Picosecond signal recovery in type II tunneling bi-quantum well etalon

We demonstrate picosecond signal recovery in all optical gate operation using a type II tunneling bi-quantum well (TBQ) etalon. The type II TBQ consists of a series of GaAs wells, AlGaAs barriers, and AlAs layers. In this structure, photoexcited electrons in the GaAs wells escape by tunneling through the AlGaAs barriers toward X states in the AlAs layers. Therefore, the time for recovery from excitonic absorption bleaching in GaAs wells is controlled directly by the AlGaAs barrier thickness. The type II TBQ etalon with 1.7 nm barriers showed a fast signal recovery of 17 ps by carrier tunneling.