A tunable multi-wavelength Tm3 +-doped ring fiber laser based on all-fiber Mach-Zehnder (M-Z)interfer-ometer was designed.The Mach-Zehnder fiber filter consisted of two cascaded 2 ×2 3 dB couplers,and it connected to the ring cavity through a fiber coupler and reflecting filter was realized by a Sagnac fiber mirror.In experiment,a fiber laser at 1 573 nm with a output power of 250 mW was used as pump source,and the pump laser was injected into a segment of 4 m single-mode Tm3 +-doped fiber through a 1 570 /2000 nm wavelength division multiplexer (WDM),and then optical gain at 2 μm band was obtained.A polarization controller (PC)was used for adjusting laser polarization loss in the cavity.By observing tunable multi-wavelength laser around 2 μm band,3 wavelengths were obtained by ad-justing the PC.%设计了一种基于马赫－曾德（M-Z）光纤干涉滤波器的可调谐多波长掺铥环形光纤激光器，M-Z 光纤滤波器由两个3 dB 耦合器级联构成，通过光纤耦合器接入环形腔中，并利用Sagnac 光纤反射镜实现反射式滤波。实验利用一个发射功率为250 mW 的1573 nm 光纤激光器作为泵浦源，通过一个1570／2000 nm 波分复用器（WDM）注入一段4 m 长单模掺铥光纤（TDF）中获得2μm 波段光增益。环形腔内加入偏振控制器（PC）调节腔内损耗，实现了2μm波段可调谐多波长输出，观测到最多3个波长激光。
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