Improvement the Flatness, Gain and Bandwidth of Cascaded Raman Amplifiers for Long- Haul UW-WDM Optical Communications Systems

In the present paper, the problem of multi-pumping all Raman amplifier has been investigated to obtain a maximum flatness gain and increases the bandwidth of the cascaded Raman amplifiers over a wide range of optical signal wavelengths for long-haul ultra-wide wavelength division multiplexing (UW-WDM) transmission systems due to multi-pumping wavelengths and pumping power . Three cases are analyzed where, five, eight and ten Raman pumping of special pumping powers are launched in the forward direction. We obtained a different bandwidth and different gain with flatness [1] but in the present paper we modified the flatness of the gain. The model equations are numerically handled and processed via specially cast software (Matlab). The gain is computed over the spectral optical wavelengths (1.45μm ≤ λ signal ≤ 1.65μm).