Nonlinear refractive index variation due to varying wavelengths

An experiment and theoretical analysis have been done to measure the nonlinear refractive index n2 of LiNbO3 for different three wavelengths laser light of a continuous Ar-ion laser and observe the variation of the value and sign of the nonlinear refractive index. The Z-scan is a simple technique for measuring the change in phase induced on a laser beam upon propagation through a nonlinear material. It gives both the sign and magnitude of this phase change , which is simply related to the change in index of refraction, . For different wavelength the sign and the value of index of refraction is different. Additionally, for third-order nonlinear responses the real part of the third-order nonlinear susceptibility, , can be measured. However, Z- scan is sensitive to any nonlinear processes which results in , so that great care must be taken in interpreting data taken with this or any other nonlinear materials characterization technique.