Emulating exceptional-point encirclements using imperfect (leaky) photonic components

Abstract: Non-Hermitian systems have recently attracted significant attention in photonics. One of the hallmarks of these systems is the possibility of realizing asymmetric mode switching and omnipolarizer action through the dynamic encirclement of exceptional points (EP). Here, we offer a new perspective on the operating principle of these devices, and we theoretically and experimentally show that asymmetric mode switching and omni-polarizer action can be easily realized with the same performance and limitations, using simple configurations that emulate the physics involved in encircling EPs without the complexity of actual encirclement schemes. The proposed concept of 'encirclement emulators' and our theoretical and experimental results may allow a better assessment of the limitations, practical potential, and applications of EP encirclements in non-Hermitian photonics.