# Quantum-Electron Back Action on Hybridization of Radiative and Evanescent Field Modes

## TL;DR

This paper investigates how Dirac electrons in graphene influence the hybridization of radiative and evanescent fields, revealing a back action that enhances sensing capabilities and enables new optical phenomena like polariton condensation.

## Contribution

It introduces the concept of back action from graphene electrons on surface plasmon-polaritons, providing a new perspective and tools for manipulating light-matter interactions in nanostructures.

## Key findings

- Back action modifies incident SPP fields significantly.
- High sensitivity to local dielectric environments demonstrated.
- Resonant absorption peaks enable polariton condensation.

## Abstract

A back action from Dirac electrons in graphene on the hybridization of radiative and evanescent fields is found as an analogy to Newton's third law. Here, the back action appears as a localized polarization field which greatly modifies an incident surface-plasmon-polariton (SPP) field. This yields a high sensitivity to local dielectric environments and provides a scrutiny tool for molecules or proteins selectively bounded with carbons. A scattering matrix is shown with varied frequencies nearby the surface-plasmon (SP) resonance for the increase, decrease and even a full suppression of the polarization field, which enables accurate effective-medium theories to be constructed for Maxwell-equation finite-difference time-domain methods. Moreover, double peaks in the absorption spectra for hybrid SP and graphene-plasmon modes are significant only with a large conductor plasma frequency, but are overshadowed by a round SPP peak at a small plasma frequency as the graphene is placed close to conductor surface. These resonant absorptions facilitate the polariton-only excitations, leading to polariton condensation for a threshold-free laser.