High-power single-mode fiber laser system

The invention provides a high-power single-mode fiber laser system, which comprises a seed laser and a main amplifier, seed laser output by the seed laser is injected into the main amplifier for power amplification and then is output, and the main amplifier comprises a gain fiber; the gain fiber comprises 2N + 1 sections, N is greater than or equal to 1, odd sections, namely a first section, a third section,..., and a (2N + 1) th section, are sections with uniform fiber cores and claddings, and the diameters of the fiber cores and the claddings of the first section, the third section,..., and the (2N + 1) th section are gradually increased; the even-number sections, namely the second section, the fourth section,..., and the 2Nth section, are conical transition sections; seed laser is injected from the small-core-diameter end of the gain optical fiber, a bending loss mechanism is introduced to achieve effective suppression of the TMI effect, signal laser is output at the maximum-core-diameter end of the gain o