Experimental and numerical optimization of a fiber Raman laser

We present an experimental test of a recently published model that describes a nested fiber Raman cavity taking into account all interactions between forward and backward traveling waves. The experiment consists in the realization of a one-stage fiber Raman laser, pumped at 1090 nm, using one Stokes shift to produce output radiation at 1150 nm. The conversion efficiency measured as a function of input power and fiber length is successfully compared with the numerical results. We also apply the model to the comparison between the performance of phosphosilicate (PS) and germanosilicate (GS) fibers. We have considered a five-step Raman laser using a GS fiber with a 1117 nm pump, and a two-step Raman laser using a PS fiber with a 1061 nm pump, both emitting at 1480 nm. In the optimum configuration, the simpler PS fiber laser presents a conversion efficiency about 15% lower than that of the GS fiber laser and uses a fiber length 40% larger.