Analysis of gain and noise characteristics of O-band Bi-doped fiber amplifier under different pumping schemes

Abstract

In this paper, the gain and noise characteristics of bismuth-doped fiber amplifiers in O-band (1260–1360 nm) under forward, backward and bidirectional pumping are comprehensively compared and optimized using numerical models. The validity of the model is verified. The results show that (1)the signal power is changed within a limited range does not have an effect on the noise figure. However, the noise figure will be worse while the power continues to increase, and the magnitude of the change is most pronounced under the backward pumping scheme. With an increase in signal power from − 25 dBm to − 10 dBm, the noise figure is relatively flat under all pumping schemes. While increasing from − 10–0 dBm, the noise figure under backward pumping increased by 0.9 dB; (2)Only if pump power is below a certain threshold, the gain obtained under bidirectional scheme is significantly higher than under forward and backward.With larger pump power, the gain obtained under all pumping schemes is almost the same. With pump power less than 1.2 W, the gain under bidirectional scheme is 0.9 dB higher than that under forward and backward schemes. With more than 1.2 W, the gain difference between bidirectional and forward and backward is only 0.2 dB. The analysis provides guidance for the selection and optimization of pumping structures in BDFA, thus helping to improve the performance of O-band transmission systems.