Microresonators in Lithium Niobate Thin Films

Leveraging the outstanding nonlinear optical properties and the ultra-high spatial confinement of light, microresonators based on lithium niobate (LN) thin films have emerged as intriguing elements in various frontiers such as integrated photonic circuits and quantum photonics. A number of applications have been realized based on LN thin-film microresonators toward various on-chip devices. In this paper, the recent advances of microresonators based on LN thin films are reviewed, including essential techniques used in fabrication/characterization and a detailed overview of applications, ranging from frequency conversion, electro-optic modulation, frequency combs, microwave-to-optical transducers, quantum photonics, to lasing. A short summary and perspective is presented to indicate possible research topics related to LN thin-film.