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

摘要

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 in a Z-scan set up we demonstrate an improvement in sensitivity of the method that is suitable also 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 C_5 that describes defocus as function of the axial sample position. Here the new method is demonstrated by evaluating the nonlinear optical properties of CS_2 and Coumarin as standard materials, using a 1 KHz repetition rate Ti-Sapphire laser delivering ～80fs pulses.