 8×8 optical matrix switch was fabricated using silica-based planar lightwave circuits (PLCs) on a silicon substrate. Three improvements were made. First, the waveguide material was changed from titanium-doped silica (SiO₂₂-TiO₂) to germanium-doped silica (SiO₂₂-GeO₂) to reduce propagation loss. Second, offset driving powers were supplied to every switch unit to realize high extinction ratios. Third, the dummy switch units were modified to suppress the crosstalk through these units. The average insertion loss of the fabricated device was 3.81 db in the TE mode and 3.82 dB in the TM mode. The average extinction ratio of the switch units was 25.3 dB in the TE mode and 22.3 dB in the TM mode. The accumulated crosstalk was estimated to be less than -14 dB in the TE mode and -11 dB in the TM mode. The average driving power of the phase shifter in the on-state was 0.54 W in the TE mode and 0.52 W in the TM mode. The switching response time was 1.3 ms. The packaged 8×8 matrix switch with additional fiber-waveguide coupling loss of 2.7 dB was successfully employed in photonic multimedia switching and photonic inter-module connector system experiments     

A wide range,high yield and good performance pHEMT switch for MMIC phase shifter

A low-cost method with high yield and good performance is presented by pHEMTs (pseudomorphic high electron mobility transistors) to be used in phase shifter switches. In this method, the capacitor in “off” mode (C_off) of transistor is reduced, without variation of the transistor structure. The transistor structure in switch mode can be optimised. This method increases the transistor isolation in turn “off” mode, while there is no change in resistance of the transistor in “on” mode (R_on). Transistor dimension is determined in turn “off” mode (V_g = ?4.5 V) and standard form of 4 × 75 μm. So, in this method, insertion loss will be reduced without a perceptible change in transistor dimension. Thus, design and fabrication capability of some circuits such as phase shifters, antenna switches, SPDT (single port double throw) – without any change in technology – are increasing. In this paper, post layout and measurement result for a sample block of phase shifter are shown.     

热处理对低损耗高反膜特性的影响分析

低损耗激光薄膜反射镜是环形激光器谐振腔的关键元件之一,首先设计和制备了工作角度为45的低损耗高反膜。为了提高低损耗高反膜的光学性能,采用高温热处理的方式,研究了热处理对低损耗高反膜的透射率、散射系数、表面粗糙度、相移等特性的影响。高温热处理对高反膜的散射系数、表面粗糙度影响较小,随着热处理温度的增加,高反膜相移逐渐降低。当退火温度为550 ℃时,环形激光器输出性能稳定性最好,当工作230 h 后,输出能量仅下降到初始值的90.5%。实验结果表明,采用合适的热处理方式,可以有效改善低损耗高反膜特性以及环形激光器的输出性能。     

A Fast 3-mm Ferrite Switch (Correspondence)

A tetrahedral waveguide junction type of switch has been developed for use in the millimeter region. The design employs a permanent magnet such that the switch operates in the transmission state without any external dc power. By applying a current pulse it switches from the transmission state to the reflective state in 400 ns and back to the transmission state in less than 200 ns. Over the frequency range of 95.5 to 97.2 GHz the switch exhibits a maximum insertion loss of 1.0 dB and a minimum isolation of 25 dB.     

光子晶体的反射振幅系数比特性的理论研究

运用光学传输矩阵法,通过数值模拟计算,研究了一维光子晶体中两偏振光（p波和s波）反射振幅系数比的两个参数与其它因素的关系。研究结果表明,对于不同折射率,不同光学厚度组合的一维光子晶体,反射光的振幅系数比变化是不同的。其反射光的相位差随入射角的改变而发生变化。利用相位差可连续改变的特性可以制成效率极高的反射型相位补偿器。     

Phase variations due to dispersion in inhomogeneously broadened lasers

One-dimensional analytical solutions for irradiance and phase are obtained for a two-level ring resonator model of a long inhomogeneously broadened chemical laser with strong velocity changing collisions (momentum cross relaxation). The solutions give the longitudinal mode spectrum of the laser line in terms of the ratio of elastic to inelastic collision rate, the Doppler linewidth, the product of small-signal gain times the length of the gain medium, and the resonator loss. The intensity is given in terms of the width of the mode spectrum, the saturation intensity, and the gain-length product. The phase in a single pass is given in terms of the mode spectrum, the loss, and the ratio of homogeneous to inhomogeneous width. For typical conditions the phase difference relative to line center for a detuning frequency near the edge of a laser line is less than about one twentieth of a wavelength for a single pass through the resonator. Application to unstable resonator geometries suggests that the total phase difference at the edge of such a laser may reach a few tenths of a wave, although most of the power in the line has a much smaller phase variation.