Spin-polarized lasing in a highly photoexcited semiconductor microcavity

TL;DR

This paper reports room-temperature, ultrafast spin-polarized lasing in a GaAs microcavity with quantum wells, driven by spin-dependent stimulated processes in a high-density electron-hole plasma, maintaining high circular polarization.

Contribution

It demonstrates the first room-temperature spin-polarized lasing in a highly excited semiconductor microcavity with ultrafast dynamics and persistent polarization.

Findings

Lasing occurs at room temperature with ~10 ps pulse duration.

Lasing remains highly circularly polarized despite elliptical excitation.

Lasing energy shifts with excitation density, indicating nonlinear effects.

Abstract

We demonstrate room-temperature spin-polarized ultrafast ($\sim$10 ps) lasing in a highly optically excited GaAs microcavity. This microcavity is embedded with InGaAs multiple quantum wells in which the spin relaxation time is less than 10 ps. The laser radiation remains highly circularly polarized even when excited by nonresonant elliptically polarized light. The lasing energy is not locked to the bare cavity resonance, and shifts $\sim$10 meV as a function of the photoexcited density. Such spin-polarized lasing is attributed to a spin-dependent stimulated process of correlated electron-hole pairs. These pairs are formed near the Fermi edge in a high-density electron-hole plasma coupled to the cavity light field.