Up-converted photoluminescence induced by radiative coupling between excitons

TL;DR

This paper introduces a novel photoluminescence mechanism in semiconductor thin films, where nonlocal exciton-light interactions lead to highly efficient up-converted emission without the need for cavities or antennas.

Contribution

It develops a new theoretical framework extending input-output theory to reveal unconventional exciton-light coupling effects in thin films.

Findings

Enhanced exciton-light coupling beyond long-wavelength approximation

Highly efficient up-converted photoluminescence achievable with weak pumping

No need for auxiliary photonic structures

Abstract

We propose an unconventional scheme of photoluminescence in a semiconductor thin film, where the nonlocal correlation between an excitonic wave and a light wave prominently enhances the exciton-light coupling beyond the long-wavelength approximation (the so-called excitonic superradiance regime). On the basis of the developed method extending input-output theory, we elucidate atypical photoluminescence effects due to the strong wave-wave correlation. In particular, the up-converted photoluminescence based on the coherent superposition of excitons is found to be highly efficient, i.e., it can be realized by weak pumping without auxiliary systems such as cavities or photonic antennas.