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. Leveraging the outstanding nonlinear optical properties and the ultra‐high spatial confinement of light, microresonators based on lithium niobate thin films have emerged as intriguing elements in various frontiers such as integrated photonic circuits and quantum photonics. In this paper, the fabrication technologies used to produce and probe lithium niobate thin‐film microresonators are summarized, together with their ingenious applications.