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 al., 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 all 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 magnetoexciton spectroscopy.