The influence of different seed sources on stimulated Raman scattering in fiber amplifiers

Fiber based cw laser systems nowadays reach output powers of several kW and often limited by nonlinear effects such as Stimulated Raman Scattering (SRS) [1]. Previously, the influence of the grating spectral width of fiber oscillators on SRS has been investigated [2]. Here we go one step further and compare different seed laser systems that are amplified to a kW level in a single fiber amplifier with regard to SRS. To force SRS, the fiber is made as long as 40m and co-pumped. For the comparison, one and two single-frequency diode laser (ECDL), a commercial fiber laser and a fiber oscillator with varying oscillator length are amplified to about 700W output power as shown in Fig. 1. Detailed comparison of the different seed sources leads to new insights on SRS.