Ultrathin WS2-on-Glass Photonic Crystal for Self-Resonant Exciton-Polaritonics

Room temperature stable excitons in layered two-dimensional (2D) transition metal dichalcogenides (TMDs) offer a unique route for engineering light and matter interactions. Due to the strong optical dispersion near the excitonic transitions, a high refractive index arises in these ultrathin semiconductors.([1,2]) Utilizing this behavior, strongly confined Fano type optical resonances in an ultrathin (i.e., approximate to 12 nm) tungsten disulfide (WS2) photonic crystal (PhC) directly fabricated on a TMD-on-glass platform are reported. In this approach, Fano-type WS2 photonic resonances strongly couple to the WS2 excitonic dispersion engender self-resonant exciton-polaritons with an out-of-plane optical confinement exceeding that provided by surface plasmon polaritons in the visible. The large spatial light-matter overlap endowed by this unique monolithic self-coupling scheme is utilized for steering of enhanced 2D WSe2 excitonic photoluminescence in a truly TMD integrated system. It is envisioned that the strong light matter interaction on the TMD-on-glass platform will unfold the prospects of ultrathin exciton-polaritonic resonators.