PICOSECOND OPTICAL SIGNAL RECOVERY IN TUNNELING BI-QUANTUM WELL STRUCTURE

Fast recovery from the excitonic absorption bleaching in tunneling bi-quantum well (TBQ) structures is proposed and demonstrated. The TBQ has a new feature that conventional superlattices will never have; that is, control of the recovery time of optical nonlinearity using tunneling. By reducing the tunneling barrier thickness, the recovery time can be reduced to the picosecond region, which is three orders of magnitude faster than the nanosecond recovery of conventional MQWs. By using type-II TBQs, we have demonstrated all-optical gate operation of a Fabry-Perot etalon. The type-II TBQ etalon with 1.7-nm barriers exhibits a full signal recovery of 17 ps.