光时分复用(OTDM)系统中基于电吸收调制器(EAM)的短脉冲光源及解复用器的设计考虑

研究了电吸收调制器(EAM)的衰减随外加反向电压增加而指数增加的情形下,短脉冲光源的脉冲输出和解复用器的开关窗口对EAM的消光效率、反向DC偏置电压以及正弦RF驱动信号的幅度等参量的依赖关系.在基于EAM的短脉冲光源中,输出脉冲的消光比等于EAM消光效率η与正弦驱动电压峰峰值V_pp的乘积,输出光脉冲的消光比和脉宽均与EAM的反向偏置电压无关,但输出脉冲的峰值功率与η、V_pp和V_b都有关系.在基于EAM的解复用器中,为了使解复用器的开关窗口近似为矩形,可利用EAM的削波效应,使V_pp/2>V_b.在EAM的消光效率η已知时,通过仔细设计反向DC偏置电压V_b和正弦驱动电压的峰峰值V_pp,达到OTDM解复用器所需要的开关窗口形状、宽度和消光比.     

基于电吸收调制器的解复用器窗口特性分析及优化

数值模拟了基于电吸收调制器 (Electro absorptionmodulator,EAM)解复用器的开关窗口特性 ,在考虑邻道串扰和强度抖动 (由同步偏离和时间抖动导致 )的光时分复用数值模型中对解复用信号的误码率进行分析。数值模拟结果表明 ,电吸收调制器的窗口特性 (消光比和窗口宽度 )满足 4× 10Gb/s的光时分复用通信系统中解复用器的要求 ;在小的偏置电压下 ,邻道串扰和解复用器的透过率特性必须仔细考虑以达到最小的误码率 ;在大的偏置电压下 ,较大的射频幅度将会使解复用信号误码率最小     

具有皮秒量级开关窗口的光波导微环谐振器

提出一种可以产生皮秒量级开关窗口的光波导微环谐振器,对其设计与性能进行了分析和研究。采用多环层叠结构来设计微环谐振器的传输特性曲线,利用特性曲线的非线性特征,在正弦电压的作用下改变材料的折射率可获得一个较窄的开关窗口。采用耦合矩阵理论研究了系统的调制特性以及开关窗口特性,分析了开关窗口宽度和消光比与驱动电压的关系。研究结果表明,10 GHz驱动电压情况下,开关窗口宽度、消光比和插入损耗可以分别优于10 ps,40 dB和1 dB。只需要电的控制信号而无需高质量的光控制脉冲,且具有工作速率高、结构简单、消光比高、传输损耗小和工作电压低等特点。     

对称半导体光放大器马赫—曾德尔干涉仪解复用器的开关特性分析

分析以以半导体光放大器（SOA）为基础的对称马赫－曾德尔干涉仪（MZI）解复用器在控制脉冲和信号脉冲反向传播（CPMZ）与同向传播（TPMZ）两种工作模式下的开关特性。研究表明：控制脉冲宽度、半导体光放大器的长度和非线性增益压缩影响着控制脉冲和信号脉冲反向传播开关窗口的大小，是限制控制脉冲和信号脉冲反向传播高速工作的主要因素。当控制脉冲宽度小于半导体光放大器的渡越时间时，如时延量小于于两位的半导体光放大器渡越时间，控制脉冲和信号脉冲以向传播的峰值开关比开始恶化；当控制脉冲宽度超过半导体光放大器的渡越时间时，即使时延量大于两倍的半导体光放大器滤越时间，峰值开关比也出现恶化。因此当控制脉冲和信号脉冲反向传播高速工作时，控制脉冲应尽可能窄，且时延量必须大于两倍的半导体光放大器渡越时间以确保有较高的峰值开关比，而半导体光放大器长度效应对控制脉冲和信号脉冲同向传播的影响甚微。     

对称半导体光放大器马赫曾德尔干涉仪解复用器的开关特性分析

分析了以半导体光放大器 (SOA)为基础的对称马赫 -曾德尔干涉仪 (MZI)解复用器在控制脉冲和信号脉冲反向传播 (CPMZ)与同向传播 (TPMZ)两种工作模式下的开关特性。研究表明 :控制脉冲宽度、半导体光放大器的长度和非线性增益压缩影响着控制脉冲和信号脉冲反向传播开关窗口的大小 ,是限制控制脉冲和信号脉冲反向传播高速工作的主要因素。当控制脉冲宽度小于半导体光放大器的渡越时间时 ,如时延量小于于两倍的半导体光放大器渡越时间 ,控制脉冲和信号脉冲反向传播的峰值开关比开始恶化 ;当控制脉冲宽度超过半导体光放大器的渡越时间时 ,即使时延量大于两倍的半导体光放大器渡越时间 ,峰值开关比也出现恶化。因此当控制脉冲和信号脉冲反向传播高速工作时 ,控制脉冲应尽可能窄 ,且时延量必须大于两倍的半导体光放大器渡越时间以确保有较高的峰值开关比。而半导体光放大器长度效应对控制脉冲和信号脉冲同向传播的影响甚微     

基于电吸收调制晶体(EAM)的超短光脉冲特性研究

数值模拟了两种形式的基于电吸收调制晶体(EAM)的超短光脉冲源(单EAM)和级联EAM形式)的输出脉冲宽度及消光比与外加反向偏压、射频信号幅度之间的变化关系.数值模拟结果表明,在重复率为10GHz情况下,对于单EAM形式,可以获得的最小脉宽大约为13ps,其消光比大于20dB,脉冲波型接近sech2孤子波型;对于级联EAM形式,我们得到了小于5ps的超短脉冲,消光比也较单EAM形式有较大的提高.因此,单EAM形式的超短脉冲源可以满足20Gb/s的OTDM系统需求,也同样适合于超长距离的光孤子通信系统;级联形式EAM可以满足40Gb/s的OTDM系统光源需求.     

带反偏置的双路高压脉冲电源的研究

通过调节反向偏置电压可以改善电场渗透对质谱仪的影响,提高质谱仪的分辨率。为了满足质谱仪对脉冲电场的不同要求,提出了一种可以同时输出两路极性相反脉冲电场的脉冲电源,且高压正脉冲叠加幅值可调的直流负偏置电压。该电源只需一个充电源便可以产生正负两路脉冲电场。分析了串联开关同步驱动效果,随后通过增加补偿绕组和并联电阻优化了串联电容的分压不均的问题,并验证一个磁芯加多个副边绕组的方案可进一步降低充电电压不均。最终实现了4个电容器的充电电压与平均电压相差不超过0.1%。搭建了一台4级的电源样机,实验表明,其可以在容性负载上产生一路幅值为0～1.5 kV、脉宽为2～10μs可调的高压正脉冲且叠加幅值为0～-200 V的反向偏置电压,和一路幅值为0～-1.5 kV、脉宽为2～10μs可调的高压负脉冲,频率高达10 kHz,正负脉冲的前沿均小于30 ns,脉冲波形平稳。该脉冲电源结构紧凑,并且输出电压、脉宽、频率均连续可调。     

基于DSRD的高重频固态脉冲源的研制

介绍了一种基于新型高功率超高速半导体断路开关—漂移阶跃恢复二极管(DSRD)和可饱和脉冲变压器的高电压高重频超高速全固态脉冲源。设计了脉冲源的电路拓扑结构,理论上分析了脉冲源电路的工作原理,研究获得了可饱和脉冲变压器匝数、磁芯截面积及负载阻抗等参数对脉冲源输出特性的影响的规律。实验结果表明:脉冲源在50 kΩ阻性负载条件下,输出脉冲峰值电压约38.2 kV,脉冲前沿约7.1 ns,脉冲宽度约14.1 ns,输出峰值功率约29.2 kW,可在400 kHz重复频率下稳定工作。     

用于长脉冲大功率微波系统的高压调制电源

为ＨＬ－１Ｍ装置上的ＬＨＣＤ和ＥＣＲＨ长脉冲大功率微波系统研制的主调制电源,已达到了－７０ＫＶ、３５Ａ的输出指标。应用该电源首次实现了ＴＭ－７０３Ｆ型大功率调整管在１ｓ长脉冲下的运行和双大功率高压调制器的并联运行,在没有ＣＲＯＷＢＡＳＲ保护系统的情况下采用有效的快速保护措施实现了长期的稳定可靠运行。     

基于窄脉冲传输的脉冲展宽IGBT驱动电路

设计了一种采用高压隔离脉冲变压器传输窄脉冲,然后应用脉冲展宽电路实现宽脉冲驱动信号输出的无源IGBT驱动电路。采用正电压turn-on窄脉冲和负电压turn-off窄脉冲组合传输的方式以减小高压隔离脉冲变压器的体积和重量,脉冲展宽电路使IGBT在turn-on脉冲上升沿导通,在turn-off脉冲上升沿关断,且其具备储能功能,无需高压隔离辅助直流电源为其供电。脉冲信号发生电路和过流保护电路耦合设计,使IGBT在正常关断和过流保护关断情况下,其栅极都处于反压偏置状态,以提高IGBT关断的快速性和可靠性。将驱动电路用于级联Marx高压电路中IGBT开关的驱动,turn-on脉冲和turn-off脉冲的脉宽均选择为2 μs,结果表明,Marx电路在输出脉冲电压峰值为20 kV时工作稳定,且脉宽在3.5~50 μs之间连续可调,等离子体负载下的输出电压和电流波形显示,打火情况发生时,过流保护电路工作稳定可靠。该驱动电路可有效实现宽脉冲驱动信号的产生,具有较强的可靠性和实用性。     

Optimized performance map of an EAM for pulse generation and demultiplexing via FROG characterization

We demonstrate the complete characterization of a sinusoidally driven electro-absorption modulator (EAM) over a range of RF drive voltages and reverse bias conditions. An accurate performance map for the EAM, to be employed as a pulse generator and demultiplexer in an optical time division multiplexed (OTDM) system, can be realized by employing the Frequency Resolved Optical Gating technique. The generated pulses were characterized for chirp, extinction ratio (ER) and pulse width (<4 ps). The optimization of the EAM’s drive conditions is important to ensure that the generated pulses have the required spectral and temporal characteristics to be used in high-speed systems. The ER and pulse width also influence the demultiplexing performance of an EAM in an OTDM system. This is confirmed by utilizing the EAM as a demultiplexer in an 80 Gb/s OTDM system and measuring the BER as a function of the received optical power for various values of the ER and pulse width. It is of paramount importance to accurately characterize the performance of each individual EAM as the modulators characteristics are device dependant, thus optimum performance can be achieved with slight variations to the device’s drive conditions. By employing FROG, an optimum performance map of each specific device can be deduced. Simulations carried out verified the experimental results achieved.     

Analysis of optical time domain demultiplexer using microring resonators

A time domain optical demultiplexer using electrooptic microring resonator is proposed. The switching window with pico-second order width is generated by using a sinusoidal electrical control voltage to shift the refractive index of the material. The modulation characteristics and switching window of the microring resonator are studied. The dependences of the width and extinction ratio of the switching window on the control voltage are analyzed. The demultiplexing performance of a 40–10 Gbps system is evaluated by numerical simulation technology. Results show that switching windows with required width and extinction ratio can be generated.     

High repetition rate optical switch using an electroabsorption modulator in TOAD configuration

A novel optical switch featured with high repetition rate, short switching window width, and high contrast ratio is proposed and demonstrated for the first time by placing an electroabsorption modulator (EAM) in a terahertz optical asymmetric demultiplexer (TOAD) configuration. The feasibility and main characteristics of the switch are investigated by numerical simulations and experiments. With this EAM-based TOAD, an error-free return-to-zero signal wavelength conversion with 0.62 dB power penalty at 20 Gbit/s is demonstrated.     

Demonstration of an 8×10-Gb/s OTDM system

An 8×10 Gb/s optical time-division-multiplexing (OTDM) system was demonstrated with an electroabsorption modulator (EAM) based short pulse generator followed by a two-stage nonlinear compression scheme which generated stable 10-GHz, 2-ps full-width at half-maximum (FWHM) pulse train, an optoelectronic oscillator (OEO) that extracted 10-GHz clock with a timing jitter of 300 fs from 80-Gb/s OTDM signal and a self cascaded EAM which produced a switching window of about 10 ps. A back-to-back error free demultiplexing experiment with a power penalty of 3.25 dB was carried out to verify the system performance.     

Optimizing the performance of TOAD by changing the wavelength and power of control pulse

The performance of terahertz optical asymmetric demultiplexer (TOAD) has been studied by modelling the semiconductor optical amplifier (SOA) in which the intraband effects had been taken into account. Numerical results are coincident with the experiment results. We interpret why there are three peaks in the switching window, which has never been reported before. In addition, we put forward the definition of the flatness of the switching window of TOAD for the first time By analysing the different phase of clockwise and counter clockwise signal pulse changed by SOA, appropriate peak power of control pulse and wavelength of signal and control pulse have been calculated in order to obtain large output power and flat switching window of TOAD.     

Gbit/s rate bipolar pulse modulation of semiconductor injection lasers

Using a bipolar drive current pulse shape and very low threshold (9 mA) lasers, zero-background pseudorandom optical pulses were generated and detected at a rate of up to 4 Gbit/s without a pattern effect. The drive current pulse consists of a forward pulse followed by a reverse pulse, each of 70 ps duration and about 400 mA amplitude. No DC bias was applied, which is a necessary condition for pattern-effect-free modulation.     

超低压选择区域生长法制备产生10GHz重复率超短光脉冲的级联电吸收调制器与分布反馈激光器单片集成光源

采用超低压(22×１０^２Pa)选择区域生长(selective area growth, SAG)金属有机化学气相沉积(metal-organic chemical vapor deposition, MOCVD)技术成功制备了InGaAsP/InGaAsP 级联电吸收调制器(electroabsorption modulator, EAM)与分布反馈激光器(distributed feedback laser, DFB)单片集成光源的新型光电器件.实验结果表明，采用该技术制备的器件 关键词： 超低压 选择区域生长 集成光电子器件 超短光脉冲     

Analyzing the Switching Characteristics of a NOLM Demultiplexer with on Analytic and Numrical Methods

1IntroduCtionAllopticalswitchesarekeycOrnpoentsinfuturehigh-speedOPticaltimediVisi0nmultiPleking(0TDM),yst.ms[i].Asasort0fall-OPticalsWtchingdevices,nonllnear0Pticalboharrors(NOLMs)areverysultablef0rall-0PticaldemultiplexinginultrahighsPeedOTDMsystemsbecause0ftheirsimPleconfiguratdri,stableandreliableperformance,andultrafastresP0ndingspeed['J.HOWever,asN0LMutilizestheinherentnonlinearity(crossphasemodulation:XPM)0ffibertoperf0rmswttching,weaknonlineareffects0ffibercausethatl0nger…