Integrated electro-optics on thin-film lithium niobate

Electro-optics serves as the crucial bridge between electronics and photonics, unlocking a wide array of applications ranging from communications and computing to sensing and quantum information. Integrated electro-optics approaches in particular enable essential electronic high-speed control for photonics while offering substantial photonic parallelism for electronics. Recent strides in thin-film lithium niobate photonics have ushered revolutionary advancements in electro-optics. This technology not only offers the requisite strong electro-optic coupling but also boasts ultra-low optical loss and high microwave bandwidth. Further, its tight confinement and compatibility with nanofabrication allow for unprecedented reconfigurability and scalability, facilitating the creation of novel and intricate devices and systems that were once deemed nearly impossible in bulk systems. Building upon this platform, the field has witnessed the emergence of various groundbreaking electro-optic devices surpassing the current state of the art, and introducing functionalities that were previously non-existent. This technological leap forward provides a unique framework to explore various realms of physics as well, including photonic non-Hermitian synthetic dimensions, active topological physics, and quantum electro-optics. In this review, we present the fundamental principles of electro-optics, drawing connections between fundamental science and the forefront of technology. We discuss the accomplishments and future prospects of integrated electro-optics, enabled by thin-film lithium niobate platform.