Dependence of the induced optical second-order nonlinearity profile of poled silica samples on poling conditions

Abstract

Recently, we reported a fast and simple iterative inverse Fourier transform algorithm that allows for the first time to determine the second-order optical nonlinearity profile of thin films uniquely from a classical Maker fringe measurement. In this work, we have applied this novel technique to study the quantitative effects of the poling time and poling field on the second-order nonlinearity profile of thermally poled silica (Infrasil) samples. This study has enabled us to optimize the poling conditions and produce a record peak nonlinear coefficient d33 of 1.35 pm/V (poling at 9.6 MV/m and 280 °C for 15 minutes). This coefficient is 70% larger than typical values reported for conventional poling conditions (~5 MV/m for 15 minutes). This investigation also yielded values for a number of interesting poling parameters, in particular the diffusion depth of the positive species injected into the sample during poling as a function of poling conditions. These results are important for understanding the physics of the induced nonlinearity and for optimizing future optical devices in poled silica.