Geometrical transformation of linear diode-laser arrays for longitudinal pumping of solid-state lasers

A 200-stripe linear diode-laser array is geometrically transformed into a two-dimensional, symmetric virtual source with symmetric divergence to end pump a Nd:YAG laser. The geometrical transformation is performed by two planes of diffractive optical elements separated by a 2.6-cm gap. Discounting optical losses, a TEM/sub 00/ mode slope efficiency of 56% is demonstrated. Methods of increasing the throughput efficiency of the diffractive elements (currently approximately 50% per element,) are explored. A theoretical model for estimating the maximum useful pump array size in longitudinally pumped rod and fiber lasers shows that this pump geometry is close to optimum.<
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