Nanophotonics of microcavity exciton-polaritons

The past 30 years have witnessed remarkable developments of microcavity exciton-polaritons, which have made a great impact on photonics and optoelectronics from fundamental physics to device applications. New materials and optical structures have been developed for novel polariton lasers for the sake of room temperature operation, flexible mode engineering, and high power efficiency. More powerful spectroscopic techniques have also promoted the understanding of polariton dynamics, coherence, nonlinearity, and topology. In this review, we start with a brief introduction to the picture of polaritons, and various polariton systems based on different microcavity structures and semiconductor materials. Then, we present several important spectroscopic techniques and numerical tools for characterizing polaritons experimentally and theoretically. Next, we address the macroscopic quantum phenomena observed in the polariton systems and review the physics and applications of polariton nonlinearity. Moreover, we highlight the new emerging fields of topological and non-Hermitian polaritons. In the end, we conclude with the future perspectives of microcavity exciton-polaritons.