Optical triggering of a trapped plasma

Dense electron-hole pairs trapped in a semiconductor p+-n-n+ structure form a trapped plasma that can conventionally be triggered by applying an overdriven electrical field to initiate impact ionisation. A new optical triggering mode is presented, which uses short light pulses at an electrical field just below the critical level. The optically generated carriers are separated by the applied electrical field and locally raise the electrical field which excites the impact ionisation. The letter describes the physical properties of the triggering process and the results of a one-dimensional computer simulation.