Nonlinear refractive index of fluoride crystals

Abstract

Nonlinear refractive-index coefficients of 11 fluoride crystals were measured at 1064 nm using time-resolved interferometry. A simple empirical expression is given for the index nonlinearity in terms of the d-line refractive index and Abbé number which agrees with measured values for both fluoride crystals and optical glasses and which can be used to estimate index nonlinearities. Since the nonlinear indices of several fluoride crystals are among the smallest reported for solids, these materials are of interest for transmitting optical components in high-power laser systems where self-focusing is important.