Non-Hermitian Optical Tunable System Based on Lithium Niobate Coupling Resonator

Recently, an exceptional point (EP) was constructed in a coupled double-ring resonator. Generally, such non-Hermitian optical systems are realized via material selection and a spatially precise layout. However, because of material limitations, some system parameters cannot be changed after the waveguide is fabricated. In this study, We demonstrate a lithium niobate-based tunable system for controlling system dispersion and loss, the resonator structure made of lithium niobate is theoretically and numerically investigated and analyzed. Lithium niobate is chosen because it exhibits good electro-optic properties. Furthermore, the real part of the potential energy term of the non-Hermitian system is regulated using external electric field. Consequently, a frequency shift of up to 149 GHz is observed in the double characteristic peak of the transmission spectrum with a contrast of up to 0.43. In addition, a gain-influenced EP is observed in a coupled dual-ring resonator system by introducing gain material. It has potential application in future optical fiber communication, optical quantum computing, and environmental sensing.