Second Harmonic Generation in Sodium Tantalum Germanate Glasses by Thermal Poling

Category : Publications | Date : Oct 9, 2019

Gael Poirier, Marc Dussauze, Vincent Rodriguez, Frédéric Adamietz, Lara Karam, Thierry Cardinal, and Evelyne Fargin


J. Phys. Chem. C 2019, 123, 43, 26528–26535


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 350 to 5500 nm and refractive index ranging from 1.78 to 1.93. Upon a thermal poling treatment under nitrogen atmosphere using increasing poling voltages, second harmonic generation (SHG) quantitative measurements were performed and have confirmed the electro-optical origin of the second-order optical responses; χ(2) values ranging from 0.06 to 0.3 pm/V were obtained, depending on the poling conditions and glass composition. SHG/Raman correlated microscopy measurements allowed identification of the structural changes within the poled layer and pointed out that sodium depletion led 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 χ(2) might have to be taken into account to describe accurately the polarized layer optical properties.