BISTABLE OPTICALLY CONTROLLED SEMICONDUCTOR SWITCHES IN A FREQUENCY-AGILE RF SOURCE

The processes of persistent photoconductivity followed by photoquenchi ng have been demonstrated at megawatt power levels in copper-compensat ed, silicon-doped, semi-insulating gallium arsenide, These processes a llow a photoconductive switch to be developed that can be closed by th e application of one laser pulse (lambda = 1.06 mu m) and opened by th e application of a second laser pulse with a wavelength equal to twice that of the first laser (lambda = 2.13 mu m). This switch is called t he bistable optically controlled semiconductor switch (BOSS), The open ing phase of the BOSS requires a sufficient concentration of recombina tion centers (RC) in the material for opening to occur in the subnanos econd regime. These RC's are generated in the bulk GaAs material by fa st-neutron irradiation (similar to 1 MeV). Neutron-irridated BOSS devi ces have been opened against a rising average electric field of about 36 kV/cm (18 kV) in a time less than 1 ns while operating at a repetit ion rate, within a two-pulse burst, of about 1 GHz. The ability to mod ify the frequency content of the electrical pulses, by varying the tim e separation, is demonstrated, Results demonstrating the operation of two BOSS devices imbedded in a frequency-agile RF source configuration are also discussed.