Improving the quantum efficiency of erbium-doped fiber laser by using a low-loss tipped fiber splicing process

A tipped single-mode fiber (SMF) structure is employed to reduce the fusion-splicing loss induced at the interface between SMFs and erbium-doped fibers (EDFs). By fusing the EDF and the tipped SMF with lens-like end face at once, the optimized fusion-splicing loss of as low as 0.2~0.29 dB is obtained. An improvement on splicing loss of up to 0.46 dB is obtained as compared to the conventional EDF/SMF fusion geometry. The effects of tapered angle and radius of curvature at the end face of tipped fiber on the optimization of fusion-splicing loss are compared. The erbium-doped fiber laser with maximum quantum efficiency of 2.75% is reported by using the proposed splicing technology.