Coherent detection of THz-induced sideband emission from excitons in the nonperturbative regime

Nonlinear interaction of terahertz (THz) waves with excitons induces interesting optical effects such as Rabi splitting and high-order sideband generation. Here, we investigated the coherent properties of the THz-induced sideband emissions from GaAs/AlGaAs multi-quantum-wells, and determined the optical susceptibility of the THz dressed exciton in the nonperturbative regime. The strong dependences of both amplitude and phase of the second-order sideband emission on the THz electric field strength imply that the field ionization of the 1s exciton modifies the THz-dressed exciton\u27s energy spectrum