Intersubband electroluminescent devices operating in the strong coupling regime

TL;DR

This paper investigates intersubband electroluminescent devices operating in the strong coupling regime, revealing distinct spectral features and demonstrating the impact of strong light-matter coupling on emission properties.

Contribution

It provides a detailed experimental and theoretical analysis of electroluminescence in strong coupling, including device characterization and spectral simulation.

Findings

Identification of two emission features linked to polariton states

Demonstration of electroluminescence at otherwise inaccessible energies

Validation of spectral models based on polariton density of states

Abstract

We present a detailed study of the electroluminescence of intersubband devices operating in the light-matter strong coupling regime. The devices have been characterized by performing angle resolved spectroscopy that shows two distinct light intensity spots in the momentum-energy phase diagram. These two features of the electroluminescence spectra are associated with photons emitted from the lower polariton branch and from the weak coupling of the intersubband transition with an excited cavity mode. The same electroluminescent active region has been processed into devices with and without the optical microcavity to illustrate the difference between a device operating in the strong and weak coupling regime. The spectra are very well simulated as the product of the polariton optical density of states, and a function describing the energy window in which the polariton states are populated. The voltage evolution of the spectra shows that the strong coupling regime allows the observation of the electroluminescence at energies otherwise inaccessible.