Enhancement of the spontaneous emission in subwavelength quasi-two-dimensional waveguides and resonators

TL;DR

This paper develops a quantum-electrodynamic framework to analyze and enhance spontaneous emission from 2D emitters in subwavelength waveguides and cavities, revealing potential emission enhancements of over 100 times.

Contribution

It introduces a general Heisenberg-Langevin approach that accounts for dissipation and fluctuations without specific reservoir models, applicable to nonequilibrium systems and simple geometries.

Findings

Spontaneous emission can be enhanced by a factor of 100 or more.

The approach is applicable to nonequilibrium and pumped electron systems.

Analytic results are derived for strip line and rectangular cavity geometries.

Abstract

We consider a quantum-electrodynamic problem of the spontaneous emission from a two-dimensional (2D) emitter, such as a quantum well or a 2D semiconductor, placed in a quasi-2D waveguide or cavity with subwavelength confinement in one direction. We apply the Heisenberg-Langevin approach which includes dissipation and fluctuations in the electron ensemble and in the electromagnetic field of a cavity on equal footing. The Langevin noise operators that we introduce do not depend on any particular model of dissipative reservoir and can be applied to any dissipation mechanism. Moreover, our approach is applicable to nonequilibrium electron systems, e.g. in the presence of pumping, beyond the applicability of the standard fluctuation-dissipation theorem. We derive analytic results for simple but practically important geometries: strip lines and rectangular cavities. Our results show that a significant enhancement of the spontaneous emission, by a factor of order 100 or higher, is possible for quantum wells and other 2D emitters in a subwavelength cavity.