Analysis and review of Erbium doped fiber amplifier

This paper is centered on four important parts of Erbium doped fiber amplifier (EDFA) optical amplifier; first is the atomic part, where it is evident and meaningful to give deep and details information of erbium spectra structure and its energy level splitting. The atomic spectra, is very crucial part in defining and understanding the amplification phenomena. The second part is based on the theoretical background of EDFA analysis, and to understand the parameters that are used for formulating the amplification rules related to spontaneous and stimulated emission. The third part is the design, where a full investigation is given to various configurations from the single pass to the quadruple pass. Vast and new designs were invented showing high-gain and low-noise-figure (NF) utilizing a new techniques. The fourth is the critical-review part, where many research papers have been reviewed to show and clarify their strong and weak points at different interpretations. This part is to specify the weakness of the classical understanding of EDFA and to describe and conceive the next generations and its characteristics.