为了实现单波长输出，提出了一种基于单模石英-掺铒-单模石英结构混合介质光纤干涉仪（HFI）的单波长光纤激光器。基于混合介质光纤波导内的光场干涉原理及光波导理论，分析了HFI的模式干涉理论，研究了HFI内干涉光特性随中间段铒掺杂光纤（EDF）长度以及错位量的变化规律;采用熔融错位法制备HFI，优化了EDF的长度和单模光纤与EDF之间的偏移量。结果表明，最佳EDF长度为15 mm，单模光纤与EDF之间的最佳偏移量为7.9 μm;选择长度为15 mm的EDF HFI作为环形光纤激光器谐振腔的选模器件，可获得较高稳定性的单波长光纤激光器输出。这一结果对该激光器在光纤传感和光纤通信系统的应用是有帮助的。

To achieve single wavelength output, a single wavelength fiber laser based on a single-mode quartz-erbium-doped single-mode quartz hybrid fiber interferometer (HFI) was proposed. Based on the optical field interference principle and optical waveguide theory in hybrid dielectric fiber waveguides, the mode interference theory of HFI was analyzed, and the variation of the interference optical characteristics in HFI with the length and dislocation amount of the intermediate erbium-doped fiber (EDF) was studied. HFI was prepared using a melt dislocation method, which optimized the length of the EDF and the offset between the single-mode fiber and the EDF. The results show that, the optimal EDF length is 15 mm, and the optimal offset between the single-mode fiber and the EDF is 7.9 μm. Selecting an EDF HFI with a length of 15 mm as a mode selector for the resonator of a ring fiber laser can achieve a relatively stable single wavelength fiber laser output. This result is helpful for the application of the laser in optical fiber sensing and communication systems.