The effect of cladding geometry on the absorption efficiency of double-clad fiber lasers

In the present work, the inner cladding geometries of a typical double-clad fiber laser are studied and numerically simulated for different cladding shapes to obtain the maximum absorption efficiency for the pump beam. This is performed by using the ray tracing approach and dislocating the fiber core from the center to impose the asymmetry on the investigated geometries. The high absorption efficiency of ~94.5% was obtained for the optimized offset D-shaped double-clad fiber. The hexagonal shape is proposed as a new geometry for the inner cladding to attain higher absorption efficiency. It was found that the absorption efficiency of ~68% for a symmetrical hexagonal can be improved to ~95% for an asymmetrized hexagonal-shaped double-clad fiber laser. Eventually the genetic algorithm was used to enhance the performance of the investigated geometries. This resulted in the further increasing of pump beam absorption efficiency of 99.5% in the genetic algorithm optimized asymmetrized hexagonal shape.

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Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę.