A theoretical analysis of amplification characteristics of bi-directional erbium-doped fiber amplifiers with single erbium-doped fiber

Based on the discussion of the structure scheme of bi-directional EDFA (Bi- EDFA) with single erbium-doped fiber (EDF) which can efficiently suppress t he internal reflections, a rate equation model for the Bi-EDFA is developed to calculate the signal gain, pump absorption and output noise spectrum. T he effects of numbers of signals, pumps of arbitrary direction, amplified s pontaneous emission (ASE) and inherent loss are taken into account. Using t his model, the influence of EDF length, input signal power, pump style and pump power on the gain characteristics of the Bi-EDFA is analyzed. The forw ard and the backward noise figures versus bi-directional input signal power for different pump styles are also investigated. With these results, the o ptimal design for Bi-EDFAs in optical fiber communication systems and netwo rks can be achieved. (C) 1999 Elsevier Science B.V. All rights reserved.