Demonstration of SRS filtering at the output of 2kW fiber laser by CTFBG

Chirped and tilted fiber Bragg gratings (CTFBGs) have attracted a lot of attention for stimulated Raman scattering (SRS) suppression in high-power fiber laser systems in past years. Here, we fabricate CTFBGs in large-mode-area double cladding fibers and demonstrate its application in a 2-kW fiber laser for SRS filtering at the system’s output. A maximum Raman suppression of about 17 dB is obtained at the central wavelength, and the insertion loss is smaller than 0.2 dB for signal laser. In addition, no obvious degradation of laser beam quality is observed. Better suppression effect could be achieved by broadening the rejection bandwidth of the CTFBGs in the future.