High power Er3+/Yb3+ co-doped fiber amplifier of fiber length optimization

Aim to investigate the 1555 nm high power fiber amplifier with different lengths of gain fiber, a two-stage hybrid fiber amplifier structure was employed. It comprises an erbium-doped fiber amplifier (EDFA) as a pre-amplifier and an erbium/ytterbium co-doped double-cladding fiber amplifier (EYCDFA) as a post-amplifier. EDFA can pre-amplify the input signal and provide the good noise figure. EYCDFA as the main amplifier with special double-cladding configuration can couple more pump power into the system. The optimization of erbium/ytterbium co-doped fiber length was investigated experimentally and analyzed theoretically. The signal power is 10 mW, the maximum pump power of the EDFA is 318.58 mW, the total pump power of the EYCDFA is 11.47 W, the length of the EYCDF is 14 m, and the output power is 2.11 W. It shows that there is an optimal length under the certain pump power and the signal power, and the result is good for the study of high-power fiber amplifier.