Abstract

Optically activated semiconductor opening switches¹ are anticipated to have unique characteristics of repetitive operation, fast opening time, and potential scalability. We have demonstrated the operation of optically activated semiconductors² as fast opening switches. A semiconductor with high dark resistivity is maintained in a conductive state by continuous illumination with argon laser light. The opening of the switch is obtained by interrupting abruptly the light using a Pockels cell placed between two parallel polarizers. The opening speed is given either by the rise time of the Pockels cell (1 ns in our system) or by the recombination time of the carriers optically formed in the semiconductor, whichever is the longest. To demonstrate its operation, the switch was placed in an inductive charging circuit which delivers the stored energy to a load when the switch opens. The shape of the transient current signal was observed on an oscilloscope for different parameters of the circuit and using different switches. The off-to-on resistivity ratio of the switch was always larger than 10³. We have achieved a repetitive 1-ns opening time with an lnGaAs:Fe switch of ~300-ps recombination time. The results obtained with different materials (GaAs, InGaAs, GaAs:Cr) and different gap configurations are presented.

© 1985 Optical Society of America