Effect of Minority Species on Thermal Poling of Fused Silica Glasses

Abstract

High second-order nonlinearity (SON) in poled silica glasses [1] is of great interest for the development of linear electro-optic modulators and frequency converters monolithically integrated into optical fibres or planar glass waveguides. However, its origin [1, 2] is not fully understood. The extrinsic effects of poling time and voltage on second-harmonic (SH) generation in thermally-poled silica glass have been studied [1,3]. In particular the quadratic dependence of the maximum SH signal on the applied voltage indicated linear dependence of the SON on internal electric field [3]. There are several studies on intrinsic effects associated with defects [1, 4] and minority species such as OH [1,5] and Na [1, 6] in thermal poling of silica glasses. In this work we carried out a systematic analysis of oxygen related defects and impurities (OH and Na) in commercial fused silica glasses (without relying on their catalogue data) and discuss their effects on SON.