Researchers have developed an on-chip geometrical-optics resonator framework that achieves intrinsic quality factors above one million, according to research published in Nature Communications on September 14, 2026. The platform operates distortion-free at roughly 10 times higher optical power than traditional systems.
Conventional waveguide optical resonators face persistent limits from low damage thresholds, restricted coupling tunability, and stochastic resonance. To resolve those issues, the geometrical-optics resonator emulates free-space reflection and thin-film coupling directly on an integrated chip.
Ultra-wide waveguides form the basis of the system, paired with total internal reflection mirrors and frustrated total internal reflection couplers. This setup enables tunable microwave photonic filters while avoiding the physical constraints seen in standard micro-resonators.
Photonic molecules and lattices
Coupled resonator designs also permit cascaded networks for spectral engineering. Demonstrated photonic molecules created with the system produced dynamically adjustable mode splitting of 0.49 free spectral range, nearing theoretical limits. In addition, the team implemented Floquet topological photonic insulators built from 1,281 resonator lattices, which supported robust edge modes against defects across a broadband continuum.
Chunlei Sun and Kangjian Bao contributed equally as co-first authors on the study, working alongside co-authors including William Shieh, Min Qiu, and Lan Li. The research team was based primarily at Westlake University, with collaborators from Zhejiang University and the Institute of Microelectronics of the Chinese Academy of Sciences.
Facility support came from the Westlake Center for Micro/Nano Fabrication and Instrumentation, the Service Center for Physical Sciences at Westlake University, and the ZJU Micro-Nano Fabrication Center. Nature Communications received the peer-reviewed manuscript on August 27, 2025, and accepted it on August 13, 2026.
