Novel high-sensitivity Z-scan technique based on a Hartmann-Shack wavefront sensor

Here we report on a new variation of the Z-scan method to characterize the third-order optical nonlinearity of photonic materials. By exploiting a Hartmann-Shack wavefront sensor on a Z-scan set up we demonstrate an improvement in sensitivity of the method. We also show that the method is suitable for the evaluation of samples having strong nonlinear absorption. The nonlinear indices of refraction values have been obtained by analyzing the variation of the fifth-order Zernike coefficients C5 that describe defocus as function of the sample position on the Z-scan setup. Here the method is demonstrated by evaluating the nonlinear optical properties of CS2 and Coumarin as standard materials, using a 1 KHz repetition rate Ti-Sapphire laser delivering 100fs pulses. © 2010 Copyright SPIE - The International Society for Optical Engineering.