Effect of composition on the thermal properties and spontaneous emission probabilities of Tm3+-doped TeO2-LiCl glass

The effect: of composition on the thermal properties and the spontaneous em ission probabilities of various 0.5 mol% Tm2O3 containing (1 - x)TeO2 + (x) LiCl glasses were investigated using differential thermal analysis (DTA) an d ultraviolet-visible-near-infrared (UV/VIS/NIR) absorption measurements. D TA curves of the samples were obtained in the 23-600 degreesC temperature r ange with a heating rate of 10 degreesC/min. The value of the glass transit ion temperature T-g and the crystallization temperature T-c were found to v ary with the glass composition. Melting was not observed for the glasses co ntaining less than 50 mol% LiCl in this temperature range. However, a melti ng peak was observed at T-m = 401 degreesC for the glasses having higher th an 50 mol% LiCl, which were also found to be moisture-sensitive. Absorption measurements in the UV/VIS/NIR region were used to determine spontaneous e mission probabilities for the 4f-4f transitions of Tm3+ ions. Six absorptio n bands corresponding to the absorption of the (1)G(4), F-3(2), F-3(3), F-3 (4), H-3(5), and H-3(4) levels from the H-3(6) ground level were observed. An integrated absorption cross section of each band, except that of H-3(5) level, was found to vary with the glass composition. The role of the Judd-O felt parameters and therefore the effect of the glass composition on the ra diative transition probabilities for the metastable levels of Tm3+ ions are discussed in detail.