Measurements of Third-Order Optical Nonlinearity using Z-Scan Technique: A Review

Optical materials exhibiting a large third-order optical nonlinearity are in great demands because of their functional applications in optical limiting, optical switching, optical data storage etc. A well-known single Z-scan technique is employed to determine third-order nonlinear optical properties of nonlinear optical materials. Z-scan is a simple experimental technique to measure intensity dependent nonlinear susceptibilities of third-order nonlinear optical materials. It was originally introduced by Sheik Bahae et.al. In this technique, the sample is translated in the z-direction along the axis of a focused Gaussian beam, and the far field intensity is measured as function of sample position. Consequently, increases and decreases in the maximum intensity incident on the sample produce wavefront distortions created by nonlinear optical effects. This is a simple and sensitive single beam technique to measure the sign and magnitude of both real and imaginary part of the third order nonlinear susceptibility chi((3)) of nonlinear optical materials.