Bifurcated overtones of one-way localized Fabry-Pérot resonances in parity-time symmetric optical lattices

摘要

Since the first observation of parity-time (PT) symmetry in optics,varied interesting phenomena have been discovered in both theories and experiments,such as PT phase transition and unidirectional invisibility,which turns PT-symmetric optics into a hotspot in research.Here,we report on the one-way localized Fabry-Pérot (FP) resonance,where a welldesigned PT optical resonator may operate at exceptional points with bidirectional transparency but unidirectional field localization.Overtones of such one-way localized FP resonance can be classified into a blue shifted branch and a red shifted branch.Therefore,the fundamental resonant frequency is not the lowest one.We find that the spatial field distributions of the overtones at the same absolute order are almost the same,even though their frequencies are quite different.