中文摘要：

将正色散值较小的掺铒光纤引入传统的环形腔构成了低阂值的展宽脉冲锁模激光器．通过使用这种掺铒光纤，激光器的锁模阂值大大降低，激光器的自起振泵浦功率仅为90mw，而且在29mw的低泵浦功率时仍然可维持稳定的锁模状态．实验中获得了脉冲宽度为175fs，光谱半高宽为40nm，重复频率为33MHz的锁模脉冲输出．激光器工作稳定，光谱干净光滑．

英文摘要：

A low threshold stretched-pulses mode-locked Erbium-doped fiber ring cavity femtosecond laser with small positive-dispersion Era＋-doped fiber was demonstrated. By introducing the small positive-dispersion fiber, the pulse energy and spectrum width were improved, the sideband of the spectrum was effectively restrained, and the self-starting pump power threshold was only 90 roW. The passive mode-locked continued to a pump power level as low as 29 mW. Self-starting mode-locked pulses with time duration of 175 fs,spectral width of 40 nm and repetition rate of 33 MHz were achieved by using this stretched-pulse configuration.