Optical absorption and nonlinear mixing of near-infrared and terahertz wave in quantum wells

Linear optical absorption and terahertz (THz) sideband generation in quantum wells in the presence of a strong growth-direction oriented THz electric field is investigated. It is shown that the THz field can couple more than two levels simultaneously. The absorption spectra show a rich variety of behavior, including THz replicas of the 2 p exciton and THz sideband of the Is exciton. The THz electric field results in multiple optical absorption peaks due to resonant coupling between the valence subbands and produces splittings in the generated sidebands.