Photoconductive, semiconductor switch technology for short pulse electromagnetics and lasers

Abstract

High gain photoconductive semiconductor switches (PCSS) are being used to produce high power electromagnetic pulses for: (1) compact, repetitive accelerators; (2) ultra-wide band impulse sources; (3) precision gas switch triggers; (4) optically-activated firesets; and (5) high power optical pulse generation and control. High power, sub-nanosecond optical pulses are used for active optical sensors such as compact optical radars and range-gated/ballistic imaging systems. Following a brief introduction to high gain PCSS and its general applications, this paper focuses on PCSS for optical pulse generation and control. PCSS technology can be employed in three distinct approaches to optical pulse generation and control: (1) short pulse carrier injection to induce gain-switching in semiconductor lasers; (2) electro-optical Q-switching; and (3) optically activated Q-switching. The most significant PCSS issues for these applications are switch rise time, jitter and longevity. This paper describes both the requirements of these applications and the most recent results from PCSS technology. Experiments to understand and expand the limitations of high gain PCSS are also described.