Characterization of the optical properties of gallium arsenide as a function of pump intensity using picosecond ultrasonics

Abstract

We report the observation of coherent acoustic phonon oscillations in GaSb(20 nm)/GaAs near the band gap of GaAs at room temperature. A photogenerated longitudinal acoustic phonon wave travels from the top surface of GaSb and into the GaAs substrate and gives rise to oscillations which provide useful information on the properties of GaAs as a function of depth and time. Using a time-resolved pump-probe technique, we investigate how the characteristics of the phonon oscillations change with intensity in the low-intensity regime near the band gap of GaAS and propose our technique as a method to quantify the optical properties of GaAs at room temperature.