Sensitive optical gating of reverse-biased AlGaAs/GaAs optothyristors for pulsed power switching applications

A heterojunction-based optothyristor has been fabricated and tested with biasing field intensity up to 34 kV/cm for pulsed power applications. The reverse-biased optothyristor can even be triggered by a light-emitting diode (LED) of a few microwatts power, and more than 500 times reduction in the required LED power for triggering has been observed when compared to bulk photoconductive switches. The optothyristor, however, does not turn on under similar triggering conditions if bias polarity is changed. The sensitive optical gating of the reverse-biased optothyristor is explained. The turn-on delay time under reverse bias has been found to be inversely proportional to the square root of the LED power. The possibility of improving the switching efficiency by superimposing the laser pulse on a constant lower level background illumination has been demonstrated.>