Effect of stimulated Brillouin scattering on the gain saturation of distributed fiber Raman amplifier and its suppression by phase modulation

Zhang Yi-Chi^a),^b), Chen Wei^a),^b), Sun Shi-Lin^a),^b), Meng Zhou†^a),^b)

Results of index-fixed phase modulation experiments for forward-pumped DFRAs, showing (a) curves of on–off gain versus input signal power with various modulation frequencies and a fixed modulation index, (b) enhancements of gain saturation power versus phase modulation frequency with a fixed modulation index of 1.380, and (c) backscattering optical spectra with various modulation frequencies and a fixed modulation index (the input signal power is 3 dBm).