Induced refraction rings from cumarine materials

We study de nonlinear optical properties of organic materials. Multiple rings appear as a CW Ar laser passes through a nonlinear organic liquid. The rings formation is due to spatial self-phase modulation and is observed with 50 mW of continuous wave of Ar laser. We show the dependence between power and rings formed. As a first approximation to value the nonlinear refractive index we use the number of the rings and power of laser in a cell of 2 mm of length.