We analyze as to how an optical amplifier of different doping ions such as Erbium, ytterbium and Er-Yb co-doped, will respond when its parameters are varied, in terms of its output power in dB. The parameters include the Pump power, doping concentration and the signal power. The results demonstrate that EDFA requires half the amount of pump power than that required for YDFA and further Er-Yb amplifiers help extend EDFA from C-band (1530 – 1565) to L-band (1565nm-1625nm). © 2015, National Institute of Optoelectronics. All rights reserved.