Active Control of Surface Plasmon–Emitter Strong Coupling

Strong coupling between quantum emitters and surface plasmon polariton modes in metal nanostructures has been extensively studied in recent years. A natural direction of research and a prerequisite for many applications is the possibility of external, in situ manipulation of the strength of the coupling. We review research on active control of surface plasmon–emitter strong coupling phenomena. Active control has been demonstrated for a variety of systems, such as metal nanohole arrays, nanoparticles, rods and dimers, combined with photochromic molecules, J-aggregates, and monolayers of MoS2, WS2, and WSe2. We discuss work on optical switching realized by changing photochromic molecules by UV and visible light between forms that couple strongly or weakly with the electromagnetic field mode of the plasmonic nanostructure. Other forms of optical control such as use of polarization and phase are briefly covered. We review research on electrical, thermal, and chemical active control of light–matter coupling in plasmonic systems.