High-power 885nm end-pumped Nd:YAG laser

In diode pumped Nd:YAG lasers the quantum defect is the most important parameter determining the thermal load of the laser crystal. This can be dramatically reduced by pumping directly into the upper laser level. Therefore a high power end-pumped Nd:YAG laser with direct pumping into the upper laser level will be presented. An 8 bar diode stack with central wavelength of 885 nm and a spectral width of 2.5 nm was used to pump a diffusion bonded Nd:YAG crystal with total length of 62 mm and 5 mm in diameter. With an absorbed pump power of 438 W an output power of 250 W was realized. For further power scaling a multi-segmented laser rod was used and up to 276 W of output power was achieved. Further investigations on thermal load and thermal optical effects will be presented.