Rydberg polaritons in ReS2 crystals

TL;DR

This paper demonstrates strong light-matter coupling in ReS2 crystals, revealing their potential as solid-state Rydberg-like systems with unique optical properties suitable for advanced photonic applications.

Contribution

It provides the first clear evidence of strong polariton interactions in ReS2 and clarifies the origin of key spectral features related to high refractive index and oscillator strength.

Findings

Strong coupling between cavity modes and excited states in ReS2

Identification of spectral features due to high refractive index and oscillator strength

Potential of ReS2 for optical device applications

Abstract

Rhenium disulfide (ReS2) belongs to group-VII transition metal dichalcogenide (TMDs) with attractive properties such as exceptionally high refractive index and significant oscillator strength, large in-plane birefringence, and good chemical stability. Unlike most other TMDs, the peculiar optical properties of ReS2 persist from bulk to the monolayer, making this material potentially suitable for applications in optical devices. In this work, we demonstrate with unprecedented clarity the strong coupling between cavity modes and excited states, which results in a strong polariton interaction, showing the interest of such materials as a solid-state counterpart of Rydberg atomic systems. Moreover, we definitively clarify the nature of important spectral features, shedding light on some controversial aspects or incomplete interpretations and demonstrating that their origin is due to the interesting combination of the very high refractive index and the large oscillator strength expressed by these TMDs.