Theory of terahertz/near-infrared optical mixing in quantum wells in strong magnetic fields

Recently, strong near-band-gap emission lines, or sidebands, were discovered in undoped GaAs quantum wells illuminated simultaneously by near-infrared and terahertz (THz) radiation in strong magnetic fields [J. Kono et at, Phys. Rev. Lett. 79, 1758 (1997) and references therein]. We have developed a perturbation theory for this phenomenon. Assuming that the THz radiation induces transitions between magnetoexciton levels, we modeled the sideband generation as a third-order optical process and obtained the susceptibility. Our theory successfully explains ail the observed features of the sidebands. Moreover, we have shown that the magnetic field dependence of the sideband intensities exhibits a rich spectrum of resonances that originate from intraexciton transitions, demonstrating the power and usefulness of sideband generation in relation to magnetoexcitan spectroscopy. [S0163-1829(98)08708-6].