Stimulated Raman Scattering in Multi-Mode Fibers and Its Application to Beam Cleanup and Combining

Laser beam cleanup properties of stimulated Raman scattering (SRS) in a multi-mode fiber have been characterized. It is shown that a fiber, which supports propagation of a highly aberrated pump beam, can generate a Gaussian-like Stokes beam consisting of one or more orders of Stokes components. The beam cleanup properties are found to be similar to those of stimulated Brillouin scattering, which are briefly reviewed herein. The dramatic enhancement in beam quality achievable through SRS clearly demonstrates the potential utility of fiber-based Raman beam cleanup/combining devices for laser brightness scaling.