Resonant degenerate four-wave mixing in GaAs multiquantum well structures

Abstract
We have observed degenerate four‐wave mixing, on a picosecond timescale, at the lowest two‐dimensional exciton resonance line of GaAs‐Al0.25Ga0.75As layer structures, grown by molecular beam epitaxy. Mixing is observed at exciton densities as low as 109 cm−2 per layer and is strongly resonant at the heavy exciton line, where the diffraction efficiency reaches a maximum of 12% for a 2×10−7 J/cm2 pump pulse.