Microscaled design of the linear and non-linear optical properties of tantalum germanate glasses by thermal poling

Abstract

Sodium tantalum germanate glasses were thermally poled using microstructured metallic anodes of two distinct geometries. The topological, structural and optical characterization studies of micro-imprinted structures revealed an accurate reproducibility of the electrode patterns on the glass surface with strong edge effects between the poled and unpoled areas. Spatial reliefs of 100 nm depth were achieved and associated with glass network rearrangements due to sodium departure in the conductive anodic patterns. Second harmonic signals originating from both longitudinal and in-plane static electric fields were identified mainly near the borders of imprinted structures and related to a specific charge distribution model. Spatially controlled positive refractive index changes around 7 to 9 × 10⁻³ could be induced, opening opportunities for microscaled active optical devices operating in the middle infrared region.