线性模式下GaAs光电导开关的时间抖动特性

Time jitter characteristics of GaAs photoconductive semiconductor switch in linear mode

针对线性模式下GaAs光电导开关时间抖动特性的研究,对提高精密同步控制系统的输出性能具有重要意义.根据电脉冲的概率分布和时间与电脉冲波形的对应关系,结合载流子的输运过程,对光电导开关时间抖动进行了定性的理论推导.此外,通过搭建实验平台,利用正交光栅分光,将一束激光同时触发两路并联的GaAs光电导开关,改变触发激光脉冲宽度及外加偏置电压测试开关时间抖动,根据实验值的对比分析,得出在不同的外加偏置电压下,随着触发激光脉冲宽度的减小,开关时间抖动值随之减小.验证了触发激光脉冲宽度对开关时间抖动的影响及理论分析的正确性.研究结果对GaAs光电导开关时间抖动的进一步减小具有一定的指导意义.

Time precision switching is crucial to a high-precision synchronization control system with several synchronized sources. Compared with the other high-power switches, a Ga As photoconductive semiconductor switch（PCSS） with a litter time jitter has been widely used in a precision synchronization control system. There is little work on the time jitter of a Ga As PCSS. In this paper, a formula of Ga As PCSS time jitter is derived by the qualitative theoretical derivation through using the probability distribution of the output electrical pulse and the corresponding relation between the time and electrical waveform of Ga As PCSS, and combining the carrier transport process. In experiment, a neodymium-doped yttrium aluminum garnet nanosecond laser beam is split by a semipermeable half mirror into two optical beams, and then these two beams simultaneously trigger two identical Ga As PCSSs in two parallel circuits. As the energy of a triggering laser pulse is fixed at 0.35 m J, four different laser pulse widths, namely 30 ns, 22 ns, 16 ns and 11 ns, respectively, are used to trigger the Ga As PCSSs. The bias voltage changes from 0.1 kV to 1 kV in steps of 0.1 kV, and it is used in the above-mentioned experiment. The PCSSs are triggered 20 times at each of the bias voltage values. The time jitter of the Ga As PCSS with a 3-mm gap can be measured. By analyzing the experimental data, we conclude that the time jitter of the Ga As PCSS decreases with the triggering laser pulse width decreasing under the condition of different bias voltage.In the linear mode, the Ga As PCSS illuminated by a photon with a proper wavelength creates an electron-hole pair. The characteristic of the triggering laser pulse determines that of the output electrical pulse. With the energy of triggering laser pulse fixed, the fluctuation of electrical pulse increases fast with its pulse width decreasing. Moreover, according to the derived formula for a time jitter, the Ga As PCSS time jitter decreases with triggering laser pulse width narrowing,under the different externally applied bias voltages. It is demonstrated that the theoretical and experimental results of the relationship between the triggering laser pulse width and the Ga As PCSS time jitter are consistent. The obtained results provide a basis for further reducing the Ga As PCSS time jitter, which is important for a next-generation fusion research facility and laser trigger antenna array of generating short pulse sequence.