Semiconductor Selection and Optimization for use in a Laser Induced Pulsed Pico-Second Electromagnetic Source.

摘要

The use of optically induced, d.c. accelerated, semiconductor carriers as a source of picosecond microwave pulses is examined. The purpose of this study was to determine whether 1) phase shifted, multiple (optical) pulses could be generate on a single semiconductor element and 2) whether multiple inline elements could be stimulated with a single optical pulse. Both of the configurations have potential for simultaneously providing the source and phase control necessary for a steerable target recognition array. The efficiency of both techniques are demonstrated in this preliminary study and the gain which could be realized from cooling the semiconductor sources was evaluated for one specimen. Phase differences for multiple pulses were observed and directly related to the special position of the optical pulses with respect to the detector. The cascades sources showed enhanced forward microwave intensity and also an angular dependence consistent with the two sources and detector geometry. Cooling from room temperature to 100k resulted in approximately a three fold improvement in microwave strength (from a single element).