Large size core planar waveguide laser with uniform pump absorption

A new, to our knowledge, structure planar waveguide is reported in this paper. By designing the light guide layer, the pump absorption distribution of the planar waveguide in the non-waveguide direction ( x axis) is more uniform. The waveguide core size of the fundamental mode in the waveguide direction ( y axis) can be enlarged to 400 μm by introducing the refractive index matching and mode competition, to increase single-pass gain of the waveguide while ensuring good beam quality in the y -axis direction. Using a plano–concave resonator, 320 W output power is extracted at a pump power of 740 W, leading to an optical–optical efficiency of 43% and a slope efficiency of 48%, and the beam quality factors M 2 are measured to be 1.22 and 7.0 in the guided direction and the unguided direction, respectively. Simulations and experiments show that this planar waveguide can effectively alleviate the problem of uneven pump absorption and has great potential in the development of high-power planar waveguide oscillators and amplifiers.