提出了一种基于双Sagnac环滤波器的可切换多波长掺铒光纤激光器，该滤波器由基于保偏光纤和少模光纤的Sagnac环并联构成，结构简单，利用其梳状滤波特性，实现了掺铒光纤激光器的多波长输出。采用传输矩阵法详细分析了双Sagnac环的传输特性，进一步搭建了线性腔掺铒光纤激光器，实验中通过调节偏振控制器，改变腔内偏振态，在室温下得到稳定可切换的单、双、三波长激光输出，且激光器输出波长的位置可调。研究结果表明，输出激光波长的边模抑制比大于34 dB，稳定性测量中波长漂移量小于0.05 nm，具有良好的稳定性，可应用于波分复用及全光通信系统等领域。

A switchable multi-wavelength erbium-doped fiber laser based on double Sagnac loop filter was proposed. The parallel double Sagnac loop filter was consisted of polarization-maintaining fiber and few-mode fiber. Its structure was simple. And the multi-wavelength output of erbium-doped fiber laser was realized by the comb filter property. Adoptting transmission matrix method, the characteristics of double Sagnac loop were analyzed in detail. When using the double Sagnac comb filter in linear cavity laser system, a switchable multi-wavelength fiber laser with stable single-, dual-, and triple-wavelength outputs can be obtained at room temperature by adjusting the polarization controllers and changing the polarization state in the cavity. At the same time the lasing wavelength locations also can be switched. The results show that the side mode suppression ratio (SMSR) of the output wavelength is more than 34 dB. In the test of the stability, the maximum wavelength shift of output wavelength is less than 0.05 nm, which has stable output and can be applied in fields such as wavelength division multiplexing and all-optical communication systems.