LiNbO3电光调制器行波电极微波等效折射率的测量

LiNbO3电光调制器的设计中,行波电极的微波等效折射率是一个重要的参数。该文通过自行设计的微波探针架及探针,采用差值的方法,在微波网络分析仪上对样品CPW电极的微波等效折射率进行了测量,分析了实测值与理论计算值的偏差,给出了修正因子,研究了微波等效折射率随频率变化的色散现象,并对这种测量方法进行了误差分析,提出了减小误差的方法。     

慢波结构色散测量中的探针引入误差分析

提出了一种微波器件色散测量中探针引入误差分析方法。该方法将探针对器件微扰的各种参数分离,便于对复杂结构进行分析,可以直接带人相关参数计算。提出分解微扰引人的误差省略其中的极小值,简化了计算。在此基础上,分析了不同探针对电磁带隙波导色散测量的误差,给出了探针器件位于不同位置以及不同探针半径所引入的误差相对值。计算结果表明,探针半径变化对测量误差的影响远大于探针位置变化对测量误差的影响。     

共面波导电极聚合物电光调制器多层结构研究

提出了两种基于共面波导(CPW)电极的多层聚合物电光调制器模型结构,分别为补偿层型结构和屏蔽层型结构。采用了保角变换的计算方法给出了基于CPW电极结构的多层电光调制器的特性参数的计算结果。与传统调制器结构性比较,补偿层型结构能够有效的减小光波与微波传输有效折射率的差,屏蔽层型结构不仅能够减小光波与微波传输有效折射率的差,而且能够通过优化结构参数,有效地消除了微波与光波之间的折射率差,可实现调制信号速率和调制电极阻抗的同时匹配。     

工艺误差对AWG串扰特性的影响

分析了阵列波导光栅器件的制作过程中引入的各种工艺误差。对波导尺寸误差、折射率误差以及长度误差进行了等效,并计算了位相误差和振幅误差的方差。最后分析了位相误差和振幅误差对阵列波导光栅的频谱特性尤其是相邻通道间的串扰特性的影响。     

康普顿型自由电子激光光导效应理论研究

对康普顿型自由电子激光（ＦＥＬ）光导效应进行了理论分析和数值计算。推导出适用于三维自由电子激光器中的电子束的等效折射率，说明高斯平面波激光场是电子束等效折射率按平方律分布即类透镜介质的结果。对自由电子激光强度和相位分布、光束半径以及等效折射率等进行了数值模拟，并对模拟结果进行了分析。     

用于折射率仪的高Q腔谐振频率跟踪系统

提出了一种用于折射率仪的采用方波调制的微波高Q腔谐振频率跟踪系统，分析了其工作原理。计算机仿真结果表明，系统跟踪速度快，稳定性好，无稳态误差；在小型微波折射率仪中的应用结果表明，作为系统输出的VCO频率对高Q腔谐振频率的跟踪灵敏度优于5×10-8f0（f0为高Q腔谐振频率）。     

微波折射率仪在探测海面蒸发波导的应用

微波折射率仪是一种利用微波技术对大气折射率进行直接测量的仪器,与气象参数测量大气折射率相比,具有测量精度高、测量速度快、适应性好的特点。介绍了一种新体制微波折射率仪的原理及构成,并对试验测试数据做出分析和结论,结合实地观测数据对微波折射率仪在海面蒸发波导的应用进行了分析。     

Ag膜电场辅助离子交换方法制作光波导

提出了银膜电场辅助离子交换方法制作光波导的理论,介绍银膜做电极与熔盐做电极制作光波导。对波导折射率进行分析,阐述了影响折射率的各种因素,最后给出了实验结果。     

脊波导结构LiNbO3电光调制器研究与改进

采用有限元软件Ansys、运用有限元法,对脊波导结构铌酸锂电光调制器进行了优化设计。通过将传统结构与脊波导的比较分析,提出采用聚四氟乙烯部分取代缓冲层中的二氧化硅的结构,能更好的实现微波等效折射率的降低以达到与光波折射率的匹配,同时能保持更大的特性阻抗以实现阻抗匹配,从而更好的提高器件性能。     

同轴电探针耦合测高功率微波

本文从理论上对同轴电探针耦合检测高功率微波进行了简明的分析，推导了在国波导中传输TM（mn）和T（mn）模耦合度的计算公式。设计了一种同轴电探针，并用此探针近似测量虚阴极振荡高功率微波发生器产生的单次脉宽30ns的高功率微波，测得X波段脉冲峰值功率为1GW左右。此种测量高功率微波的方法虽不很精确，但作为一种监测的手段，具有结构简单，使用方便等特点。     

Analysis and Demonstration of Mach–Zehnder Polymer Modulators Using In-Plane Coplanar Waveguide Structure

Analysis, design, and experimental demonstration of polymer Mach-Zehnder (MZ) modulators with a newly proposed in-plane coplanar waveguide (CPW) electrode are presented in this paper. Compared to the conventional CPW electrode, the new in-plane CPW configuration significantly enhances the overlap factor between microwave and optical wave by 40% from the theoretical calculations. Different from polymer modulators using the traditional microstrip electrodes, this structure can suppress dc bias voltage drift and widen modulation bandwidth. Using CLD1/APC and AJL8/APC electrooptic polymers, MZ modulators using the in-plane CPW are fabricated and tested. The measured Vpi's of the MZ with 15-mum gap spacing and 2 cm electrode length are 5.4 and 9.5 V at 1.55 mum for the AJL8/APC and CLD1/APC devices, respectively. The evaluated Upsi₃₃'s are 46 pm/V for the AJL8/APC and 26 pm/V for the CLD1/APC MZ. The dc bias stability is tested and compared for both the microstrip and the in-plane CPW electrode modulators. Experimental results show that the in-plane CPW modulator greatly improves the bias stability. From the microwave measurement, the microwave signal loss of the modulator using the in-plane CPW is much reduced to 0.2 dB/cmradicGHz, while 0.7 dB/cmradicGHz using the microstrip.     

Hybrid Electrodes Used in Polymer Electro-Optic Modulator with Ultra-Broadband

Hybrid electrode combined coplanar waveguide (CPW) and microstrip lines in ultra-broadband electro-optic modulators. The characteristics of the modulators with hybrid electrode is like that of the modulator with the microstrip lines, in which the microstrip electrode is loaded above only one arm of Mach-Zehnder (M-Z) optical waveguide, besides the problem of microstrip line to coaxial transition and corona polarization in polymer modulators have been best solved at the same time. By using finite element method (FEM), the characteristic parameters such as half-wave voltage, modulation bandwidth characteristic impedance, effective microwave refractive index of polymer modulators with microstrip line and hybrid electrode are analysed and compared in this paper. The results present that velocity match, impendence match and lower microwave propagating loss is easily realized in modulators with hybrid electrode.     

High-Speed X-Cut Thin-Sheet LiNbO3 Optical Modulator With Folded Structure

We propose a small-footprint X-cut thin-sheet lithium niobate optical modulator with high-speed and low-driving-voltage characteristics. Since an optical waveguide is folded by a mirror placed at one edge of the modulation chip, the chip can be shortened by about half. In addition, a wide modulation bandwidth can be achieved, because the path-length difference between the optical waveguide and the coplanar-waveguide (CPW) electrode is decreased to as short as possible by placing the CPW electrode as far as possible along the optical waveguide in the folded portion, and the microwave effective index is set to realize effective velocity matching between the lightwave and the microwave. A small footprint of 1.78 times 29 mm, a low half-wave voltage of 2.0 V at dc, and a 3-dBe modulation bandwidth of 20 GHz were obtained.     

几种复合传输线特性阻抗的计算

本文就高速光电器件微波封装提出了有希望的几种复合传输线（微带＋共面线，屏蔽微带＋共面线，微带＋不对称共面线），采用边界元法计算了它们的特性阻抗，给出了几组有工程价值的计算曲线，并讨论了实验结果。     

Microwave properties of traveling-wave electrodes in LiNbO3 electrooptic modulators

The microwave characteristics of a traveling-wave electrode in electrooptic modulators on z-cut LiNbO₃ crystals with buffer layers with various dielectric constants are calculated by a quasi-TEM analysis. The theoretical results are compared with the measured results on z-cut crystals for coplanar waveguide (CPW) electrodes. The agreement between the calculated and the measured results is good     

A CPW T-resonator technique for electrical characterization ofmicrowave substrates

An impedance independent method is proposed using a finite ground coplanar waveguide (CPW) T-resonator to electrically characterize microwave materials. Silicon-based CPW T-resonators are designed and measured, with calibrated data agreeing well with other methods up to 30 GHz. Uncalibrated measurements produce dielectric constant and attenuation results within 3.7% and 25%, respectively, of those obtained with calibration. Hence, the CPW T-resonator can be used to provide rapid and accurate characterization of microwave substrates with unknown dielectric properties     

Mach-Zehnder Type Annealed Proton Exchange Waveguide and Coplanar Waveguide Modulation Electrode LiNbO3 Intensity Modulator

The characteristics of a conventional LiNbO3 intensity modulator made up of a Mach-Zehnder （MZ） type annealed proton exchange（APE） waveguide and coplanar waveguide（CPW） modulation electrode are presented. The APE waveguide characteristics and their relations with process parameters are analyzed. At the same time, the electrical characteristics of modulation electrode, such as modulation voltage, microwave effective index associated with modulation bandwidth, characteristics impedance, are also investigated in detail.     

电吸收调制激光器集成芯片的高频测试

提出了一种精确测试电吸收调制激光器(EML)集成芯片高频特性的方法。待测芯片制作在带有微带线的热沉上,同时采用光探测器作为光电转换器,二者构成待测双口网络。被测双口网络的一端是共面线,使用微波探针作为测试夹具加载信号,另一端是同轴线,两个测试端口不同,不能采用简单的同轴校准方法校准待测系统。测试过程中采用扩展的开路-短路-负载(OSL)误差校准技术对集成器件的测试夹具微波探针进行校准,扣除了测试中使用的微波探针对集成光源高频特性的影响,同时采用光外差的方法扣除了高速光探测器的频率响应对结果的影响,得到集成光源散射参数的精确测试结果。     

High-speed shielded velocity-matched Ti:LiNbO3 opticalmodulator

A shielded velocity-matched Ti:LiNbO₃ optical modulator is investigated, focusing on the characteristics of the traveling-wave (TW) electrode and the optical waveguide. The optical waveguide is analyzed and its parameters are determined using the newly developed modified-step-segment method (MSSM). The TW electrode is analyzed using the second-order triangular element quasi-TEM finite element method (FEM). By taking the thickness of the coplanar waveguide (CPW) traveling-wave (TW) electrode into consideration, it is confirmed that there is an optimum overlaid layer thickness for a given electrode thickness. It is also shown that very wide modulation bandwidth can be attained by using the optimum CPW TW electrode thickness and overlaid layer thickness