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

TL;DR

This study uses femtosecond laser pulses to control and understand the delayed formation of LO phonon-plasmon coupled modes in n- and p-type GaAs, revealing the importance of mode lifetime and pulse interference.

Contribution

It introduces a phenomenological model that accounts for the delayed formation of coherent LOPC modes, highlighting the role of mode lifetime and pulse interference in mode manipulation.

Findings

Distinct responses observed in p- and n-type GaAs with interpulse separation.

The mode lifetime significantly influences the coherent LOPC mode formation.

Interference of successive LO phonons affects mode manipulation.

Abstract

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