Intersubband transitions at 1.3 and 1.55 /spl mu/m in a novel coupled InGaAs-AlAsSb double-quantum-well structure

Abstract
We report the first observation of intersubband absorption at 1.3 /spl mu/m in a coupled InGaAs-AlAsSb double-quantum-well structure lattice matched to InP substrate. The novel structure exhibits intersubband transitions concurrently at 1.3 and 1.55 /spl mu/m due to the strong coupling of the intersubband states of the adjacent wells. A transient analysis of optical response in the multilevel conduction subband states for the designed structure indicates ultrafast optical switching behavior with a subpicosecond response.