In recent years, multi-wavelength fiber lasers have attracted much attention due to their wide application in fiber sensing, spectrum analyzers, and system testing. Especially with the development of dense wavelength division multiplexing (DWDM) technology, multi-wavelength fiber lasers As a result, it is simple and easy to connect with optical fibers, and has become an important light source in optical communication systems. There are many ways to achieve stable multi-wavelength fiber lasers at room temperature, and the most critical technology is how to suppress the uniform gain broadening benefits of doped fibers. Multi-wavelength Brillouin fiber laser is a new type of multi-wavelength fiber laser. In 1996, it was proposed by Gregory et al. that the nonlinear gain of SBS in the laser can effectively suppress the uniform widening mechanism of EDF, and realize stable, narrow linewidth, and evenly spaced multi-wavelength output at room temperature through multi-stage SBS cascade. . In recent years, the domestic Shanghai Jiaotong University has made great progress in the research work in this area. In 2005, Song and Zhan et al. proposed a self-excited multi-wavelength Brillouin fiber laser. Utilizing the filtering effect of Sagnac mirror and the dynamic distribution feedback effect of Rayleigh in SMF, self-excited multi-wavelength output is realized without narrow linewidth Brillouin pumping. In 2007, Zhang et al. proposed a tunable self-excited multi-wavelength Brillouin fiber laser wavelength. By adjusting the filtering characteristics of the birefringent Sagnac ring mirror, the wavelength of the multi-wavelength Brillouin fiber laser can be tuned, and the wavelength interval is equal to the Brillouin frequency shift. Using the direct transmission output of the Sagnac ring mirror can also improve the conversion efficiency and output power of the multi-wavelength Brillouin fiber laser. In 2008, Huang et al. reported a multi-wavelength Brillouin fiber laser with an output of about 200 wavelengths and a tuning wavelength of about 45 nm. Si Libin of Nankai University and others reported that a high-power multi-wavelength switchable double-clad fiber laser was pumped by a 25 W 976 nm laser to obtain a multi-wavelength output of 6 W.