Miniaturized optics from structured nanoscale cavities

Miniaturized and rationally assembled nanostructures exhibit extraordinarily distinct physical properties beyond their individual units. This review will focus on structured small-scale optical cavities, especially on plasmonic nanoparticle lattices that show unique electromagnetic near fields from collective optical coupling. By harnessing different material systems and structural designs, various light-matter interactions can be engineered, such as nanoscale lasing, nonlinear optics, and exciton-polariton coupling. Key device performance of nanoscale lasers will be discussed, including low power threshold, output tunability, and electrical pump. This review will also cover emerging applications of nanoscale optical cavities in quantum engineering. Structured nanoscale cavities can serve as a scalable platform for integrated photonic circuits and hybrid quantum photonic systems.