ELECTROOPTIC IMAGING OF SURFACE ELECTRIC-FIELDS IN HIGH-POWER PHOTOCONDUCTIVE SWITCHES

A two-dimensional electrooptic probe was used to image the electric field in high-power photoconductive switches during switch operation. A LiTaO3 crystal, covering the entire active area of the photoconductive switch, coupled the surface electric field with the polarization of an optical probe pulse. The optical probe was imaged onto a two-dimensional detector array, producing snapshots of the surface field with 200-ps time resolution and 3-pm spatial resolution. The probe system was used to monitor the electric field in the electrode gap of high-voltage switches, the focus of investigation being the collapse of the electric field in a GaAs bulk switch as it was switched with a X = 1.06 μm optical pulse. The switching speed and generation of field enhancements were found to be dependent on the ilumination configuration and the applied electric field, which varied from 0 to 15 kV/cm. Switching efficiency was found to decrease with increasing field. © 1990 IEEE