From weak to strong coupling of localized surface plasmons to guided modes in a luminescent slab

TL;DR

This paper explores how varying the thickness of a waveguide influences the transition from weak to strong coupling between localized surface plasmons and guided modes in a luminescent slab, revealing new ways to control nanoscale light emission.

Contribution

It demonstrates the tunable transition from weak to strong coupling in a nanoantenna-waveguide system and its impact on emission and radiation patterns, offering novel design strategies for nanoscale light sources.

Findings

Transition from weak to strong coupling observed experimentally.

Modification of radiation patterns without changing nanoantenna design.

Non-trivial relationship between extinction and emission dispersion diagrams.

Abstract

We investigate a periodic array of aluminum nanoantennas embedded in a light-emitting slab waveguide. By varying the waveguide thickness we demonstrate the transition from weak to strong coupling between localized surface plasmons in the nanoantennas and refractive index guided modes in the waveguide. We experimentally observe a non-trivial relationship between extinction and emission dispersion diagrams across the weak to strong coupling transition. These results have implications for a broad class of photonic structures where sources are embedded within coupled resonators. For nanoantenna arrays, strong vs. weak coupling leads to drastic modifications of radiation patterns without modifying the nanoantennas themselves, thereby representing an unprecedented design strategy for nanoscale light sources.