Plexcitonic strong coupling: unique features, applications, and challenges

There have recently been remarkable achievements in turning light-matter interaction into strong-coupling quantum regime. In particular, room-temperature plexcitonic strong coupling in plasmon-exciton hybrid systems can bring promising benefits for fundamental and applied physics. Herein, we review theoretical insight and recent experimental achievements in plexcitonic strong coupling, and divide this review into two main parts. The first part briefly introduces the general field of strong coupling, including its origin and history, physical mechanisms and theoretical models, as well as recent advanced applications of strong coupling, such as quantum or biochemical devices enabled by optical strong coupling. The second part concentrates on plexcitonic strong coupling by introducing its unique features and new potentials (such as single-particle ultrastrong coupling, strong-coupling dynamics in femtosecond scale) and discusses the limitations and challenges of plexcitonic strong coupling. This will also be accompanied by potential solutions, such as microcavity-engineered plexcitonics, spectral hole burning effects and metamaterial-based strong coupling. Finally, we summarize and conclude this review, highlighting future research directions and promising applications.