High-inversion densities in Nd:YAG-upconversion and bleaching

摘要

We report on the investigation of upconversion in Nd:YAG and itsnimplications for intensely pumped devices. Analysis of lifetimenmeasurements and the performance of a 1 at.% Nd-doped YAG amplifier givenan Auger upconversion rate of 7×103 s-1.nThis is significantly smaller than previously reported, but modeling ofnthe performance of Nd:YAG devices with high-inversion densities showsnthat even this rate can still seriously degrade the small-signal gainnand significantly increase the thermal load. The variation ofncross-relaxation and upconversion rates with doping level is alsondescribed. Finally, it is found that the effect of bleaching of thenNd:YAG absorption can lead to a reduced spatial overlap between thensignal and inversion profiles and thus can also significantly reduce thengain