Fiber attenuation irregularities and simulation of Raman amplification band

Analytical expression of wavelength dependence of signal attenuation coefficient in the range of S+L+C telecommunication window is obtained using polynomial approximation in single-mode silica fibers: DCF, TrueWaveRS^TM and pure SMF. It allowed correcting the threshold conditions of Raman amplification. It is shown that Raman gain threshold increased adjusted for wavelength irregularity of attenuation in comparison with threshold at constant attenuation of optical wave. It led to significant narrowing of Raman amplification band by-turn, especially up to a few THz in DCF. Presented technique of simulation of Raman amplification band is useful for designing of wideband fiber Raman amplifiers.