Over the past decades, multi-wavelength fiber lasers have aroused great interest due to their potential applications in wavelength division multiplexing (WDM) systems and fiber optic
sensing networks, coherent optical communication and testing, optical storage and other fields [1–5]. At room temperature, multi-wavelength fiber lasers can be achieved by using nonlinear optical effects such as Stimulated Brillouin scattering (SBS) [6], four-wave mixing (FWM) [7] and nonlinear polarization rotation (NPR) [8]. The requirements for developing multi-wavelength light sources include spacing tunable multi-wavelength lasing lines and stabilized flattened peak powers. In the reported schemes, additional auxiliary devices are commonly required for the frequency spacing tunable multi-wavelength fiber laser. A tunable Mach–Zehnder interferometer (MZI) [9], chirped-fiber Bragg gratings (CFBG) [10], an array waveguide grating (AWG) [7] have been employed as filters to realize the tunable frequency spacing. Those approaches greatly increase not only the cavity loss but also the cost of the fiber laser.