On-Chip Electro-optically Tunable Narrow Linewidth Brillouin Microlasers Implemented in Thin Film Lithium Niobate
Phys. Rev. Lett. 136, 093801 – Published 2 March, 2026
DOI: https://doi.org/10.1103/nw4m-s6xy
Abstract
On-chip narrow linewidth microlasers with real-time wavelength tunability are highly desirable for various applications, including precision metrology, quantum technology, and coherent information processing. Although significant progress has been made by various groups in recent years [M. Li et al., Nat. Commun. 13, 5344 (2022); V. Snigirev et al., Nature (London) 615, 411 (2023); X. Zhang et al., Appl. Phys. Lett. 124, 131101 (2024); S. Gundavarapu et al., Nat. Photonics 13, 60 (2019)], realizing such microlasers, especially within compact microresonators with a small footprint, remains a challenge. In this Letter, we overcome these hurdles and demonstrate on-chip electro-optically tunable Brillouin microlasers in compact lithium niobate on insulator microdisks with diameters of 31.5 and by utilizing cross-polarized stimulated Brillouin scattering configuration. A quasicontinuum band of bound shear mechanical modes inside the suspended microdisk is revealed, allowing feasible phase matching of stimulated Brillouin lasing. We achieve efficient cross-polarized optomechanical coupling and Brillouin lasing via the significant photoelastic tensors of lithium niobate (e.g., ). This approach yields a 118-Hz short-term integral linewidth, a 0.16-Hz intrinsic linewidth, and a comparatively low threshold power of 3.15 mW. A real-time electro-optic tuning with a tuning efficiency of is also achieved, further showcasing potential of the lithium niobate on insulator platform for next-generation tunable photonic systems.
