Influence of strong light beams on the nonlinear refraction and absorption coefficients of transparent materials

摘要

We explore the effective nonlinear (NL) optical response of transparent materials illuminated by strong light beams. Two different setups were used to study the influence of the numerical aperture (NA) corresponding to the collecting lens on the measured coefficients in the open- and closed-aperture Z-scan transmittance. For that, we have reproduced experiments in CS2 at 532 nm in the picosecond regime using the D4 sigma-Z-scan method. It is found that measurements of high-order NL coefficients are not possible after a limit defined by the self-focusing of light inside the cell, and that stimulated light scattering is not significant to explain alone the saturation behavior that occurs in the NL refraction measurements. Indications are given for future Z-scan-based experiments that may clarify the boundary conditions to be respected for the measurement. (C) 2019 Optical Society of America