Direct Observation of Self‐Hybridized Exciton‐Polaritons and Their Valley Polarizations in a Bare WS 2 Layer

作者：Dong‐Jin Shin, HyunHee Cho, Junghyun Sung, Su‐Hyun Gong · 发表于：Advanced Materials · 年份：2022 · DOI：10.1002/adma.202207735 · 被引用次数：16 · 研究领域：Strong Light-Matter Interactions、Plasmonic and Surface Plasmon Research、Perovskite Materials and Applications

Abstract The strong excitonic properties of transition metal dichalcogenides (TMD) have led to the successful demonstration of exciton‐polaritons (EPs) in various optical cavity structures. Recently, self‐hybridized EPs have been discovered in a bare TMD layer, but experimental investigation is still lacking because of their nonradiative nature. Herein, the direct observation of self‐hybridized EPs in a bare multilayer WS 2 via the evanescent field coupling technique is reported. Because of the thickness‐dependent Rabi splitting energy, the dispersion curves of the EPs change sensitively with sample thickness. Moreover, continuous tuning of EP dispersion curves is demonstrated by controlling the excitation laser power. Lastly, it is observed that guided EPs retain valley polarization up to 0.2 at room temperature, representing a valley‐preserved strong coupling regime. It is believed that the high tunability and valley polarization properties of the guided EPs in bare TMD layers can facilitate new nanophotonic and valleytronic applications.