Nonlinear optical nonreciprocity in a surface plasmon–exciton coupled asymmetric cavity system

Optical nonreciprocity and nonreciprocal devices have attracted great research interest in recent years, due to their important applications in optical communication, information processing, etc. In this work, we investigate optical nonreciprocity in the quantum dot–metal nanoparticle (QD-MNP) hybrid system inside an asymmetric cavity. Due to the optical nonlinear effect, the input–output relationship of the cavity shows a bistable S -shaped curve, which can be employed to achieve optical nonreciprocity in the asymmetric cavity system. Nonlinear interaction between photons and QD excitons can be strengthened by using the surface plasmon effect in the QD-MNP nanostructures, providing the possibility of realizing better performance of optical nonreciprocity compared with the single QDs. Not only the light transmittance is enhanced in one direction while further suppressed in the reverse direction, but also the intensity threshold for generating optical nonreciprocity is also reduced in the hybrid surface plasmon–exciton cavity system. Our work may provide references for novel design and experimental realization of nonlinearity-based optical nonreciprocal devices. Graphical Abstract Surface plasmon can significantly enhance the nonlinear effect in the MNP-QDs hybrid system. In order to improve performance of the optical nonreciprocity, we introduce the hybrid system in an asymmetric F-P cavity and use the bistable input–output property to achieve optical nonreciprocity. Compared with single QDs, isolation performance of the hybrid surface plasmon cavity can be obviously enhanced.