Relaxation of coherent TO phonons is investigated in bulk GaAs and InP
using an infrared time-resolved coherent anti-Stokes Raman scattering
technique. Measurements were performed as a function of the crystal t
emperature in the range 10-300 K permitting determination of the domin
ant TO phonon relaxation channels. The experimental results an consist
ent with TO phonon decay into a TA and a LA phonon in GaAs while in In
P decay into two identical energy LA phonons dominates at low temperat
ures.