THEORY OF TERAHERTZ NEAR-INFRARED OPTICAL MIXING IN QUANTUM-WELLS IN STRONG MAGNETIC-FIELDS/

Recently, strong near-band-gap emission lines, or sidebands, were disc overed in undoped GaAs quantum wells illuminated simultaneously by nea r-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 lev els, we modeled the sideband generation as a third-order optical proce ss and obtained the susceptibility. Our theory successfully explains a il the observed features of the sidebands. Moreover, we have shown tha t the magnetic field dependence of the sideband intensities exhibits a rich spectrum of resonances that originate from intraexciton transiti ons, demonstrating the power and usefulness of sideband generation in relation to magnetoexcitan spectroscopy. [S0163-1829(98)08708-6].