Picosecond signal recovery of type II tunneling bi-quantum-well etalon in all-optical gate operation

We demonstrate picosecond signal recovery in all optical gate operation using a type II tunneling bi-quantum well (TBQ) etalon. Type II TBQ consists of a series of GaAs wells, AlGaAs barriers, and AlAs layers. The recovery time from excitonic absorption bleaching in GaAs wells is governed by tunneling of electrons out of the well through AlGaAs barriers into AlAs layers. The type-II TBQ etalon with 1.7 nm barriers shows 17 ps-recovery.