12 May 2021 Raman Scattering in fiber is a nonlinear process that converts some of the photons at fiber laser wavelength to photons at relatively longer wavelength. The higher the laser power the stronger the Raman Scattering. It must be controlled in a high-power fiber laser, or it would severely limit the laser performance. AFR ClearCut™ RSS-FBG is designed by a special Fiber Bragg Grating written onto a high-power fiber that is transparent to the laser wavelength while suppressing the unwanted Raman Scattering wavelength. It can be applied either right after a fiber oscillator or before a fiber amplifier to assure laser output of improved spectrum purity.