Influence of seed power and gain fiber temperature on output linewidth in single-frequency Er3+/Yb3+ co-doped fiber amplifier

Based on the 1550 nm single-frequency Erbium-Ytterbium co-doped fiber amplifier, the output linewidth with different seed power and gain fiber temperature was experimental investigated. The results demonstrated that, to obtain the same output power, the increment of the seed power was benefit to improve the output signal to noise ratio (SNR), and to reduce the linewidth broadening. The increment of gain fiber temperature can improve slope efficiency and enhance the ASE intensity but broaden linewidth. Meanwhile, the ASE was considered as one of the reason of linewidth variation.