Emission Properties of Tm³⁺-Ln³⁺ (Ho³⁺, Tb³⁺, Eu³⁺) Co-Doped Tellurite Glasses by Energy Transfer

Abstract

Generally, it is difficult for 1.4μm band amplification to form population inversion between the initial ³H₄ and the terminal ³F₄ levels in Tm³⁺, because lifetime of the initial level is shorter than that of the terminal level. Accordingly emission properties and lifetimes of tellurite glasses co-doped with Tm³⁺ and various rare earth ions (Ho³⁺, Tb³⁺ and Eu³⁺) were investigated in order to improve the population inversion by co-doping method. These co-doped ions depopulated the terminal level rapidly by energy transfer from the terminal level to the co-doped ion. Especially, for the initial level, Ho³⁺ did not affect the population of the initial level because Ho³⁺ cannot easily cause cross-relaxation. Ho³⁺ had the largest effect on lifetime of the terminal level without decreasing the population of the initial level. Ho³⁺ showed the best performance among three investigated rare earth ions as a co-doped ion.