Voltage-controlled wavelength conversion by terahertz electro-optic modulation in double quantum wells

An undoped double quantum well (DQW) was driven with a terahertz (THz) electric field of frequency omega(THz) polarized in the growth direction, while simultaneously illuminated with a near-infrared (NIR) laser at frequency omega(NIR). The intensity of NIR upconverted sidebands omega(sideband)=omega(NIR)+omega(THz) was maximized when a dc voltage applied in the growth direction tuned the excitonic states into resonance with both the THz and NIR fields. There was no detectable upconversion far from resonance. The results demonstrate the possibility of using gated DQW devices for all-optical wavelength shifting between optical communication channels separated by up to a few THz. (C) 2002 American Institute of Physics.