الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Fiber Raman amplification using the transmission line is a promising technology to increase the repeater distance as well as the capacity of the communication systems. The most important feature of fiber Raman amplifier is the stimulated Raman scattering, which is essentially based on Raman effect discovered by Raman in 1928. He noticed the appearance of additional spectral lines after a monochromatic light passed through transparent materials. There are two types of Raman amplifiers: discrete Raman amplifier and distributed Raman amplifier. This study, describes the net gain of discrete Raman amplifier as a function of fiber length at different pump configurations. Also, it presents the amplified spontaneous emission (ASE) noise power analytically and numerically of the distributed Raman amplifier (ORA) as a function of fiber length at different pump configurations: forward pumping (co¬pumping), backward pumping (counter-pumping) and bidirectional pumping.
Finally, we present and proposed a new trend to calculate optical signal to noise ratio (OSNR) for ORA as a function of fiber length, and its variation with input pump power and input signal power at different pump configurations. We reached a lower gain and ASE noise power in case of forward pumping, a higher gain and ASE noise power in backward pumping and a medium gain and ASE noise power in bidirectional pumping. We observe that, in all three cases of pumping, the OSNR decreases exponentially versus span length. It is found that, forward pumping provides the highest OSNR. However, backward pumping is often employed in practice because of other considerations such as the transfer of pump noise to signal which provides the smallest OSNR between other pumping configurations while the bidirectional pumping provides the moderate OSNR between the others. The OSNR increases exponentially with input pump power and decreases exponentially within input signal power.