SENSITIZING EFFECT OF TM3-M EMISSION FROM DY3+-DOPED GE25GA5S70 GLASS( ON 2.9 MU)

Energy transfer mechanisms and the effect of Tm3+ addition on the inte nsity of the Dy3+:2.9 mu m emission from Ge25Ga5S70 glass were investi gated. Intensity of the 2.9 mu m fluorescence from Dy3+ increased with increasing Tm3+ content when the Dy3+ concentration remained constant , which indicates the presence of an efficient energy transfer between Tm3+ and Dy3+. A decrease in the measured lifetimes of the Tm3+:F-3(4 ) level and a wide spectral overlap between the Tm3+:1.8 mu m emission and the absorption of Dy3+:H-6(15/2)-->H-6(11/2) also supported the p roposed energy transfer scheme. Analyses of the emission intensities a nd decay times suggested that a direct energy transfer from the Tm3+:F -3(4) level to Dy3+:H-6(11/2) level occurred after a fast diffusion-li mited migration fo the excitation energy among Tm3+.