Time resolved excitonic coherent polarization dynamics in GaAs multiple quantum wells

TL;DR

This study uses femtosecond time-resolved pump-probe reflectivity to explore excitonic polarization dynamics in GaAs quantum wells, revealing interference effects between linear and nonlinear excitonic polarizations.

Contribution

It introduces the consideration of interference between linear and nonlinear excitonic polarization in pump-probe experiments, which was previously overlooked.

Findings

Interference effects significantly influence the temporal evolution of excitonic polarization.

Both positive and negative pump-probe delays show measurable modulation.

The results improve understanding of excitonic coherence in quantum wells.

Abstract

We investigate pump induced modulation in the temporal evolution of the excitonic coherent polarization generated by a probe pulse in GaAs multiple quantum wells. For this, we perform fs time resolved pump-probe reflectivity measurements using frequency upconversion at both positive and negative pump-probe delays. A contribution arising from interference of excitonic linear and nonlinear polarization, which is usually not considered in describing pump-probe experiments, is required to understand the results.