3.3 kW high power single mode fiber laser

There were many advantages of high power single mode fiber lasers, such as near-diffraction-limitation beam quality, high power, high electro-optical conversion efficiency and high stability. In this paper, high power continuous-wave single mode fiber laser with master oscillator power amplifier configuration was reported. The fiber laser contained one seed laser and one-stage amplifier. The seed laser was a linear oscillator cavity structure with YDF-20/400 as gain fiber. The power of the seed laser was 200 W with the center wavelength of 1080 nm. One back pumped fiber amplifier with YDF-25/400 as gain fiber was built to boost the average power of the seed laser. The pump laser wavelength was 915 nm. The maximum output power is 3.3 kW at the pump power of 4.3 kW. The optical to optical efficiency of the amplifier was 72.6%. The beam quality at maximum output power was M_x²~1.29, M_y²~1.26. The near-diffraction-limitation beam quality would make this fiber laser become potential source for military defense, industry and medicine.