Fiber Raman amplifiers (FRAs) are attractive for ultra wide dense wavelength division multiplexing (UW-DWDM) transmission systems due to their advantages of broad amplification bandwidth and flexible central wavelength. With recent developments of optical pump sources with high power near 1.4 μm wavelength and highly nonlinear fiber having a peak effective Raman gain coefficient, more than ten times that of conventional single mode fiber, distributed FRAs (DFRAs) are emerging as a practical optical amplifier technology, especially for opening new wavelength windows such as the short and ultra long wavelength bands. Optical pump powers required for Raman amplification were significantly higher than that for erbium-doped fiber amplifier (EDFA), and the pump laser technology could not reliably deliver the required powers. However, with the improvement of pump laser technology, Raman amplification is now an important means of expanding span transmission reach and capacity. In the present paper, we have deeply investigated the proposed model for optical DFRAs in the transmission signal power and pump power within Raman amplification technique in co-pumped, counter-pumped and bi-directional pumping direction configurations through different types of fiber cable media. The validity of this model was confirmed by using experimental data and numerical simulations.
Key words: Distributed fiber Raman amplifier, signal power, pumping power, forward pumping, different fiber media, backward pumping, bidirectional pumping configuration.
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