Water-cooled Yb : YAG disk laser pumped by a stacked diode array

A major problem using laser diodes for longitudinal pumping of solid-state lasers is the poor beam quality and the nonsymmetric beam profile of the di odes, as the astigmatic beam emitted from the array of diodes exhibits a li mited focusability in the direction of the slow axis of the diodes. To over come this problem an optic which turns the astigmatic beam of a stacked dio de array into a radially symmetric (stigmatic) beam has been designed. This symmetric beam is then focused into an axially water-cooled disk laser to serve as a longitudinal pump source. Up to now, different laser crystals ha ve been investigated as a laser source. Using Yb:YAG an output power of 60 W in qcw operation has been realized, whereas Nd : YVO4 delivers a qcw powe r of 113 W. The optical to optical efficiencies are 18 and 32.3%, respectiv ely.