Self-induced transparency in a perfectly absorbing chiral second-harmonic generator

Abstract Transparency and perfect absorption are two contradictory terms; a absorber never permits waves to transmit through. However, this statement only remains true in the linear regime, where nonlinearity has been omitted physical system like is not affected by incoming waves. Here we experimentally demonstrate an intriguing self-induced transparency effect perfectly absorbing optical microcavity, which absorbs any at low power level, but allows portion of be transmitted higher due nonlinear coupling between fundamental its second harmonic modes. Moreover, asymmetric scattering nature microcavity enables chiral unidirectional reflection one input ports, leads coherent control states through phase varying. More importantly, such behaviors also empower emission second-harmonic generation with high distinct ratio state. These results pave way for controllable wide range fields optics, microwaves, acoustics, mechanics, matter