Study Of The Er/Yb Co-doped Double Clad Fiber Amplifier

Based on a deep study of the theory of double-cladding Er/Yb co-doped fiber amplifier ,this paper focuses on the analysis and comparison of two simulation models-EOF model and BPM model. BPM model has the advantages of dealing with multimode nature of cladding pump schemes and describing the effects of cladding shapes to the pump absorption; we show BPM model is more accuracy but time-consuming than EOF model by the comparison of numerical simulation and experimental results of cladding-pumped highly Er-Yb co-doped fiber amplifier,using MATLAB simulation tools. Gain performances of EOF and BPM were 28dB and 20dB respectively which are in very good agreement with result in pertinent literature,using an 8-cm-long highly doped active fiber with 1uW input excited by a 1-W 975-nm laser diode.This model is then extended to modeling ordinary doped erbium ytterbium co-doped fiber amplifier . Considering that the algorithm of BPM model is very time-consuming, we should have to make tradeoffs between accuracy and time efficiency. Thus we need make a improvement in original algorithm of BPM model. By comparing between the simulation and experimental results, this compromise is showed to be effective. Gain performances of EOF and two improved BPM were 34dB and 32.2dB and 33.4 dB respectively .Amplifier performance was 28.12 dB evaluated experimentally using an 3.2-m-long ordinary doped active fiber with 1mW input excited by two 6-W 975-nm laser diode.Though there is a huge gap between simulation and experiment results,The improved algorithm of the BPM model is more accuracy than that of the EOF model while the simulation time is still in acceptable range. This work may play an important role in improving performance of double cladding Er/Yb co-doped fiber amplifier .