Two microns is a desirable wavelength for many medical applications because of its good tissue interaction and excellent transmission through silica fibers. High repetition rate, required in most of the cases, is difficult to achieve in Tm;Cr:YAG because of the quasi 3-level nature of this transition. This paper discusses possibilities of improvement through optimization of doping concentration.
"2.014-micron Cr;Tm:YAG: optimization of doping concentration for flash lamp operation", Proc. SPIE 1410, Solid State Lasers II, (1 July 1991); doi: 10.1117/12.43594; https://doi.org/10.1117/12.43594