Engineering strong coupling in ultra-compact photonic crystal/2D material platforms

TL;DR

This paper explores how to engineer and control strong light-matter coupling in ultra-compact photonic crystal and 2D material platforms, enabling tunable on-chip optoelectronic devices.

Contribution

It demonstrates how photonic crystal geometry and spatial patterning of 2D materials can tailor exciton-polariton interactions and spectra.

Findings

PhC polaritons can be modeled as dark waveguide modes brightened by periodicity.

Spatial patterning of TMD monolayers reveals simultaneous weak and strong coupling regimes.

Fundamental insights into strong coupling in structured photonic environments are provided.

Abstract

Sub-wavelength thick photonic crystal (PhC) slabs coupled to 2D excitonic materials, such as transition metal dichalcogenides (TMDs), are a promising platform for highly tunable, room-temperature, on-chip optoelectronic devices. Unlike conventional Fabry-Perot microcavities, these compact open cavities exhibit non-trivial electric field profiles, leading to spatially distinct regions of weak and strong coupling with excitons within the PhC unit cell. Using coupled mode theory and rigorous solutions to Maxwell's equations, we investigate how the PhC geometry can be used to control these coexisting exciton/polariton contributions and tailor the resulting optical spectra. For large filling factors, i.e., small air gaps, we show that PhC polaritons can be modeled as dark waveguide modes brightened via the periodicity of the PhC slab. Furthermore, by spatially patterning the TMD monolayer based on the local field intensity, we reveal the simultaneous presence of excitons in both the weak and strong coupling regimes. Overall, this work provides fundamental insights into the strong light-matter coupling regime in structured photonic environments, offering a pathway to design and optimize metal-free, ultra-compact polaritonic devices.