Fluorescence reabsorption analysis on laser cooling of Tm3+ doped ZrF4 -BaF2 -LaF3 -AlF3 -NaF-PbF2 glass

Abstract

Laser cooling of solid material has become a new developing research area in recent years. Tm3+ doped ZrF4-BaF2-LaF3-AlF3-NaF-PbF2 glass is one of the hot materials in this field. Compared with Yb3+, Tm3+ has better cooling potential. Up to date, one of the main factors restricting the cooling effect is fluorescent reabsorption. In this paper, firstly, using several spectral parameters of Tm3+, the reabsorption effect is calculated by stochastic model which is a semianalytical approach to this problem. The average number of absorption events is obtained. Afterwards, the effect of fluorescence trapping due to total internal reflection is analyzed. The results show that the quantum efficiency will be lowed by 0.5%1% due to reabsorption, that the redshift of the mean fluorescence wavelength is in the range of 210 nm, and that the cooling efficiency and the cooling power decrease. Finally, after discussion, we find that the use of a small size and a long thin geometry will benefit to the fluorescence emission and cooling effect.