Research On Optical Quenching/Electric Regulation Of High Gain Mode Of GaAs Photoconductive Semiconductor Switch

High power high repetition rate of ultrafast electrical pulses technology is the basis of a series of high-tech research and cutting-edge research.It has a wide range of applications in communication,radar,electronic countermeasures,electromagnetic weapons,nuclear simulation,laser fusion,environmental protection,food preservation,material modification and other fields.Concerning the power and ultrashort pulse width of high repetition frequency electric pulses,Gallium arsenide photoconductive semiconductor switch(GaAs PCSS)is considered as the most potential ultrafast switches device for its outstanding performances.In viewing of the key requirements of the high repetition rates applications,the linear operating mode and nonlinear(high gain,HG)operating mode have their advantages and shortages,respectively.The linear GaAs PCSS can generate the electric pulses that are comparable of the excitation laser and operate in high repetition rates with long lifetime in which the switching follows the shape of excitation laser.However,the linear mode without avalanche mechanisms needs high power laser,which has big size,expensive cost and limit the further applications.Compared with the linear GaAs PCSS in which only one electron-hole(e-h)pair is generated per absorbed photon,the HG or nonlinear operations can produce as many as 103–105 e-h pairs per absorbed photon because of the avalanche in the GaAs PCSS.It is feasible to replace the desktop laser system with laser diode(LD)sources,which leads to the promise of extremely compact switching systems with low cost.Despite the favorable benefits,the duration of HG operation usually remains from tens nanoseconds to mircoseconds,which are often accompanied by current filaments that would degrade the longevity of device in high repetition rates.In this paper,we proposed to use two delayed optical beams to excite the HG GaAs PCSS to obtain a shorten pulse width,by restraining the transport process of photo-activated charge domain(PACD)within a special suppressed state and quench the non-linear mode.Based on the transport mechanism of photo-activated charges,the experimental setup is designed.The influences of delay time,optical energy,excitation location,storage capacitor on PACD's quenching are investigated,respectively.According to the results we obtained,it indicates that the appropriate delay time between two optical excitation beams can adjust the high avalanche mechanism to a certain extent.Meanwhile,the storage capacitor can control clearly the momentary electric field during the transport of PACD.