Dependence of Z-scan measurements on the spatiotemporal pulse parameters

Abstract

We report the experimental results obtained by the closed-aperture Z-scan technique where Nd:YAG minilaser short pulses with different temporal pulse shapes have been used. It is shown that the nonlinear refractive index coefficient n2 of fused silica (one of the smallest among the condensed media) can be successfully measured using the pulses with durations of about 1 ns and energies less than 1 mJ. Very good compatibility between the values for the same samples of fused silica is obtained only if the temporal shapes of the used SBS-compressed, single longitudinal or multi longitudinal mode pulses are properly taken into account. It is also shown that spatial properties of the used beams should be taken account of properly. By these experiments we emphasize the significance of taking into account the temporal pulse shape profile for accurate determination of the nonlinear refractive index by the Z-scan technique. Keywords: Z-scan, pulse shape, nonlinear refractive index, fused silica