The experimental results show that,at both room temperature and 77 K,the ytterbium-doped fiber(YDF) exhibits obviously inhomogeneous gain broadening,which results that the lasing line number of the laser increases with the increase of pump power.

In this paper,the properties of Erbium-doped and Ytterbium-doped fibers are introduced and the current researches therein and the trend of the development highlighted,which shows that remarkable progress has been made in their development in China.

High repetition rate femtosecond Yb-doped fiber amplifier;