Nonlinear Terahertz Electroluminescence from Dirac Landau Polaritons

TL;DR

This paper demonstrates strong coupling between Dirac fermions in HgTe quantum wells and optical cavity modes, leading to nonlinear terahertz electroluminescence and potential for tunable THz polariton lasers.

Contribution

It reports the first observation of Dirac Landau polaritons with nonlinear electroluminescence under electrical injection, indicating possible polariton condensation and lasing.

Findings

Observation of Dirac Landau polaritons via magnetoreflectivity.

Efficient nonlinear electroluminescence with spectral narrowing.

Evidence suggesting stimulated polariton emission near upper anticrossing.

Abstract

We report Dirac Landau polaritons observed by terahertz (THz) magnetoreflectivity spectroscopy, demonstrating strong coupling between cyclotron transitions of two-dimensional (2D) Dirac fermions in HgTe quantum wells and optical cavity modes. Under pulsed electrical injection we observe efficient nonlinear electroluminescence, with a strongly out-of-equilibrium polariton distribution dominated by emission from the upper polariton branches. Model analysis of the bias-dependent emission intensity and spectral narrowing indicates a polariton occupancy per mode approaching unity, with a possible contribution from stimulated polariton emission in the spectral region of the upper anticrossing. These results open prospects toward Dirac Landau polariton condensates and low-threshold, tunable THz polariton lasers based on cyclotron emission.