Tunable Open-Access Microcavities for Solid-State Quantum Photonics and Polaritonics

Optical microcavities are powerful platforms widely applied in quantum information and integrated photonic circuits, among which the open-access microcavity is a newly emerging cavity structure consisting of a micro-sized concave mirror and a planar mirror controlled individually by groups of nanopositioners, whilst light emitters can be grown or transferred at the antinode of the cavity optical modes. Compared with monolithic microcavities, the open-access microcavity enables the simultaneous realization of small mode volume, large-range tunability, flexible structural engineering, and easiness for integration with external emitters, exhibiting extensive applications in the fields of solid-state quantum photonics and polaritonics over the last decade. This review first introduces the basic theory and the construction methods of open-access microcavities, followed by the recent advances of their applications in exciton-polaritons, photon condensates, quantum light sources, and nanoparticle sensing.