Emitter-Vacuum coupling through a leaky nanostructure and the role of dynamics in density of optical states

TL;DR

This paper challenges traditional views on optical states in emitter-vacuum systems, revealing non-local effects and quantum phenomena that impact nanostructure-based sensing techniques like SERS.

Contribution

It introduces a non-local fluctuation-dissipation model explaining deviations in optical behavior near absorbing nanostructures, highlighting quantum effects in optical state partitioning.

Findings

Experimental divergence from classical theory in nanoparticle-emitter interactions

Identification of non-local behavior in small metal nanoparticles

Implications for the viability of SERS and similar sensing techniques

Abstract

We show a break down of the conventional partition of optical states into its radiative and non-radiative parts. Large divergence of experimental observations from current theory in the case of emitters interacting with fully absorbing plasmonic nanoparticles only a few nanometers in dimensions, are now evident. A model of fluctuation-dissipation demands non-local behavior from limiting small metal nanoparticles and proximal metal surfaces. We point that widely used techniques to enhance optical sensing such as surface-enhanced-Raman-spectroscopy (SERS), may not have been viable but for this effect. Qualitatively, this quantum effect seems to present itself only when the classical probability of scattering of an emitted photon by a near-by absorbing nanostructure approaches zero. Hence, though different in origin and scale, this has an interesting analogy with quantum effects resulting in Hawking radiation near a black-hole.