This paper begins with the introduction of the basic principles of the cladding pumping technology

the technical approach for the realization of high power amplifiers by using the ytterbium-erbium co-doped dual-clad fiber pumped by the high power multimode pump laser and the comparison with that for the conventional Er-doped fiber amplifiers.Then the authors proposed a novel optical structure

i.e.using the conventional EDFA in the first stage to improve NF and ytterbium-erbium co-doped dual-clad fiber pumped by high power multimode laser diode in the second stage to increase the output power.The prototype amplifier with this structure has output power of 30.9 dBm and NF of 5.2 dB.