17 J Ho-Laser At 2 Microns

In this paper 2 Am laser action of YAG:Cr,Tm,Ho under flashlamp excitation is demonstrated and analyzed. Room temperture laser performance of the Ho3+ 5I7 -> 5I8 transition is made possible this material by an efficient Cr-Tm-Ho pump mechanism. The excellent overlap of the Cr3+ absorption spectrum in YAG with the flashlamp emission spectrum and the efficient downconversion process yield slope efficiencies as high as 4.3 %. In this context concentration limitations of the optically active ions are discussed. The increase of the laser threshold energy with increasing rod temperature is mainly due to thermal occupation of the Stark-levels. A decrease of output energy with increasing repetition rate is due to the same effect.