Fiber laser is mainly composed of pump source, coupler, rare earth doped fiber, resonator and other components. The pump source is composed of one or more high-power laser diode arrays. The pump light emitted by the pump source is coupled into the rare earth element doped fiber as the gain medium through a special pump structure. The photons at the pump wavelength are absorbed by the doped fiber medium to form a particle number inversion. The stimulated light wave forms a laser output through the feedback and oscillation of the resonant cavity mirror.