Method and system for improving stimulated Brillouin scattering threshold value of fiber laser

The invention provides a method and a system for improving a stimulated Brillouin scattering threshold value of a fiber laser. According to the method, a polarization control system regulates laser emitted by a laser into first polarized light and second polarized light which are orthogonal to each other according to a preset time interval, so that the first polarized light and the second polarized light are transmitted alternately, and polarization states of the polarized light and backward Stokes light are ensured to be orthogonal to each other so as to reduce stimulated Brillouin scattering gain. Therefore, the threshold value of stimulated Brillouin scattering of the fiber laser is improved. The first polarized light and the second polarized light which are mutually orthogonal are alternately transmitted, the first backward Stokes light and the second polarized light which are generated by the first polarized light do not generate SBS gain, and the second backward Stokes light and the first polarized ligh