Ultralow Threshold Polariton Condensate in a Monolayer Semiconductor Microcavity at Room Temperature

TL;DR

This paper reports the first observation of exciton polariton condensation at room temperature in a monolayer TMD microcavity, demonstrating ultralow threshold lasing and potential for valleytronic devices.

Contribution

It demonstrates room-temperature polariton condensation and lasing in a TMD microcavity, a significant advancement for valleytronics and polaritonic device development.

Findings

Ultralow threshold polariton lasing observed at room temperature

Macroscopic ground state occupation with nonlinear emission increase

Spatial coherence and detuning-controlled threshold achieved

Abstract

Atomically thin transition metal dichalcogenides possess valley dependent functionalities that are usually available only at crogenic temperatures, constrained by various valley depolarization scatterings. The formation of exciton polaritons by coherently superimposing excitons and microcavity photons potentially harnesses the valley polarized polariton polariton interactions for novel valleytronics devices. Robust EPs have been demonstrated at room temperature in TMDs microcavity, however, the coherent polariton lasing and condensation remain elusive. Herein, we demonstrate for the first time the realization of EP condensation in a TMD microcavity at room temperature. The continuous wave pumped EP condensation and lasing with ultralow thresholdsis evidenced by the macroscopic occupation of the ground state, that undergoes a nonlinear increase of the emission and a continuous blueshift, a build up of spatial coherence, and a detuning-controlled threshold. Our work presents a critically important step towards exploiting nonlinear polariton polariton interactions and polaritonic devices with valley functionality at room temperature.