A novel tipped fiber structure for reduction of the fusion-induced coupling loss between erbium-doped and single-mode fibers

We report a nearly 2-time improvement on the quantum efficiency of erbium-doped fiber laser by fusing the erbium-doped fiber with a tipped single-mode fiber with lensed endface. Maximum output power and quantum efficiency under pumping of 70 mW are 2 mW and 2.7% respectively.