光纤激光器和传统的固体激光器相比,以体积小、光转换效率高、稳定性高等诸多的优点得到了广泛的研究。其中,可用于通讯的掺铒光纤激光器及用于激光加工的掺镱光纤激光器更是受到了人们的重视,在掺铒光纤激光器和掺镱光纤激光器中σ腔的形式十分常见。然而,传统σ腔超短脉冲光纤激光器中非线性光学环形镜的一端输出 Compared with the traditional solid-state lasers, fiber lasers have been extensively studied for their advantages of small size, high light conversion efficiency and high stability. Among them, the erbium-doped fiber laser for communication and the ytterbium-doped fiber laser for laser processing have received more and more attention. The form of σ cavity in erbium-doped fiber laser and ytterbium-doped fiber laser is very common. However, one end of the nonlinear optical loop mirror in the conventional sigma-delta ultrashort pulsed fiber laser