Interferometric Estimation of Nonlinearity in GRIN Optical Fiber

In many industrial applications, coupling high power laser beam into multi-mode graded-index fiber (GRIN) is an important issue especially when deeper penetration and speed cutting/welding processes are required. With increasing the laser power, nonlinear effects such as self-focusing takes place leading to a catastrophic damage for optical fibers. Construction of robust high power fiber-laser systems still need to analyze the different parameters that affect the nonlinear response of the fiber material and its waveguiding conditions. Due to its high spatial resolving power, interferometry is used to study the efect of waveguide and material dispersion profiles, and the central core-index dip on the Kerr nonlinear index profiles of GRIN fiber.