Abstract

Femtosecond time resolved coherent phonon oscillations are observed for the first time through impulsive stimulated Raman scattering (ISRS)/1/ in semiconductor Ill-V-compounds. Individual cycles of the phonon oscillations as well as the vibrational dephasing are demonstrated via a modulation of the time resolved reflectivity signatures through the electro-optic effect. The observed linear behaviour of oscillation amplitude on pump intensity confirms the excitation of coherent longitudinal polar optic phonons with a single femtosecond pulse via ISRS in GaAs, InP and AIGaAs. The macroscopic electric field associated with the lattice vibrations is measured via the electro-optic effect. This is confirmed through the distinct variation of reflectivity signal modulation versus relative orientation of probe beam polarization and crystal orientation in our pump/probe experiments.

© 1990 Optical Society of America