Ultrafast all-optical modulation of interband-light pulses by ultrashort intersubband light pulses in semiconductor quantum wells

Abstract

We analyze the optical modulation of an interband resonant light pulse by intersubband resonant light pulses in a three-level quantum well system. The origin of the third order self-saturation optical nonlinearity resulting in the modification of the interband light absorption is assumed to lie in the carrier density modulation induced by the interband and intersubband transitions. The optical nonlinearity can be optimized to achieve the maximum modulation by applying control light pulses shorter than the intersubband energy relaxation time but longer than the intersubband phase relaxation time. We have also experimentally investigated the material system suitable for optical communication regime and have observed that the In0.53Ga0.47As/AlAs0.56Sb0.44 quantum well lattice matched to InP yielding an intersubband transition as short as 1.4 μm is the most suitable system for the proposed modulation scheme.