ABSTRACT: We report here the efficiency improvement in a fiber Raman laser by splicing to it short pieces of 10000-ppm Yb3+-doped fibers. The amplified spontaneous emission produced by the doped fiber started the stimulated Raman scattering earlier
than the spontaneous scattering in the 350-m silica-fiber cavity. In the best case, when splicing to the cavity 127 cm of
doped fiber, the pump threshold decreased from 2.9 down to 1.27 W, representing a 56% improvement. This power was close to
the theoretical minimum of 1.25 W for very long fibers. The second stokes signal (1175 nm) was only present when the doped
fibers were inserted. At 4-W pump, the non-doped cavity delivered 2 W of first stokes signal (1117 nm) that represent a 50%
efficiency compared to ∼3 W delivered (∼75%) when a 34-cm doped fiber was inserted. This improvement is intended to reduce
the cost of fiber Raman lasers because less powerful sources or shorter fibers are necessary to produce more stokes components.
Laser Physics 05/2012; 19(5):1017-1020. · 3.61 Impact Factor