<i>Z</i>-scan technique using top-hat beams

Abstract

Top-hat instead of Gaussian beams are used in Z-scan experiments to measure nonlinear optical Kerr coefficients of materials. An empirical expression is obtained which allows direct calculation of the Kerr coefficient from measured peak–valley transmittance differences. Predictions of the model are compared with Z-scan measurement on CS2. Using top-hat beams, the sensitivity of Z-scan measurements is a factor of 2.5 greater than for Gaussian beams.