Localized polariton states in a photonic crystal intercalated by a transition metal dichalcogenide monolayer

Beyond the extensively studied microcavity polaritons, which are coupled modes of semiconductor excitons and microcavity photons, nearly 2D semiconductors placed in a suitable environment can support spatially localized exciton–polariton modes. We demonstrate theoretically that two distinct types of such modes can exist in a photonic crystal with an embedded transition metal dichalcogenide (TMD) monolayer and derive an equation that determines their dispersion relations. The localized modes of two types occur in the zeroth- and first-order stop bands of the crystal and have substantially different properties. The latter type of localized modes, which appear inside the light cone, can be described as a result of coupling of the TMD exciton and an optical Tamm state of the TMD-intercalated photonic crystal. We suggest an experiment for detecting these modes and simulate it numerically.Y.V.B., N.M.R.P., and M.I.V. acknowledge support from the European Commission through the project “Graphene-Driven Revolutions in ICT and Beyond”- Core 3 (Ref. No. 881603) and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020. Authors also acknowledge FEDER and FCT for support through projects POCI-01-0145-FEDER-028114 and PTDC/FIS-MAC/28887/2017