Thermal physics of the BaEr2F8:Tm:Ho active medium

A study was made of the evolution of heat in BaEr₂F₈:[Tm(5%) + Ho(1%)] as a function of the electrical pump energy. The evolution of heat was resolved into components associated with the delivery of the absorbed energy to the active level and with the dark relaxation of the population of this level. An original method was used to determine the efficiency of utilization of the electrical energy (delivered to the pump lamps) in the active medium and the maximum value of the differential efficiency. Participation of cross-relaxation processes in the conversion of the absorbed energy reduced the heat evolution in the BaEr₂F₈:Tm:Ho medium by a factor exceeding 3.