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1、摘 要 i用光电导开关产生稳幅无晃动 超快电脉冲的研究 学科名称 物理电子学 作者姓名 马德明 作者签名 导师姓名 施 卫 教授 导师签名 答辩日期 2005.3 摘 要 本文在借鉴 SI-GaAs 光电导开关研究成果的基础上 结合国家高技术研究发展计划863 计划课题高电压无晃动光电导高速开关关键技术研究No863-804-2002AA842211和国家自然科学基金课题大功率超快电脉冲ps光电导开关微波源的研究No50077017针对超快精同步控制应用的实际要求采用了理论分析和实验研究相结合的方法 开展了对光电导开关产生稳幅无晃动超快电脉冲的研究取得如下成果和结论 1. 光电导开关的超快特性
2、主要由触发光脉冲脉宽和开关芯片材料载流子复合寿命决定减小触发光脉冲脉宽可以改善输出电脉冲的上升沿而选择载流子复合寿命小的开关芯片材料可以减小输出电脉冲的下降沿 通过对触发光脉冲和开关芯片材料的合理选择可以获得超快电脉冲 2. 实验结果还表明光电导开关输出电脉冲的脉冲宽度同时还与触发光脉冲能量和开关偏置电压有关减小触发光脉冲能量增加偏置电压可以在一定程度上减小输出电脉冲的脉冲宽度理论上对这一实验现象作了合理的解释 3. 光电导开关输出电压的大小在外电路一定的条件下主要由偏置电压决定同时开关芯片材料 开关电极间隙宽度以及触发光脉冲能量也会对其产生一定的影响通过合理选择触发条件和优化设计开关可以获得
3、一定幅值大小的超快电脉冲 4. 理论和实验结果表明光电导开关工作在饱和状态下具有稳幅特性减小西安理工大学硕士学位论文 ii开关电极间隙宽度增大触发光脉冲能量可以获得幅值稳定不随触发能量波动而变化的超快电脉冲 5. 光电导开关对光信号具有 ps 量级的响应速度使得其触发晃动时间在 ps量级理论分析认为这是由半导体芯片材料参数所决定的通过选择合适的开关芯片材料参数可以获得 ps 量级晃动的超快电脉冲 6. 利用具有全固态绝缘结构的横向型半绝缘 GaAs 光电导开关分别在 nsps和 fs 超快激光脉冲触发下测试其超快特性和输出电压幅值的稳定性 实验中得到了触发晃动时间无法分辨 幅值变化小于 1.2
4、%的稳定超快电脉冲和上升沿为 83ps 脉冲宽度为 133ps 的超快电脉冲从而为超快精同步控制应用提供了依据 关键词光电导开关 超快电脉冲 电压幅值稳定性 时间晃动 本研究得到国家高技术研究发展计划863 计划课题高电压无晃动光电导高速开关关键技术研究No863-804-2002AA842211和国家自然科学基金课题大功率超快电脉冲ps光电导开关微波源的研究No50077017的资助 Abstract IGENERATION OF STEADY AND JITTER-FREE ULTRA-FAST ELECTRICAL PULSES WITH PHOTOCONDUCTIVE SWITCHES
5、 Subject: Physical electronics Author: Ma De-ming signature: Advisor: Prof. Shi Wei signature: Date: Mar. 2005 Abstract Based on the research results of SI-GaAs photoconductive switches, combined with the Project supported by the National High Technology Development Program of China (Grant No. 863-8
6、04-2002AA842211) and the National Natural Science Foundation of China (Grant No. 50077017), according to the need of switches with ultra-fast, accurate and synchronous control, combined the theory analysis with experiment, the paper studies the characteristics of the stability of pulse voltage ampli
7、tude, jitter-time ultra-fast electrical pulse from photoconductive switches. The main results obtained are as follows: 1. The ultra-fast characteristics of photoconductive switches were mainly determined by the optical pulse width and the carrier lifetime of the chip material. The rise time of outpu
8、t electrical pulse can be improved by decreasing the optical pulse width and selecting the chip materials with shorter lifetime can decrease its fall time, so in order to achieve fast switching, the short optical pulse should be used to trigger photoconductive switches and the material of the short
9、carrier lifetime should be chosen. 2. The results also showed that the output electric pulse width from the 西安理工大学硕士学位论文 IIphotoconductive switches was affected by the optical pulse energy and biased voltage, decreasing the optical energy and increasing the biased voltage can reduce the output pulse
10、 width to a certain extent. The reason was examined. 3. When the exterior circuit was certain, the output voltage was mainly determined by the biased, but it was also affected by the chip materials, the gap length on the device resistance and the optical pulse energy to a certain extent. The ultra-f
11、ast electric pulse with certain voltage amplitude can be obtained by controlling switch trigger condition and optimizing switch design. 4. The theory and experiment results showed that the electric pulse with steady voltage amplitude could be outputted when the photoconductive switches worked in the
12、 saturated situation. Decreasing the gap length on the device resistance or increasing the optical pulse energy can produce the ultra-fast electric pulse with steady voltage amplitude, which is not related to the change of the optical energy. 5. The photoconductive switches responded to the optical
13、signal with pico-second rate so that it can kept the pico-second triggered jitter-time. The theory analysis results indicated the characteristic was determined by the parameters of the chip materials, so in order to obtain the ultra-fast electrical pulse with pico-second jitter-time, the proper para
14、meters should be chosen. 6. The ultra-fast and steady voltage amplitude characteristics of output electrical pulse from the lateral photoconductive semiconductor switches, which were fabricated with SI-GaAs by all solid insulation protection and triggered by nanosecond, pico-second and femto-second
15、laser pulse, were studied. The steady ultra-fast electric pulse, whose change of amplitude was less than 1.2% and the triggered jitter-time was difficulty to discern, and the ultra-fast electric pulse whose pulse width was 133ps and the rise time was 83ps were obtained in the experiment. The result
16、will provide information for realizing the application of the ultra-fast, accurate and synchronous control. Abstract IIIKey words: photoconductive switches, ultra-fast electrical pulse, stability of pulse voltage amplitude, jitter-time. Note: The study was supported by the National High Technology Development Program of China (Grant No. 863-804-2002AA842211) and the National Natural Science Foundation of
