Optical quadratic nonlinearity in corona-poled glass film waveguides

Although there has been active research on the optical quadratic nonlineari ty that appears in poled glass, its origin has not been clarified. There ha ve been many reports on bulk glass but little research on poled glass thin film waveguides. Waveguide structures are important for future applications to optical IC devices, and clarifying the origin of the nonlinearity is ve ry important. In this work we report experiments on phase-matched blue seco nd-harmonic generation in a corona-poled Coming 7059 glass film waveguide w ith a titanium sapphire laser as a fundamental wave and investigate the ori gin of its nonlinearity. After relaxation of the nonlinearity optical const ant once the poling has been measured, the analysis is performed using a bi exponential function, and the origin is elucidated by separating the fast a nd the slow relaxation components. In particular, an etching experiment has been carried out noting the latter component, and it has been shown that t he charge distribution generated in the waveguide by the poling and the int erface between the glass film and glass substrate play important roles in g enerating quadratic nonlinearity. It has also been confirmed by X-ray photo electron spectroscopy that sodium diffuses in Pyrex glass substrate as a re sult of poling. (C) 1999 Scripta Technica.