Rmm-Temperature Law Pumped 2.m Holmium Lasers.

processes in YbLiF,:Ho(0.4%) and YbLiF4:Ho(0.4%),Tm(lO~h) crystals and in the series of crystals an KYb(WOS*:Tm,Ho(O.4%) with the thulium wnccmtration 0.5; IO; and 20% The population kinetics of the 511 holmium level was studied under the 1.047 pm Q-switched YLFNd laser pumping, the lasing energy was 100 ml, pulse length 100 sec. The pumping power density was varied by light filters within one order of magnitude. It is shown that in the YbLiF4:Ho and YbLiF4:Hn.Tm crystals the pumping rate of the SI, hnlmium level increases because of the up-wnvmion and energy transfer processes due to wupling of Yb, Tm, and Ho ions. With an increasing pump power density, the population of the '17 holmium level increases greatly, however, in the presence of Tm ions, the efficient up-conversion from the IIi level takes place which decreases greatly its population and thus increases the threshold pump energy With an YbLiF~:Ho(OA%) laser rod we have obtained lasing at 2.06 pm with the total eiliciency 4.W.. the slope cffciency I I%, and the threshold energy was E-h -1% mJ. In the Tm-doped crysfals. the enerm thdnld is E,*=] 100 mJ due to the upconversion from '1, holmium level. Unlike the fluoride matnx, in the KYb(WO+:Tm.Ho crystals the up-mnvmion processes are less eflicient than in YbLiF1:Ho: the Tm-Tm and Tm-Ho coupling increases the pumping rate of the 'I, level, but its decay rate changes slowly. the life time of the '17 level deaeasff less than three times with an increme in the Tm concentration from 0 to 20% The optimal population is obtained in crystals with the 10% Tm concentration. This means that in this case the up-conversion is too weak. In the KYb(WO+)~:Tm.Ho(0.4%) crystals, lasing was obtained in all the Tmdoped (0.5, IO n 20%) crystals. In the Tm-less lasa rod stimulated emission was not achieved. In the crystal with Yh of Tm. the threshold is Elh=1200 ml. Most eficient laser action was observed in the crystal with loo/. of Tm, the pumping threshold being - 150 d, total eflidency 6% and slope &ciency 9.7%. Thus, the generation studies have shod a god agreement with the spactroscopic scheme of coupling of .doping ions in the fluoride and potassiumytterbium-tungstate crystals. 'Re work wns supported b.v Rursian Foundution for Bmir Rexarrhes. Granr Nu. 97-02-16439 CWF21