研究了一种新型的光纤环形镜(FLM)的原理和特性,这种FLM是由耦合比对波长变化的耦合器即过耦合器和偏振控制器(PC)构成,改变PC的状态,可以调节环的反射谱位置和深度。与高双折射光纤环形镜构成线型谐振腔,调整光纤环内PC的状态可以改变环对不同波长的反射率,控制腔内的增益从而输出可变波长的激光。实验得到输出波长在1564~1592 nm范围内,波长调谐范围为28 nm,3 dB线宽小于0.2 nm,边模抑制比(SMSR)大于40 dB的稳定激光输出。 The principle and characteristics of a new type of fiber loop mirror (FLM) are studied. The FLM is composed of couplers whose coupling ratio changes with wavelength, that is, overcoupler and polarization controller (PC). By changing the state of PC, The reflection spectrum position and depth of the ring. And the high birefringence fiber ring mirror linear resonant cavity, adjust the status of the PC within the fiber ring can change the ring of different wavelengths of reflectivity, control the gain within the cavity to output variable wavelength laser. The experimental results show that the output of a stable laser with an output wavelength of 1564-1592 nm, a wavelength tuning range of 28 nm, a 3 dB linewidth of less than 0.2 nm, and an edge mode suppression ratio (SMSR) greater than 40 dB is obtained.