Observation of Acoustically Induced Phase-Matched Optical Harmonic Generation in GaAs

Abstract
Radiation near 5.3 μm arising from the collinear phase-matched mixing of a 10.6-μm Q-switched laser beam and a pulsed ultrasonic shear wave has been observed in GaAs. Phase matching occurs when the crystal momentum of the acoustic phonon is adjusted to equal the familiar momentum mismatch observed in conventional second-harmonic generation in cubic GaAs. Three components of the susceptibility governing the four-wave interaction process were measured.