Third-order susceptibility measurement by a new Mach-Zehnder interferometry technique

A new technique for measuring third-order susceptibility with a Mach-Zehnde r interferometer with a pump-probe system is proposed. The optical setup is combined with a charge-coupled device for image processing. With the propo sed method it is possible to resolve the spatial profile of a complex nonli near variation index with only one laser shot in the nonlinear material. Th erefore we can get intensity-resolved information by comparing this profile , pixel per pixel, with that of the incident beam. To verify the validity o f the method, we carry out measurements of reference materials illuminated by linearly polarized light. Good agreement is obtained with measurements m ade by various authors. An advantage of this new technique is that only one laser shot is needed to minimize the risk of damage in fragile nonlinear m aterials. (C) 2001 Optical Society of America.