Sub-nanosecond avalanche transistor drivers for low impedance pulsed power applications

Abstract

Summary form only given. Ultra compact, short pulse, high voltage and current pulsers are needed for a variety of non-linear electrical and optical applications. With a fast rise time and short pulse width, these drivers are capable of producing sub-nanosecond electrical and optical pulses by gain switching semiconductor laser diodes. Gain-switching of laser diodes requires a sub-nanosecond pulser with low output impedance (5 W or less) to generate a fast (<100 ps) optical pulse. The designed pulsers also could be used for triggering photo-conductive semiconductor switches, gating high speed optical imaging systems, and providing electrical and optical sources for fast transient sensor applications. Building on concepts from Lawrence Livermore National Laboratory, the development of pulsers based on solid state avalanche transistors was adapted to low impedances. As each successive stage is avalanched in the circuit, the amount of overvoltage increases, increasing the switching speed and improving the turn on time of the output pulse at the last stage. The output of the pulser is coupled into the load using a parallel plate charge line. The impedance and associated discharge time of this transmission line is tailored to the impedance and pulse duration requirements of the load. With the adapted circuit modifications, we have designed and evaluated a driver pulser capable of delivering 200 V DC into a 5 W load with a 250 ps risetime and a 500 ps pulsewidth. Results from transmission line, resistive, and semiconductor laser diode test loads will be presented.