Nonlinear Optical Radiation of a Lithium Niobate Microcavity

The nonlinear coupling between on-chip confined optical modes and free-space continuum is investigated. radiation of second-harmonic wave due to the pump fields in integrated lithium niobate microcavities experimentally observed. mechanism (NOR) further verified by demonstrating reversal process NOR, i.e., difference frequency generation a input an field. revealed NOR universal for all dielectric photonic devices, which indicates unavoidable extra energy leakage channels micro- nanostructures, also enables alternative approach spatial engineering light sources. For example, benefited from phase-matching-free nature atomic gas sensor absorption spectroscopy Rb atoms built.