Flattop beam output from high power fiber combiner

This paper studies the method of using a high-power fiber combiner to form a Gaussian beam into a flat-top beam, and divides the factors that affect the shaping effect of the flat-top beam. The theoretical analysis model of the fiber power combiner is established based on the waveguide theory, and the excitation characteristics of the fiber mode in the output fiber are analyzed. Based on the beam propagation method, the propagation and superposition characteristics of the highorder modes excited in the fiber combiner are simulated, and the flat-top beam synthesis method is studied. According to the simulation model, a high-power fiber combiner was made, and a high-power laser beam combining experiment was carried out. Finally, a flat-top beam with a beam quality of 10 and an output power of 20kW is obtained. During the experiment, we also found that the uniformity of the flat-top beam increases as the output power of the fiber laser increases.