Influence Of Transmission Line Energy Storage On Ultra-fast Characteristics Of GaAs Photoconductive Semiconductor Switch

With the application and development of pulse power technology,high-power and narrow pulse has attracted more and more attention,especially the narrow pulse of l-5ns is applied in UWB radar,ground penetrating radar,biomedicine and dielectric wall accelerator.Photoconductive semiconductor switch is one of perfect switches to generate the ultra-short electrical pulse.Compared to the conventional electronic switches,PCSS have the advantages of low trigger jitter,high repetition rate,high-speed response and optical electrical isolation,et al.But the pulse width of the output electrical pulse is often wider than that of the excitation laser on the basis of PCSS,so the shorter laser is always used to trigger the switch,such as the femtosecond laser.The desk laser is not merely expensive,but also bulky,which is not conducive to the commercialization of system.So it has become an important research direction to break through the limitation of the pulse width of the laser.Based on the high power and narrow pulse and compact and cheap development requirements of GaAs photoconductive switch,in this paper,the microstrip line is used to storage energy,and the laser diode triggers the GaAs photoconductive switch,in the high multiplication mode,the ultra-short pulse which is shorter than the triggered light pulse width is produced.In the experiment,the switch entered the high multiplication mode at 5.7kV.When the bias voltage is 8.0kV,the switch outputs electric pulse width is the most narrow reach 956.8ps,amplitude is 2.3kV,among which the pulse width of the trigger light is 41.9ns,the light energy is 4.16μJ,at the same time,ten times of superposition test are carried out when the bias voltage is 8.0kV,the standard deviations of the pulse width and amplitude of the output electric pulses is 157.4ps and 95.1V,respectively.The results show that the switch outputs electric pulse has a good stability.This is the best result obtained by laser diode triggering GaAs photoconductive switch so far,breaking the bottleneck of laser pulse width and making high-power narrow pulse easier to obtain.This rare phenomenon can be well explained by transmission line theory and photoexcited charge domain model.After calculation,the quenching threshold electric field at different bias voltages is 4.2±0.6kV/cm,which is consistent with the threshold voltage of Gunn effect.