Bandwidth-tunable and mode-switchable multi-wavelength random fiber laser

The invention discloses a bandwidth-tunable and mode-switchable multi-wavelength random fiber laser, which is a bandwidth-tunable and mode-switchable multi-wavelength random fiber laser based on mixed gains of an erbium-doped fiber, stimulated Raman scattering and stimulated Brillouin scattering. Rayleigh scattering is amplified by stimulated Raman scattering by adjusting the output power of the pump light source, and multi-wavelength random distribution feedback is enhanced, so that flat wide-spectrum multi-wavelength random laser output is obtained; by adjusting the output wavelength and the output power of the tunable narrow linewidth laser source, the wide-spectrum multi-wavelength random laser is dynamically filtered. The all-fiber laser has the advantages of being simple in structure, high in reliability, low in manufacturing cost, low in threshold power, stable in output, all-fiber and the like, has the unique characteristics of being diversified in gain type, flat in spectrum, large in spectral bandwi