Ultrathin WS_2 Polariton Waveguide for Efficient Light Guiding

摘要

Light confinement to sub-wavelength scales is actively studied fornanophotonic applications because it gives rise to intriguing opticalproperties with enhanced light-matter interaction. Herein, an ultrathinexciton–polariton waveguide based on a WS_2 multilayer is proposed forsub-wavelength light guiding. A WS_2 waveguide supports guidedexciton–polariton modes even with a few tens of nanometers of thickness. Itis theoretically confirmed that the WS_2 waveguide has significantly lowerpropagation loss than a plasmonic mode, although its thickness may besimilar to that of a plasmonic waveguide. By injecting white light into afabricated WS_2 waveguide, light guiding is experimentally demonstratedthrough a 20 nm thick WS_2 waveguide. Notably, this study integrated the WS_2waveguide with a WSe2 monolayer to demonstrate the coupling of monolayeremission to the polariton waveguide. The results suggest that WS_2multilayers provide a novel material platform with potential for nanophotonicapplications, including ultrathin optical integrated circuits.