Using Z-scan Technology To Study The Optical Nonlinearity Of Materials

Z-scan technology is an important method studying the nonlinear optical properties. It is based on the beam distortion in space. It can be directly introduced nonlinear refractive index from the normalized transmission and the changes induced by the intersection of simple linear relationship. Nonlinear absorption of media can also be measured. Due to its convenience, high sensitivity and easy to improve and setup, it has been applied to nonlinear photorefractive effect of laser beam quality testing. This paper introduces the Gaussian decomposition theory and the diffraction theory for Z-scan. It shows in the nonlinear medium and nonlinear absorption coefficient of the refractive index measurement applications.In order to the Z-scan experiment be easier to use, we designed a computer program to achieve Z scanning system automatically, mainly including platform automation and automated data acquisition.For this the Z-scan experiment enabled to achieve the very weak nonlinear optical measurement on lower power light, use photomultiplier tube and photon counters as the energy detector. We also designed a computer program using Labview to automatically collect data.In this paper, the third-order nonlinear properties of CuCl₂(BOEP)₂ and CoCl₂(BOEP)₂ were determined by the well-known Z-scan technique at 532nm with 8-ns duration. And it was found that the third-order nonlinear refractive index of complexes is much larger than that of the ligand. In addition, the relationship between the structure and the third-order nonlinear properties of this complex had been discussed. The main reason of complex with greater nonlinear refractive index is that the complex has larger conjugated delocalized system and there are electrons shifting between ligand and metal atom. So the nonlinear properties of complex could be improved by synthesizing metal ions and the ligand whose structure contains conjugated delocalized system.