Picosecond degenerate four-wave mixing through orientation and concentration gratings in GaAs

Abstract

We report the observation of degenerate four-wave mixing in GaAs above the band gap, using tunable picosecond pulses in the 1.53–1.61-eV region. A very fast contribution due to orientational gratings of electron-hole pairs is isolated with orthogonally polarized beams. This is observed for incident intensities down to 5 MW/cm2, i.e., two orders of magnitude lower than recently reported for germanium. Even at this relatively low power density, higher order effects are important, as evidenced by the power dependence of the conversion efficiency.