皮秒激光脉冲触发下光电导开关响应时间的理论计算

本文采用计算机数值分析的方法,分析了激光脉冲的能量、宽度、半导体对光的吸收系数、半导体的表面复合、体复合以及俄歇复合等因素对光电导开关响应时间的影响。结果表明,光电导开关的响应虽然很快,但与光脉冲并不完全同步,而有一个短的时间滞后。     

触发光脉冲对光电导开关响应速度的影响

实验测试了触发光脉冲对光电导开关响应速度的影响;建立了满足光导开关触发光脉冲参量的光生载流子速率方程,并模拟出光生载流子浓度随触发光脉冲、脉冲宽度的变化规律,分析了光脉冲对光电导开关响应速度的影响及引起输出电脉冲上升沿变化的原因.     

基于光电导开关的高功率超宽带微波脉冲产生技术

光控光电导开关因其具有传统高功率脉冲器件所不具有的优良特性 ,在产生高功率微波脉冲领域具有很大的发展潜力。利用光控光电导开关可以直接从直流电源产生高功率的微波脉冲。本文首先介绍了光控光电导开关的结构和两种不同的工作模式 ,以及它在不同工作模式下的工作特性 ,然后叙述了利用光控光电导开关产生高功率超宽带微波的几种技术     

半绝缘GaAs光电导开关亚皮秒传输特性的研究

 本文应用Ensemble-Monte Carlo方法模拟了半绝缘GaAs(SI-GaAs)光电导开关基于Auston等效电路亚皮秒传输特性.从载流子在开关体内的动态特性出发,研究了光电导开关在飞秒激光脉冲触发下光电导传输特性、电介质弛豫特性、开关储能特性以及开关工作模式;分析了非线性光电导开关对光能阈值和偏置电场阈值要求的物理机制.     

利用光电导开关的光电子相关测量

本文在实验的基础上,提出了光电导开关等效时变电导的新表达式。据此分析了光电导开关在高速脉冲的产生和取样以及在光电子相关测量中的特性。分析的结果与实验基本一致,为将来利用光电子相关方法测量电子器件打下了基础。在实验中采用较为简单的工艺,获得光电导开关的上升时间为100ps。相信,只要增加离子轰击处理,上升时间可望达到10ps。     

用1553nm激光脉冲触发GaAs光电导开关的研究

用1553nm飞秒光纤激光器触发半绝缘GaAs光电导开关的实验表明,当光电导开关处于3.33～10.3kV/cm的直流偏置电场并被脉冲宽度200fs且单脉冲能量0.2nJ的激光脉冲照射时,开关表现为线性工作模式,开关输出峰值电压为0.8mV.分析表明,开关对波长为1553nm触发激光脉冲表现出的弱光电导现象起因于半绝缘GaAs材料EL2深能级的作用.     

激光触发GaAs光电导开关非线性现象的实验研究

实验研究了光电导开关的非线性现象,结果表明用半导体激光脉冲串触发光电导开关,在保持激光触发GaAs光电导开关实验条件不变的情况下,产生非线性的电阚值会不断降低.测量和比较试验前后光电导开关暗电阻,初步表明产生非线性的电阈值降低,是光电导开关因光照和产生非线性引起内部材料物理机制发生变化所致.     

光电导开关面临的问题及发展趋势

光电导开关具有传统高功率脉冲器件不具备的优良性能,在产生高功率脉冲领域有很大发展潜力。使用光导开关能直接从直流电源产生电磁脉冲。根据各种应用对光导开关性能指标的不同要求,将其归纳为大功率脉冲应用与超短电磁脉冲应用两类。阐述了光电导开关在理论、实用化方面遇到的问题以及目前学术界、业界对其解决的方法。对各种解决方法做出评价并展望光导开关未来发展趋势。     

一种GaAs快速光电导开关

本文报道了一种采用掺 Cr的 GaAs高阻材料,交叉指状图形,Ni/Ge/Au金属化,浅腐蚀坑改善光电耦合效率的快速、灵敏光电导开关.在染料激光脉冲激励下,获得短于200ps的瞬态响应.根据分析,这种光电导开关的瞬态响应应远小于200 ps,适用于信号处理.     

LT—GaAs飞秒光电导特性

采用飞秒脉冲光电探测技术研究低温生长砷化镓光电导开关超快瞬态响应特性.实验测得不同激发波长或偏置电压下LT-GaAs光电导开关瞬态响应驰豫时间约350～390fs,由实验数据计算得到电子迁移率约1000cm     

Ultrafast pulse generation in photoconductive switches

Carrier and field dynamics in photoconductive switches are investigated by electrooptic sampling and voltage-dependent reflectivity measurements. We show that the nonuniform field distribution due to the two-dimensional nature of coplanar photoconductive switches, in combination with the large difference in the mobilities of holes and electrons, determine the pronounced polarity dependence. Our measurements indicate that the pulse generation mechanism is a rapid voltage breakdown across the photoconductive switch and not a local field breakdown     

用光导开关产生高压、高功率超快电脉冲

基于半导体材料的光导效应,设计并制做光导开关,在偏压为4000V,负载电阻Z0为50Ω时,用脉宽为～12ns的激光脉冲辐照光导开关,得到脉宽为～16ns,峰值电压为～1.8kV,峰值功率为～65kW的电脉冲,本文并对光导开关的技术关键进行了分析。     

Ultrafast photoconductive self-switching of subpicosecondelectrical pulses

A novel photoconductive switch is proposed. The geometry of this ultrafast switch allows the rising edge of an ultrashort optical pulse to both turn on and turn off a terahertz electrical transient, making the device independent of the substrate material and charge carrier lifetime. A lumped-element model is used to analyze the operation of the switch. The model employed describes the photoexcitation of both a microstrip photoconductive switch layout and a coplanar photoconductive switch layout. It is found that both of the layouts are capable of achieving subpicosecond switching, with the coplanar layout offering greater ease of fabrication and device tunability     

四路并联光电开关输出电脉冲性能研究

采用波长为1064 nm的ns脉冲激光器作为触发光源,利用光纤分束同时触发四路并联GaAs光电开关.得到能够得到稳定的电脉冲,任意两路电脉冲的同步精度为48ps,满足实际应用指标.     

半绝缘GaAs光电导开关的光控预击穿特性

用波长1064nm,触发光能为0.5mJ的激光脉冲触发电极间隙为4mm的半绝缘（SI）GaAs光电导开关,当偏置电压达到4kV时,开关并未引发自持放电,而是进入非线性（lock-on）工作模式,即开关处于光控预击穿状态。分析认为：通过激子的产生和离解激子效应贡献了光电导;碰撞电离、雪崩倍增、激子效应补充了因外界光源撤出后所需的载流子浓度和能量。在上述因素的相互作用下,SI-GaAs 光电导开关并没有引发自持放电而是处于光控预击穿状态,丝状电流特性影响着开关的损伤程度。     

用1064nm激光脉冲触发半绝缘GaAs光电导开关的奇特光电导现象

报道了用1064nm激光脉冲触发半绝缘GaAs光电导开关的一种奇特光电导现象.GaAs光电导开关的电极间隙为4mm,当偏置电场分别为2.0和6.0kV/cm时,用脉冲能量为0.8mJ,宽度为5ns的激光触发开关,观察到开关输出的线性和非线性工作模式.当偏置电场增至9.5kV/cm,触发光脉冲能量在0.5～1.0mJ范围时,观察到奇特的光电导现象,开关先输出一个线性电脉冲,经过大约20～250ns时间延迟后,触发光脉冲消失,开关又输出一个非线性电脉冲.这一奇特光电导现象的物理机制与半绝缘GaAs中的反位缺陷和吸收机制有关.分析计算了线性与非线性电脉冲之间的延迟时间,结果与实验观察基本吻合.     

Light controlled prebreakdown characteristics of a semi-insulating GaAs photoconductive switch

A 4 mm gap semi-insulating(SI) GaAs photoconductive switch(PCSS) was triggered by a pulse laser with a wavelength of 1064 nm and a pulse energy of 0.5 mJ.In the experiment,when the bias field was 4 kV, the switch did not induce self-maintained discharge but worked in nonlinear(lock-on) mode.The phenomenon is analyzed as follows:an exciton effect contributes to photoconduction in the generation and dissociation of excitons. Collision ionization,avalanche multiplication and the exciton effect can supply carrier concentration and energy when an outside light source was removed.Under the combined influence of these factors,the SI-GaAs PCSS develops into self-maintained discharge rather than just in the light-controlled prebreakdown status.The characteristics of the filament affect the degree of damage to the switch.     

Photovoltaic Response Characteristics of GaAs Photoconductive Switches Under High Gain Mode

Given is the experiment results in which the laser pulses of 1 046 nm and 532 nm are used to trigger the semi-insulation GaAs photoconductive semiconductor switch（PCSS） with an electrode distance of 4 mm. And made is an analysis of the switch＇s photovoltaic response characteristics under the high gain mode when the biased field is bigger than the Geng effect field. Also a theory is presented that the main reason for the photovoltaic pulse response delay is the transmission of charge domain, caused by the presence of EL2 energy level in the chip material. Finally, the transmission time of charge domain is calculated and a result that inosculates with the experiment is attained.