Experimental and theoretical analysis on pump spectral propriety of single frequency Erbium-Ytterbium co-doped fiber amplifier

The pump spectral propriety of three types of commercial 915 and 976 nm LDs on single frequency Erbium-Ytterbium co-doped fiber amplifier (EYDFA) is theoretical and experimental analyzed. The slope efficiency, ASE intensity and linewidth broadening of the wavelength stabilized or un-stabilized LDs pumped amplifier are compared in detail. The results demonstrate that 976 nm LD pumping exhibits superior to 915 nm LD in efficiency and SNR. Comparing with wavelength stabilized 976 nm LD, the wavelength un-stabilized 976 nm LD with center wavelength deviating from Yb absorption peak and over 4 nm linewidth has better performance in Yb-ASE suppression but slightly lower in efficiency and linewidth broadening. The difference between the two 976 nm LDs could be taped off by increasing the seed power or output power. This work indicate that wavelength un-stabilized 976 nm LD is more suitable for pumping high power single-frequency EYDFA to avoid the bottlenecking effect, and provide reference for the optimal pump selection.