Time-resolved observation of coherent phonons by the Franz-Keldysh effect

Abstract

We report on the time-resolved observation of coherent optical phonons in GaAs by the Franz-Keldysh effect. This effect leads to a modulation of the optical interband transitions with a nonlinear dependence on the macroscopic electric field associated with the coherent phonons. We find that the nonlinear electro-optic effect forms a far more efficient detection mechanism for coherent phonons than the linear electro-optic effect near the band gap. © 1996 The American Physical Society.