Theoretical analysis of erbium doped fiber amplifier

Deep theoretical descriptions of erbium doped fiber amplifier (EDFA) is proposed and explained in this paper. An amplification is occurred for a signal passes through the core doped with erbium ion (Er⁺³) under the effect of pump, absorption, stimulated, and spontaneous emission. The stimulated emission will occur exactly at the same wavelength of the past signal but the spontaneous will occur at wide range of wavelengths. Different models were proposed with different harmonization to experimental results. These existed models are used to much the experiment but due to the huge number of parameters affecting the output all these pure theory models becomes far from the exact results and an adder of complexity and misunderstanding of the real phenomena. In this paper we are trying to understand and verify the basics of laser and amplifications in EDFA, and how the beginner in this field can conceive the laser and amplifier phenomena.