4.11 W Raman fiber laser at 1239 nm using phosphosilicate fiber

Summary form only given. The advent of high-power double-clad fiber lasers (DCFL) have opened new avenues for extensive research in Raman fiber lasers to be used as pump sources at 1239 nm and at 1484 nm wavelengths. The germanosilicate has a large Raman gain coefficient but the peak Raman shift occurs only at 440 cm/sup -1/, whereas in the phosphosilicate fiber it occurs at 1330 cm/sup -1/. When the phosphosilicate fiber is pumped at 1064 nm, the first Stokes shift occurs at 1239 nm. A high-power single-mode Raman fiber laser with maximum output of 4.11 W and maximum power conversion efficiency of 47.4% at 1239 nm was realized using 700-m phosphosilicate fiber, Raman cavity formed by a pair of fiber Bragg grating (FBG) mirrors at 1239, and CW 8.4 W Yb-doped DCFL.