Coupled-resonators on thin-film lithium niobate: Photonic multi-level system with electro-optic transition

Abstract

A photonic coupled-resonator system offers exciting opportunities for investigating fundamental physics and enables broad technological applications. This is due to their unique properties: support of multiple photonic energy levels that are coupled with optical nonlinearities and their excellent reconfigurability. The coupled-resonator system has had broad applicability in, for example, optical frequency combs, dispersion engineering, optical communications, microwave photonics, and quantum information science, and also allowed the study of topological photonics and non-Hermitian physics. Recent developments in thin-film lithium niobate (TFLN) photonics have led to integrated devices that support high confinement, low propagation loss and strong electro-optic effect. Such breakthroughs yield a photonic platform offering efficient and ultrafast control of light using microwaves, excellent scalability, strong photon-photon interaction, and long photon lifetime, which is critical for photonic coupled-resonator systems. In this thesis, we will discuss our implementation of photonic coupler-resonator devices on thin-film lithium niobate. We demonstrate novel photonic devices with superior performance and previously non-existing functionalities, including high-performance frequency shifters and beam splitters, high-efficiency and broadband electro-optic frequency combs, four-dimensional frequency crystals, and frequency-domain mirrors.