Femtosecond depolarization of photoluminescence from InAs: Comparison with Cu and monolayer graphene

We investigated the time-resolved photoluminescence (PL) of InAs, Cu, and monolayer graphene excited by linearly polarized femtosecond pulses. PL depolarization occurred in the femtosecond regime. The establishment of the isotropic momentum distribution of electrons is discussed based on the electron-electron and electron -phonon scattering. This study demonstrates the impact of a steep dispersion relation in the electron band structure on the electron-optical phonon scattering causing the ultrafast depolarization of PL.