Strong-field terahertz optical sideband generation for wavelength conversion in asymmetric double quantum wells

Terahertz (THz) optical sideband generation in asymmetric double quantum wells in strong THz fields is studied theoretically. Both monotonic THz-power dependence and saturation of the first-order sideband intensity can occur, depending on the near infrared (NIR) and THz photon energies. In both respects the calculated sideband intensity behavior agrees with experimental findings (Appl. Phys. Lett. 75, 2728 (1999); Phys. Rev. B 70, 115312 (2004)]. The nonmonotonic THz-power dependence and saturation of the sideband intensity are due to the excitonic Stark splitting. While the sideband saturation imposes limitations on the wavelength conversion efficiency, the simultaneous broadening of sideband resonances benefits wavelength conversion by increasing the number of NIR frequencies available for wavelength conversion. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3273392]