Interferometric Z-scan method for thermo-optical effect studies

Abstract

We demonstrated a new approach to measuring third-order nonlinear optical effects using an experimental setup incorporating both Z-scan and Mach-Zehnder interferometer methods. This method could be especially purposive for thermo-optical effect studies as it can simultaneously probe thermal gradient profile as well as absolute temperature changes induced by an optical beam. The experimental setup was tested using chloroform. Experimental measurements were carried out using 1064 nm Nd:YAG laser with 8 ns pulse width and 40 kHz pulse repetition rate. The measured nonlinear refractive index of chloroform was mainly induced by the thermo-optical effect. As thermo-optical response depends on beam size at focal length, measurements were carried out with 35 mm and 125 mm focal length lenses. Measured nonlinear refractive index values of Z-scan and interferometric measurements gave the same value indicating that this method can be used for thermo-optical effect studies.