Laser apparatus and processing apparatus

Compared with the optical fiber laser for outputting laser light, an optical fiber located on the output side the final stage of the optical fiber laser, wherein the laser core diameter is large, the numerical aperture is larger than the same or, where the optical fiber laser output the laser device comprising propagating light output, and processes the optical fiber is a multimode optical fiber, the. Preferably, the optical fiber laser is designed to output a laser beam of the fundamental mode, the optical fiber located on the output side the final stage of the optical fiber laser, the Raman scattered light at the light output end of the process optical fiber having the total value and the total value and the ratio abruptly larger boundary value less become the length of the power of the laser beam power.