Self‐Powered Lithium Niobate Thin‐Film Photodetectors

Abstract Thin‐film lithium niobate platform, namely lithium‐niobate‐on‐insulator (LNOI), brings new opportunities for integrated photonics, taking advantages from both outstanding crystalline properties and special structural features. The excellent properties of LNOI have triggered development of a variety of on‐chip photonic devices for light generation and manipulation. However, as an indispensable component for photonic circuit with full functionalities, the thin‐film photodetector lacks in portfolios of LNOI‐based devices due to standing obstacles of low electrical conductivity and poor photoelectric conversion ability. Here, a self‐powered broadband LNOI photodetector based on enhanced photovoltaic effect, benefitting from encapsulated plasmonic nanoparticles and doped silver ions, is reported. Maximum responsivity of 0.25 A W −1 and detectivity (1.56 × 10 14 Jones) are achieved. First‐principle calculations and electric‐field simulation reveal intrinsic mechanisms and crucial roles of plasmonic nanoparticles and silver ions on photocurrent generation and collection. This work opens an avenue to develop high‐performance on‐chip LNOI photodetectors, offering a conceivable means toward multiple‐functional photonic circuits.