Gain and noise tilt control in multi-wavelength bi-directionally pumped Raman amplifier

We proposed an optimized bi-directional pumping scheme that realized a good flatness of Raman gain and variety of optical noise figure spectra, simultaneously. We used previously developed low-noise pump lasers for forward-pumping. By means of the proposed scheme comprising five pump wavelengths, about 2.3 dB variation of wavelength dependence of noise figure are demonstrated at a fixed flat Raman gain of 9 dB for 76 km of single mode fibre.