Fiber laser, gain fiber, method for manufacturing gain fiber, and beam shaping system

The present invention relates to the laser field, and discloses a fiber laser, a gain fiber, a method for manufacturing the gain fiber, and a beam shaping system used for coupling. The fiber laser comprises a pumping LD, a pumping coupling system and the gain fiber, a first film layer which is highly reflective to pumping light and oscillation light is plated at one end of the gain fiber, and a second film layer which is highly reflective to the pumping light and is anti-reflective to the oscillation light is plated at the other end. One end face of the gain fiber is equipped with a micropore which is anti-reflective to the pumping light, or a micro lens used for inputting the pumping light is arranged at one side surface of the gain fiber. The pumping light emitted by the pumping LD passes the pumping coupling system to enter the gain fiber via the micropore or the micro lens, and is reflected repeatedly, totally and internally in the gain fiber for multiple pumping. The fiber laser possesses the short gain fiber and the low-cost multi-mode LD pumping, enables the coupling efficiency of the pumping micropore and the pumping absorptivity of the gain fiber to be improved and the cost to be reduced, and realizes a high power fiber laser structure of low cost.