Theoretical study of high order and saturable Kerr media nonlinearities in Z-scan

Abstract

Based on Fresnel–Kirchhoff diffraction theory, the effect of high order nonlinearities and saturable Kerr media in Z-scan experiments are theoretically investigated. Analytical expressions were obtained for the Z-scan curve, which can be strongly affected by the pump intensity. Moreover, empirical relationships were found to describe the intensity dependence of the peak-valley distance and the transmittance difference, allowing an accurate determination of parameters such as high-order nonlinearities, the saturation intensity and the confocal parameter.