Studies On The Techniques Of Nonlinear Photoconductive Semiconductor Switches High Power Ultrashort Pulse Generators

The operational principles of GaAs PCSS's were analyzed theoretically in this paper, with emphasis on the micro-mechanism of nonlinear operational mode. A device model involving the high-field properties and dynamics of deep level traps was developed and simulated numerically, which explain the various phenomena of the nonlinear mode. A new concept of threshold of deep level impurity was proposed according to the simulated results. An opposed electric contact configuration was proposed, and a rectangle, a round-comer quadrangle and Rokowski profile of electric contact were designed in order to improve the characteristics and longevity of PCSS. A general and a high-efficiency ultra-short pulse generators both utilizing microstrip or parallel-plate were designed and fabricated. The method of Laplace transform was applied to analyze the two general pulse generators, and a new method combining space-tune diagram and the method of moments was constructed to analyze the high-efficiency parallel-plate pulse generator. All the fabricated devices were studied experimentally triggered by a laser diode and by a frequency doubled mode-locked picosecond Nd:YAG laser, with various nonlinear outputs of PCSS in these circuits obtained.