Nonreciprocal light transmission in gain-loss modulated Micro ring resonators

We propose a new type of add-drop Micro ring resonator that is made up of gain and loss materials. In all-dielectric linear systems, light transmission is reciprocal: A symmetric transmission spectrum is observed when an incident source is pumped from one side and output power detected in the other side or vice versa. On the other hand, Parity-time (PT) symmetric optical systems that consist of balanced gain-loss modulation possess unique characteristics such as unidirectional beam propagation, asymmetric light transmission and nonreciprocal chirality. In this study, we proved numerically that PT symmetric optical resonator designs can be achieved by properly arranging the gain-loss modulation so that different resonant modes can be promoted depending on the direction of source incidence.