Raman Scattering from Nonequilibrium LO Phonons with Picosecond Resolution

Abstract

A novel technique is described for time-resolved Raman scattering for studying the dynamics of nonequilibrium excitations on a picosecond time scale. The generation and the decay of nonthermal LO phonons in GaAs is measured, and ${\ensuremath{\tau}}^{\ensuremath{'}}=7\ifmmode\pm\else\textpm\fi{}1$ ps is obtained for the relaxation time of the phonon population at 77 K.