将正色散值较小的掺铒光纤引入传统的环形腔构成了低阈值的展宽脉冲锁模激光器.通过使用这种掺铒光纤,激光器的锁模阈值大大降低,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. The erbium-doped fiber with a small positive dispersion value is introduced into a conventional annular cavity to form a low-threshold broadening pulsed mode-locked laser, and the laser’s mode-locking threshold is greatly reduced by using this erbium-doped fiber. Only 90mW, and can maintain a stable mode-locked state even at a low pump power of 29mW.The experimental results show that the mode-locked pulse output with a pulse width of 175fs, a half-width of 40nm and a repetition frequency of 33MHz is obtained. Stable, clean and smooth spectrum.