الفهرس 
Chapter One: IntroductionOnly 14 pages are availabe for public view
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Abstract
In this work, the problem of multi-pumping Raman amplifiers has been investigated to study the relation between the number of optical amplifiers, gain and the flatness of the gain and also we discuss the relation between the cascaded optical amplifiers and the bandwidth 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 to modified the flatness of the gain and obtained a large and broadened bandwidth [by using different models of cascaded Raman amplifier]. We processed: the gain coefficient, the gain coefficient per watt and the differential .
Also due to the benefits of Raman amplifier for Long-Haul UW-WDM Optical Communications Systems we have investigated the effects of many parameters on the gain and bandwidth of Raman amplifier such as: pumping wavelength, offset wavelength, the relative refractive index difference and the number and location of the cascaded units used in the amplifier model design.
In this work, the distributed multi-pumping Raman amplifier has been studied and analyzed by testing two designed algorithms of amplifier to obtain the gain of maximum flatness and bandwidth for different models to achieve simultaneously:
1- Wide BW that is used in modern communication systems which uses UW-WDM.
2- Maximum repeater spacing.
The model equations are numerically handled and processed via a specially cast software. The gain is computed over the spectral optical wavelengths (1.45μm ≤ λsignal ≤ 1.65μm).
It is found that if the number of optical amplifiers increases, the bandwidth increases, but flatness depends on the position of each amplifier corresponding to the others. The parameters affecting the amplifier gain are core radius, relative refractive index difference, pumping wavelength and pumping power. Finally, the differential gain, total gain coefficient and gain per watt for the different cases are also studied.