Laser emission with excitonic gain in a ZnO planar microcavity

TL;DR

This paper demonstrates laser emission from a ZnO planar microcavity across a temperature range, revealing excitonic gain mechanisms and a transition from strong to weak coupling regimes.

Contribution

It provides the first observation of excitonic gain in a ZnO microcavity and details the temperature-dependent coupling regime transition.

Findings

Lasing observed from 80 K to 300 K

Gain-related transition occurs below 240 K

Transition from strong to weak coupling at laser threshold

Abstract

The lasing operation of a ZnO planar microcavity under optical pumping is demonstrated from T=80 K to 300 K. At the laser threshold, the cavity switches from the strong coupling to the weak coupling regime. A gain-related transition, which appears while still observing polariton branches and, thus, with stable excitons, is observed below 240K. This shows that exciton scattering processes, typical of II-VI semiconductors, are involved in the gain process.