Fiber laser

The utility model belongs to the technical field of lasers, and discloses an optical fiber laser, which comprises an optical isolator, a beam combiner, a resonant cavity, an optical fiber circulator and an optical fiber output end cap which are sequentially connected, the optical fiber circulator is provided with a first port, a second port and a third port, the resonant cavity is connected with the first port, and the optical fiber output end cap is connected with the second port. The optical fiber output end cap is connected to the second port, the third port is connected to a tail fiber, and one end, not connected with the third port, of the tail fiber is provided with high-refractive-index glue and a heat absorption structure. Through the arrangement of the optical fiber circulator, reflected laser entering from the optical fiber output end cap can only be output from a third port of the optical fiber circulator, the effect of filtering return laser is achieved, the high-refractive-index glue can absorb l