Toward 3D Integrated Photonics Including Lithium Niobate Thin Films: A Bridge Between Electronics, Radio Frequency, and Optical Technology

Lithium Niobate (LN) was the dominant material platform for integrated optics for several decades, based on its superior electro-optical and nonlinear (NL) optical properties. However, silicon photonics, despite its less favorable intrinsic properties, has been rapidly adopted by industry to support a smaller device footprint; higher component density; lower energy consumption; and compatibility with high-volume, low-cost silicon microelectronics manufacturing processes. However, the performance of LN integrated optics remains unsurpassed by silicon photonics. By adopting a thin-film technology and hybrid waveguide designs, LN and silicon photonics could both be integrated as optoelectronics layers in future 3D integrated microsystems. We discuss the multilayer device architecture vision and recently reported enabling research progress in thin-film LN technology and its integration into the silicon photonics system.