提出并实验研究了一种2 μm波段全光纤间隔可调双波长光纤激光器.该激光器采用传统的环形腔设计，以最大输出功率33 dBm的1 565 nm光纤激光器为泵浦源，4 m单模掺铥光纤为增益介质，腔内为嵌入多模干涉滤波器的Sagnac环的复合滤波结构.该复合滤波器可实现间隔可调谐，高边模抑制比的双波长激光信号输出.通过泵浦功率的控制和对复合滤波器中偏振控制器的调节，实现双波长3 nm到80 nm间隔可调的激光输出，边模抑制比为60 dB，线宽为0.2 nm，功率稳定度为±1.5 dB/h，双峰能量差小于4 dB.

A dual-wavelength tunable spacing all fiber thulium-doped laser is reported and demonstrated.The conventional ring cavity is used in this fiber laser, 1 565 nm pump source can achieve maximum output power 33 dBm, and a segment of 4m long single mode thulium-doped fiber is gain medium.The filter is a composite structure based on multimode interference effect and Sagnac ring. Through the composite filter, it can radiate tunable spacing and high side mode suppression ratiodual- wavelength laser output. The experimental results suggest that not only dual-wavelength tunable spacing from 3 nm to 80 nm, but also SMSR is 60 dB under the controlling of pump power and polarization controller in composite filter，line-width is 0.2 nm ，power fluctuation is ±1.5 dB/h，bimodal energy difference is less than 4 dBm.