共面微带传输线超短电脉冲传输特性

本文用快速傅里叶变换对LTGaAs衬底共面微带传输线光生超短电脉冲的时域传输特性进行了数值计算结果表明,THz以上高频范围的模式色散、LTGaAs衬底切伦科夫辐射衰减使超短电脉冲信号沿LTGaAs衬底共面微带传输线超传输时波形畸变,初始光生电脉冲越窄,则信号波形畸变越严重减簿衬底厚度可降低LTGaAs衬底共面微带传输线的模式色散和辐射衰减,有利于改善LTGaAs衬底共面微带传输线亚皮秒超短电脉冲的传输特性.     

用于高功率激光装置中的电脉冲整形系统

采用射频GaAs场效应管和微带传输线技术,研制出用于高功率激光装置中的电脉冲整形系统.该系统电脉冲整形宽度为3.5 ns,幅度在0~5 V范围内调节,时域调整精度200 ps.整形后的方波,前沿383 ps,后沿642 ps,顶部不平坦度4~5%,波形幅度稳定性4~5%（p-p).利用该系统产生的整形电脉冲驱动电光波导调制器进行激光脉冲整形,得到了理想的整形激光脉冲.     

利用波导调制器实现连续可调任意整形激光脉冲

目前，惯性约束聚变激光驱动哭有级的发展方向是以稳定性好的激光二极管取代原来的闪光灯泵浦，以集成光学和光纤技术取代原来的块状光学调制器进行激光脉冲的整形工艺。本文从实验上研究了以激光二极管泵浦的固体激光器作为光源，以波导调制器作为整形器件的激光脉冲的整形和频谱展工技术，获得了初步的实验结果。     

用于激光脉冲整形的任意电脉冲产生技术研究(英文)

为了实现整形脉冲调节的智能化,用计算机分别控制多个GaAs场效应管栅极偏压,并对场效应管产生的脉冲进行脉冲叠加,以控制整形电脉冲的形状;为提高输出整形脉冲的稳定性并减小触发晃动时间,优化设计了脉冲整形电路,结果表明:脉冲输出幅度1～5 V可调;方波脉冲输出宽度0～3 ns;脉冲前后沿分别为250 ps和350 ps;幅度稳定性:～4%(峰峰值) ;时域调整精度200 ps.     

用于高功率激光脉冲整形的可编程任意波形电脉冲发生器

研制了一种基于GaAs场效应管与超快脉冲信号微带传输的可编程任意波形发生器.它由计算机控制的多路高准确度偏置电压,多个级联的GaAs场效应管基元电路,以及微带脉冲传输线组成．输出电脉冲波形导入LiNbO3集成光波导调制器,经过电光调制获得相应的激光脉冲波形．通过计算机设置各基d元电路中GaAs场效应管栅极偏压,进而控制整形电脉冲的形状,使高功率激光装置前端时域脉冲整形实现远程控制．     

闪耀光栅阵列用于半导体激光器列阵光束整形

介绍了半导体激光器列阵的光束整形理论,设计并制作了由两个闪耀光栅阵列构成的整形光学系统,理论计算表明该系统能将激光器快、慢轴方向的光参数积变为5.7 mm·mrad和8.9 mm·mrad.在整形实验中测得变换后快、慢轴方向的光参数积分别为12 mm·mrad和9.5 mm·mrad,经透镜聚焦后能够实现与芯径200 μm,数值孔径0.22的光纤耦合.     

Study on the Applicability of the Static Distributed Circuit Parameters of Non-uniform Microstrip Lines

The Generalized Transmission Line Equations are employed to analyze the circuit parameters of the microstrip lines. The static distributed capacitances and inductances of non-uniform microstrip lines are extracted. By comparing the differences between the port’s S-parameters respectively obtained by the extracted static circuit parameters using circuit method and by the Method of Moment directly, the applicable frequency range of the extracted static distributed circuit parameters can be found. The results show that the extracted static circuit parameters can be used in a frequency band from DC up to millimeter wave. This work was supported in part by the National Natural Science Foundation of China under grant no. 60471053, and in part by the Program for New Century Excellent Talents in University, MOE, China.     

一种用于电光开关的高速、高压电脉冲的产生

介绍了一种用于电光开关驱动源的高压超快电脉冲产生技术;电路采用级联的雪崩晶体管串和微波传输线结构,输出阻抗50Ω;在50Ω负载情况下,获得脉冲下降时间为1ns、幅度达到5kV、峰值电压为6.4 kV、幅度和半宽度稳定性优于2％、触发晃动为±15ps、触发延时为30 ns,脉冲峰值电流为128 A的高压高速大电流脉冲.     

A Continuously Tunable Erbium-Doped Fibre Laser Using Tunable Fibre Bragg Gratings and Optical Circulator

A continuously tunable erbium-doped fibre laser （TEDFL） based on tunable fibre Bragger grating （TFBG） and a three-port optical circulator （OC） is proposed and demonstrated. The OC acts as a 100%-reflective mirror. A strain-induced uniform fibre Bragger grating （FBG） which functions as a partial-reflecting mirror is implemented in the linear cavity. By applying axial strain onto the TFBG, a continuously tunable lazing output can be realized. The wavelength tuning range covers approximately 7.00nm in C band （from 1543.6161 to 1550.3307nm）. The side mode suppression ratio （SMSR） is better than 50 dB, and the 3 dB bandwidth of the laser is less than 0.01 nm. Moreover, an array waveguide grating （AWG） is inserted into the cavity for wavelength preselecting, and a 50 km transmission experiment was performed using our TEDFL at a 10 Gb/s modulation rate.     

A Novel Parallel-Series Feeding Network of Microstrip Patch Arrays with Composite Right/Left-Handed Transmission Line for Millimeter Wave Applications*

A novel parallel-series feeding network of microstrip patch arrays with composite right/left-handed transmission line (CRLH-TL) for millimeter wave applications is proposed. Since there is no inserting phase shift in the patch elements with CRLH-TL feeding structure, the inherent pattern shift resulting from the traditional parallel-series feeding network is removed. Besides, because of the simpler structure and the shorter length of the CRLH-TL feeding network, the antenna array is of higher gain than that with the conventional parallel feeding network.* Supported by the National Natural Science Foundation of China (No. 60371010) and (No. 60471037)     

Characteristics of Wavelength Tunable Femtosecond Soliton Pulse Generation Using Femtosecond Pump Laser and Polarization Maintaining Fiber

We have investigated both experimentally and numerically the characteristics of wavelength tunable femtosecond soliton pulse generation using a pulse width variable fiber laser and two different types of polarization maintaining fibers. The generated soliton shows the feature of the pulsewidth becoming almost constant at - 250 fs under any conditions of the pump pulse for 220m fiber. High conversion efficiency from pump pulse to a generated soliton pulse accounting for as much as 73% can be obtained. This efficiency decreases with increase in the input power or wavelength shift. A superior conversion efficiency and broad wavelength shift can be obtained by using a more shortened pump pulse. In the numerical calculations, it is predicted that under a condition of constant power of pump pulse, the maximum wavelength shift is achieved when the soliton number N is -1.4. The difference of mode field diameter and the group velocity dispersion (GVD) coefficient β₂ affect the wavelength shift and conversion efficiency. Using the fiber with small mode field diameter and small absolute value of GVD coefficient β₂, a high conversion efficiency and large wavelength shift can be obtained.     

基于传输线理论电力高频脉冲在电缆上的传输与反射研究

针对电力高频脉冲在电缆上传输过程引起产生谐波等问题,基于传输线理论,在建立高频脉冲作用下电缆分布参数模型的基础上,探讨在高频脉冲驱动下长电缆传输产生的负面效应问题.论文结合三相交—直—交PWM变换电路带电动机负载状态下,较详细地分析讨论了PWM脉冲波在电缆上的传输和反射过程,研究电机端过电压的产生机理,分析引起电机定子绕组绝缘过早损坏,供电电源电压产生谐波的原因,并通过实验验证了理论分析的有效性.     

传输线负载在高压快速脉冲电路中的应用及分析

提出了一种改良雪崩晶体管大幅度超快速脉冲形成电路性能的方法--传输线负载法.其实质是在传统电路基础上引入传输线微元,并结合阻抗匹配以及信号反射等相关理论,达到大幅度改善后沿特性的目的.通过传统电容负载法与新的传输线负载法的理论分析、仿真计算与实验结果比较表明,传输线负载法可以在保持优良前沿特性的同时,弥补现有电容负载法的不足,大幅改善脉冲后沿特性,并实现脉冲宽度的步进可控.该方法的提出,对于激光脉冲以及高速转镜式相机同步传感等研究有参考意义.     

单模锥形光纤锥区光场及超短脉冲的传输特性

根据光波导理论,采用数值方法分析了单模锥形光纤锥区传输常数和光场分布的变化情况.采用分步傅里叶法数值求解广义的非线性薛定谔方程,对超短脉冲在锥区的传输演化进行了研究.结果表明:传输常数沿拉锥方向缓慢减小,在拉锥末端迅速减小;在拉锥初始阶段,能量主要集中在纤芯中,"转换点"之后能量在纤芯和包层中重新分布,光强在拉锥末端变强;脉宽小于80 fs的超短脉冲沿锥区传输时,沿拉锥方向,脉冲不断展宽,而当脉宽大于80 fs时,脉冲展宽不明显.     

单模锥形光纤锥区光场及超短脉冲的传输特性

根据光波导理论,采用数值方法分析了单模锥形光纤锥区传输常数和光场分布的变化情况.采用分步傅里叶法数值求解广义的非线性薛定谔方程,对超短脉冲在锥区的传输演化进行了研究.结果表明:传输常数沿拉锥方向缓慢减小,在拉锥末端迅速减小|在拉锥初始阶段,能量主要集中在纤芯中,“转换点”之后能量在纤芯和包层中重新分布,光强在拉锥末端变强|脉宽小于80 fs的超短脉冲沿锥区传输时,沿拉锥方向,脉冲不断展宽,而当脉宽大于80 fs时,脉冲展宽不明显.     

利用相位共轭与色散配置实现具有大占空比和大放大器间隔的长距离光孤子传输

在用光纤放大器补偿损耗的光纤传输线中，用负色散光纤与正色散光纤或色散补偿器件交叉配置，并使传输线中光纤的有效色散适当大于（与平均孤子对应的）理论值，同时在传输线中周期地使用相位共轭器，可以在把放大器间隔提高到与常规光纤通信相同的条件下有效地削弱孤子之间的互作用。本文对实现速率为２５Ｇｂｉｔ／ｓ、占空比为１／２、光放大器间隔为１００ｋｍ、传输距离大于６０００ｋｍ的光孤子传输作出了数值论证