Transmission systems generally employ electronic regenerators to enhance the repeater less spans of optical links. These regenerators are complex equipment made of many optical and electronic components and hence, are less reliable. They also require power-feeding and maintenance. Optical Amplifiers, on the other hand, can boost the signal without involving unnecessary opto-electronic conversions and do not suffer from such drawbacks. Optical Fibre Amplifiers (OFA), particularly those based on the fibre doped with the rare earth ions, have received a tremendous level of interest in recent years.