Enhanced optical/THz frequency mixing in a biased quantum well

Strong enhancement of the optical emission at THz sidebands from a THz-field driven quantum well in the presence of a dc bias is predicted. The process of the THz/optical mixing is formulated as the interaction of the incident light with THz-dressed excitons. This allows one to find nonperturbative analytic expressions for the conversion efficiency of the fundamental to the THz sidebands. A maximum efficiency of a few percent is predicted for a single GaAs quantum well, and ways for its further enhancement are discussed.