Automated Z‐Scan to Distinguish Different Types of Nonlinearity Without Proposing it

Z‐scan technique is powerful method to obtain both the sign and magnitude of the complex nonlinear refractive index [1,2]. However, in order to obtain the magnitude of the nonlinear refractive index is necessary to know what type of nonlinearity present the material. In this work, we have built an all‐automated z‐scan system that is able to measure a sample under z‐scan technique and give the better numerical curve, which fits to experimental curve. The numerical z‐scan curve is obtained through one model that considers all parameters of the experimental apparatus, and especially considers to the sample like a photoinduced lens; the focal length of it has a dependence of some power m of the incident beam radius. This model is based on the propagation of Gaussian beams and in the approximation of thin lens and small distortion for the nonlinear sample. As it has been demonstrated [3] the peak and valley position difference depend of the value of m. Since each value of m correspond to a type of nonlinearity...