Journal ArticleTwenty-nine million intrinsic <i>Q</i> -factor monolithic microresonators on thin-film lithium niobateZhu, Xinrui; Hu, Yaowen; Lu, Shengyuan; Warner, Hana K; Li, Xudong; Song, Yunxiang; Magalhães, Letícia; Shams-Ansari, Amirhassan; Cordaro, Andrea; Sinclair, Neil; Lončar, Marko<p>The recent emergence of thin-film lithium niobate (TFLN) has extended the landscape of integrated photonics. This has been enabled by the commercialization of TFLN wafers and advanced nanofabrication of TFLN such as high-quality dry etching. However, fabrication imperfections still limit the propagation loss to a few dB/m, restricting the impact of this platform. Here, we demonstrate TFLN microresonators with a record-high intrinsic quality (<italic>Q</italic>) factor of twenty-nine million, corresponding to an ultra-low propagation loss of 1.3 dB/m. We present spectral analysis and the statistical distribution of<italic>Q</italic>factors across different resonator geometries. Our work pushes the fabrication limits of TFLN photonics to achieve a<italic>Q</italic>factor within 1 order of magnitude of the material limit.</p>Optica2024-01-0110563695Photonics Research128A632327-9125https://doi.org/10.1364/PRJ.5211722137723National Science Foundation