Photoconductive semiconductor switches for firing sets and electro-optic modulators

Optically activated GaAs switches operated in their high gain mode are being used or tested for pulsed power applications as diverse as low impedance, high current pulsers, and high impedance, low current Pockels cell or Q switch drivers. These are important to firing sets in munitions, lasers used in detonation of munitions, and lasers used in large weapons effects simulators (such as Jupiter). For firing sets we have switched 2.8 kA at 3 kV DC charge in a very compact package. For driving Q switches, the load is the small (30 pF) capacitance of the Q switch which is charged to 6 kV. We have demonstrated that we can modulate a laser beam with a sub ns risetime. Some aspects of the switches that are relevant to most of these applications are lifetime (longevity), leakage resistance, jitter, and trigger energy. This paper describes the specific project requirements and switch parameters in all of these applications, and emphasize the switch research and development that is being pursued to address the important issues.