Effects of stimulated Brillouin scattering on gain saturation in discrete Raman fiber amplifiers

The generation of SBS in discrete Raman gain must be considered along with the problem of limited gain per unit pump power when developing a practical Raman amplifier. In this paper, we focus on discrete Raman amplifier with 15 km dispersion compensating fibers (DCFs). The gain saturation of both forward and backward pumping schemes have been considered and compared. As the pump power increased, the SBS threshold decreased and the reflected power increased dramatically. The 7th SBS stokes have been observed when the pump power is 490mW. The experimental results clearly indicate that the SBS effects produced a saturation of the Raman gain.