The processing of backward amplified spontaneous emission in a bismuth-based erbium-doped fiber amplifier

A hybrid structure of broadband bismuth-based erbium-doped fiber amplifier(Bi-EDFA) with an optical isolator and an optical circulator is designed,respectively.The effects on performance of Bi-EDFA are presented theoretically when its backward amplified spontaneous emission(ASE) is processed.Under the conditions of the multi-wavelength signal of C+L band is inputted simultaneously,the each signal gain can be improved and noise figure of Bi-EDFA can be decreased by means of suppressing the backward ASE with an optical isolator inserted in the bismuth-based erbium-doped fiber(Bi-EDF).The long-wavelength band signal gain can be enhanced evidently with only a little increasing of noise figure as an optical circulator is utilized to direct the unwanted backward ASE of BiEDFA to pump an un-pumped Bi-EDF.The theoretical simulation is in a good agreement with the reported experimental result.The above results will provide practical significance for a new design and application of Bi-EDFA.