Measurement of fifth- and seventh-order nonlinearities of glasses

Abstract

We extend the spectrally resolved two-beam coupling technique for measurements of cubic nonlinearities of materials to include higher-order nonlinearities. The governing equations of the extended technique are derived and applied to the analysis of the experimental measurements. We report the observation of saturation of the cubic optical nonlinearity of several glasses. Fifth- and seventh-order nonlinearities are required to account for the measured nonlinear phase shifts. The observation of saturable nonlinear indices accompanied by only moderate nonlinear absorption will be relevant to some applications.