“…To date, RFLs based on a variety of gain mechanisms including rare-earth ion-doped fiber amplifiers, 16 stimulated Brillouin scattering (SBS), 17 stimulated Raman scattering, 18 , 19 and semiconductor optical amplifiers 20 have been reported. By employing regulating and control technologies combined with different gain mechanisms, performances of the reported RFLs have been well improved in many aspects, especially in their lower threshold, 21 higher output power, 22 wavelength tunability, 23 higher coherence, 24 narrower linewidth, 25 lower noise, 26 and more stabilized output power, 27 which enables a wide range of applications for RFLs in optical measurement, 28 microwave photonics, 29 optical fiber communication, 30 optical fiber sensing, 31 laser imaging, 32 and other fields 30 , 33 . Among the above-mentioned RFLs based on different gain mechanisms, the Brillouin random fiber laser (BRFL) stands out by right of its excellent properties, such as the low threshold in long single-mode fiber (SMF), narrow gain bandwidth (∼30 to 40 MHz in standard SMF), high amplification factor, and inhomogeneous broadening gain spectrum.…”