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arXiv · 2512.22779

High-Q Lithium Niobate Microring Resonator with Electro-Optically Reconfigurable Coupling Strength

Yuan Ren·Yong Zheng·Ruixue Liu·Boyang Nan·Ziyao Zhuang·Rongbo Wu·Min Wang·Ya Cheng
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Abstract

The development of sophisticated integrated photonic circuits demands microresonators that combine exceptional optical confinement with dynamic operational flexibility. Here, we demonstrate a racetrack resonator on the thin-film lithium niobate platform that achieves an electro-optically tunable coupling strength while maintaining a stable, high intrinsic Q factor on the order of 10^6. By incorporating a Mach-Zehnder interferometer into the coupling region, the device facilitates a continuous and reversible transition across the entire coupling spectrum from under-coupling and critical coupling to deep over-coupling. To ensure high spectral purity, we employ Euler bends to facilitate an adiabatic transition between the straight and curved waveguide sections. This design effectively suppresses the excitation of higher-order modes, resulting in a clean transmission spectrum characterized by exclusive fundamental mode operation. At the critical coupling point, the resonator exhibits a high extinction ratio exceeding 30 dB. The integration of stable ultra-high Q, single-mode purity, and full-range coupling reconfigurability positions this device as a vital component for adaptive microwave photonics, high-efficiency nonlinear optics, and programmable quantum photonic networks.

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Yuan Ren, Yong Zheng, Ruixue Liu, Boyang Nan, Ziyao Zhuang, Rongbo Wu, Min Wang, Ya Cheng. 2025-12-28. High-Q Lithium Niobate Microring Resonator with Electro-Optically Reconfigurable Coupling Strength. https://arxiv.org/abs/2512.22779

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