Non-Hermitian optics in a single nonlinear microcavity

Abstract

Optical microcavities are inherently non-Hermitian in nature, offering a fertile ground to test recent emerging development in non-Hermitian physics. Among them, representative examples include coherent perfect absorption (CPA)/critical coupling, electromagnetically induced transparency (EIT), parity-time symmetric coupled resonators, exceptional points (EP). In this talk, we shall discuss our group’s efforts in non-Hermitian optics in a single microcavity by extending an additional dimension such as frequency through internal nonlinear optical processes. Within a single whispering-gallery-mode type microcavity, we show nonlinearity can alter the total transmission of a CPA, examining such a critical coupling mechanism in the nonlinear regime. Similarly, we demonstrate a new mechanism of optically induced transparency in a micro-cavity by introducing a four-wave mixing gain to nonlinearly couple two separated resonances of the micro-cavity in an ambient environment.