Understanding the different exciton-plasmon coupling regimes in two-dimensional semiconductors coupled with plasmonic lattices: a combined experimental and unified equations of motion approach

TL;DR

This paper investigates exciton-plasmon interactions in 2D semiconductors coupled with plasmonic lattices, using a combined experimental approach and a unified equations of motion model to understand different coupling regimes.

Contribution

It introduces a comprehensive EOM-based model that unifies the description of weak, intermediate, and strong exciton-plasmon coupling in 2D materials with plasmonic structures.

Findings

Unified EOM model accurately describes dispersion and lineshapes.

Different coupling regimes are systematically characterized.

Design insights for 2D exciton-plasmonic devices are provided.

Abstract

We study exciton-plasmon coupling in two-dimensional semiconductors coupled with Ag plasmonic lattices via angle-resolved reflectance spectroscopy and by solving the equations of motion (EOMs) in a coupled oscillator model accounting for all the resonances of the system. Five resonances are considered in the EOM model: semiconductor A and B excitons, localized surface plasmon resonances (LSPRs) of plasmonic nanostructures and the lattice diffraction modes of the plasmonic array. We investigated the exciton-plasmon coupling in different 2D semiconductors and plasmonic lattice geometries, including monolayer MoS2 and WS2 coupled with Ag nanodisk and bowtie arrays, and examined the dispersion and lineshape evolution in the coupled systems via the EOM model with different exciton-plasmon coupling parameters. The EOM approach provides a unified description of the exciton-plasmon interaction in the weak, intermediate and strong coupling cases with correctly explaining the dispersion and lineshapes of the complex system. This study provides a much deeper understanding of light-matter interactions in multilevel systems in general and will be useful to instruct the design of novel two-dimensional exciton-plasmonic devices for a variety of optoelectronic applications with precisely tailored responses.