Transient dual-energy lasing in a semiconductor microcavity

TL;DR

This paper reports the observation of sequential, polarized lasing at two distinct energies in a semiconductor microcavity at room temperature, revealing transient spin dynamics and energy separation in the lasing states.

Contribution

It demonstrates for the first time the occurrence of transient dual-energy lasing with distinct polarization properties in a semiconductor microcavity at room temperature.

Findings

Sequential lasing at two energies separated by over 5 meV.

The high-energy state is circularly polarized and short-lived (~10 ps).

The low-energy state follows, with reduced polarization and longer duration (20-50 ps).

Abstract

We demonstrate sequential lasing at two well-separated energies in a highly photoexcited planar microcavity at room temperature. Two spatially overlapped lasing states with distinct polarization properties appear at energies more than 5 meV apart. Under a circularly polarized nonresonant 2 ps pulse excitation, a sub-10-ps transient circularly polarized high-energy (HE) state emerges within 10 ps after the pulse excitation. This HE state is followed by a pulsed state that lasts for 20--50 ps at a low energy (LE) state. The HE state is highly circularly polarized as a result of a spin-preserving stimulated process, while the LE state shows a significantly reduced circular polarization because of a diminishing spin imbalance.