Imaging exciton-polariton transport in MoSe2 waveguides

TL;DR

This study demonstrates the imaging and control of exciton-polariton waveguides in MoSe2, revealing their propagation characteristics and dispersion properties, which are promising for future nanophotonic applications.

Contribution

It provides the first nano-optical imaging of waveguide exciton-polaritons in MoSe2, showing tunable wavelengths and long propagation lengths at room temperature.

Findings

Propagation length exceeds 12 μm

Polariton wavelength tunable from 600 nm to 300 nm

Observation of mode back-bending dispersion near exciton resonance

Abstract

The exciton polariton (EP), a half-light and half-matter quasiparticle, is potentially an important element for future photonic and quantum technologies. It provides both strong light-matter interactions and long-distance propagation that is necessary for applications associated with energy or information transfer. Recently, strongly-coupled cavity EPs at room temperature have been demonstrated in van der Waals (vdW) materials due to their strongly-bound excitons. Here we report a nano-optical imaging study of waveguide EPs in MoSe2, a prototypical vdW semiconductor. The measured propagation length of the EPs is sensitive to the excitation photon energy and reaches over 12 {\mu}m. The polariton wavelength can be conveniently altered from 600 nm down to 300 nm by controlling the waveguide thickness. Furthermore, we found an intriguing mode back-bending dispersion close to the exciton resonance. The observed EPs in vdW semiconductors could be useful in future nanophotonic circuits operating in the near-infrared to visible spectral regions.