An engineered planar plasmonic reflector for polaritonic mode confinement

TL;DR

This paper introduces a plasmonic reflector design that confines polaritonic modes by creating an energy stopband, significantly enhancing light-matter coupling in deep subwavelength structures.

Contribution

The work presents a novel engineered planar plasmonic reflector that restores polaritonic resonances by confining plasmons, overcoming energy leakage issues in deep subwavelength resonators.

Findings

Achieved a normalized light-matter coupling ratio of 0.35

Demonstrated confinement in a gap of λ/2400

Restored polaritonic resonances in subwavelength structures

Abstract

It was recently demonstrated that, in deep subwavelength gap resonators coupled to two-dimensional electron gases, coupling to propagating plasmons can lead to energy leakage and prevent the formation of polaritonic resonances. This process, akin to Landau damping, limits the achievable field confinement and thus the value of light-matter coupling strength. In this work, we show how plasmonic subwavelength reflectors can be used to create an artificial energy stopband in the plasmon dispersion, confining them and enabling the recovery of the polaritonic resonances. Using this approach we demonstrate a normalized light-matter coupling ratio of {\Omega}/{\omega} = 0.35 employing a single quantum well with a gap size of {\lambda}/2400 in vacuum.