The design of active optical devices integrating second-order nonlinear (SONL) optical responses typically relies on the use of dielectric crystalline materials such as lithium niobate (LN) or semi-conductors such as GaAs. Despite high SONL susceptibilities, these materials present important geometry constrains inherent to their crystalline nature limiting the complexity of the designed photonic systems. Conversely, amorphous materials are versatile optical media compatible with broad platform designs possessing a wide range of optical properties attributable to their composition flexibility. Demonstrated here for the first time in an amorphous inorganic material, we report a magnitude of SONL optical susceptibility (χ (2) =29 pm/V at 1.06 µm) comparable to that of LN single crystal. By using a thermo-electrical imprinting process, fine control of the induced uniaxial anisotropy is demonstrated at the micrometer scale. This work paves the way for the future design of integrated nonlinear

Structure, linear and nonlinear optical properties of glasses in the ternary system (90-x)GeO2-10Na2O-xTa2O5 have been investigated. These glasses exhibit a wide transparency window from 350nm to 5500nm and refractive index ranging from 1,78 to 1,93. Upon a thermal poling treatment under nitrogen atmosphere using increasing poling voltages, SHG quantitative measurements were performed and have confirmed the electro-optical origin of the second order optical responses,  (2) values ranging from 0,06pm/V to 0,3pm/V were obtained depending on the poling conditions and glass composition. SHG/Raman correlated microscopy measurements allowed to identify the structural changes within the poled layer and pointed out that sodium depletion lead to a more connected glass network through cross-linking bonds such as Ge-O-Ge and Ta-O-Ta bonds. A deviation from a pure electro-optical second order response is observed for the highest poling voltage. In this particular case, a linear optical birefringence and a structural  (2) might have to be taken in account to describe accurately the polarized layer optical properties.

Herein, our attention is focused on the second‐order optical properties of thermally poled sodo‐niobate amorphous thin films through an original methodology that combines both macroscopic and microscopic second harmonic generation techniques. By probing the geometry and the magnitude of the second‐order nonlinear (SONL) optical response at different scales, a key aspect of thin film's poling mechanisms compared with bulk glasses is demonstrated that lies in the appearance of a charge accumulation at the film/substrate interface and that is described by the Maxwell–Wagner effect. A way to minimize this effect is then proven by promoting an induced built‐in static field in the plane of the film using a microstructured electrode. A SONL optical susceptibility as high as 29 pm V−1 is measured and its geometry and location are controlled at the micrometer scale; it constitutes an improvement of at least one order of magnitude compared with other poled amorphous inorganic materials and is comparable with that of lithium niobate single crystal.