Beam transformation of 500W laser diode system

For fiber coupling and end-pumping of solid-state lasers, the astigmatic beam emitted from high power diode lasers has to be transformed into a beam with rotational symmetry. In this paper we present the result of beam transformation of a high power laser diode stack. The transformation optics consists of rotated cylindrical lenses, originally used in generating twisted beams from coherent and partially coherent fields. The astigmatic beam emitted from a 500 W two-dimensional laser diode stack is transformed into a rotationally symmetric beam. The symmetrized beam has equal beam widths, equal beam divergences in x, y-directions and the same waist positions.