Dynamic Control of Non‐Hermitian On‐Site Potential in the Lithium Niobate Microresonator

Abstract Synthetic dimension, an emerging field to explore complex and exotic dynamics in a simple and compact form, offers a robust platform for condense matters, electromagnetic waves, optics, and acoustics by creating high‐dimensional synthetic domains. Many existing works on synthetic systems based on integrated photonics are limited to Hermitian system, while achieving dynamic control over both dissipation and dispersion of non‐Hermitian potentials still remains a challenge. In this work, a non‐Hermitian crystal is experimentally constructed in the frequency domain and demonstrate dynamic global tuning of the non‐Hermitian on‐site complex potential using an electro‐optic (EO) modulated lithium niobate (LN) racetrack microresonator and a self‐interference structure. By leveraging the mode crossing between TE and TM modes, independent linear modulation of dissipation and dispersion components, as well as joint periodic modulation, is achieved. Moreover, such structure supports the generation of a flat‐slope EO comb and fast on‐off switching at modulation frequencies up to . These results demonstrate the potential for flexible control in synthetic dimensions and offer a practical platform for optical communication, frequency comb sources, and topological photonics.