Comparison of different nonlinear optical characterization techniques

We present experimental and numerical results using different characterization techniques in order to obtain the third order nonlinear optical coefficients. Starting with the classical Z-scan method for materials having low optical quality, we describe also a spatially resolved Mach-Zehnder interferometry system as well as a simple imaging method using a 4f setup with a phase object at the entry. Some of these techniques are particularly appropriate to study fragile materials because the results can be obtained with a limited number of laser shots. In all cases, the nonlinearities are obtained by analyzing the intensity profiles of the image acquired with a CCD camera after nonlinear filtering through the material in a focal plane of a converging lens. Advantages and drawbacks are summarized for each technique.