Delayed formation of coherent LO phonon-plasmon coupled modes in n-type and p-type GaAs measured using a femtosecond coherent control technique

摘要

Coherent control experiments using a pair of collinear femtosecond laserpulses have been carried out to manipulate longitudinal optical (LO)phonon-plasmon coupled (LOPC) modes in both p- and n-type GaAs. By tuning theinterpulse separation, remarkably distinct responses have been observed in thetwo samples. To understand the results obtained a phenomenological model takingthe delayed formation of coherent LOPC modes into account is proposed. Themodel suggests that the lifetime of coherent LOPC modes plays a key role andthe interference of the coherent LO phonons excited successively by two pumppulses strongly affects the manipulation of coherent LOPC modes.