Mutual transparency of coherent laser beams through a terahertz-field-driven quantum well

Quantum-well excitons dressed by a terahertz field have multiple optical resonances. An optical beam tuned to any of the resonant frequencies excites the dressed-exciton state; therefore the optical beam experiences attenuation upon its transmission. For two coherent optical beams tuned to two different resonant frequencies, however, one can judiciously choose the amplitudes and phases in such a way that the beams do not produce any excitation, and thus they experience no attenuation, even though each of beams would be strongly attenuated in the absence of the other. This two-color scheme also suggests coherent control of dressed excitons by a pair of phase-locked pulses with different carrier frequencies and nonoverlapping spectra. © 2002 Optical Society of America OCIS codes: 190.5970, 230.2090.