Advanced Microscale Patterning of Strong Second-Order Optical Nonlinearity in Sodo-Niobate Amorphous Thin Films through Imprinting Thermo-Electrical Poling Process

A thermo-electrical imprinting process has been employed to induce second-order optical nonlinear (SONL) response in amorphous sodo-niobate optical thin films. By characterizing the geometry and the magnitude of the SONL response, a key aspect of thin film's poling mechanisms compared with bulk glasses was established. This lies in the appearance of a charge accumulation at the film/substrate interface, described by the Maxwell–Wagner effect. A way to minimize this effect was then proven by promoting an induced built-in static field in the plane of the film using a microstructured electrode. A SONL susceptibility as high as 29 pm/V was measured, and its geometry and location were controlled at the micrometer scale. This work paves the way for the future design of integrated nonlinear photonic circuits based on amorphous inorganic poled materials.