Electrically Micro‐Polarized Amorphous Sodo‐Niobate Film Competing with Crystalline Lithium Niobate Second‐Order Optical Response

Abstract

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

Second‐Order Optical Response in Electrically Polarized Sodo‐Niobate Amorphous Thin Films: Particularity of Multilayer Systems

“…The poling efficiency in the structured zone has been reported and discussed in a previous study. [ 29 ]…”

“…Overall, the effect of the poling treatment in the homogeneous zone in terms of structure and composition is similar to the one that was previously reported in the structured zone. [ 29 ]…”

“…The refractive indices were determined in a previous work. [ 29 ] The SIMS measurements (Figure 2b) have shown that the whole film's thickness is poled. For the simulations, we have neglected the substrate's contribution to the SHG response and considered that the SHG active layer's thickness was that of the film.…”

“…Recently, we have proposed a new approach to address this issue, consisting of: 1) the development of new amorphous thin film optical materials whose composition lies outside of the classical glass forming regions, prepared using radio frequency (RF) sputtering deposition of sodium niobate compositions [ 29 ] and 2) a thermoelectrical imprinting process using structured electrodes demonstrating control at the micrometer scale of the localization and the geometry of the induced anisotropy. [ 23,29,30 ] These sodo‐niobate amorphous thin films have been found to be particularly well adapted to the thermal poling process as they exhibit second‐order optical susceptibilities ( χ (2) ) greater than 20 pm V −1 corresponding to an improvement of one order of magnitude as compared with poled glassy systems and being now close to the targeted property of lithium niobate. [ 29 ]…”

“…[ 23,29,30 ] These sodo‐niobate amorphous thin films have been found to be particularly well adapted to the thermal poling process as they exhibit second‐order optical susceptibilities ( χ (2) ) greater than 20 pm V −1 corresponding to an improvement of one order of magnitude as compared with poled glassy systems and being now close to the targeted property of lithium niobate. [ 29 ]…”