All-fiber high-power Er3+-Yb3+ codoped amplifier based on double-cladding small core fiber and multi-mode pump diode at 915 nm is experimentally demonstrated.By seeding the amplifier with a narrow linewidth signal from a distributed feedback(DFB) laser diode,the maximum output power of 2.14 W has been obtained with a slop efficiency of 27.2%.No evident stimulated Brillion scattering(SBS) or other nonlinear effects were observed in the experiment.The amplifier can be used as the front stage of a ...