A photoconductive switch and optical transconductance varistor having a photoconductive region e.g. a wide bandgap semiconductor material substrate between opposing electrodes. An optical waveguide is arranged to surround the photoconductive region for directing conduction-inducing radiation into the photoconductive region. And an optical diffusion element is arranged to diffuse/disperse the radiation prior to entering the optical waveguide and into the substrate, for uniformly illuminating the substrate for conduction.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 The United States Government has rights in this invention pursuant to Contract No. DE-AC52-07NA27344 between the United States Department of Energy and Lawrence Livermore National Security, LLC for the operation of Lawrence Livermore National Laboratory.