Spectroscopic properties and energy transfer parameters of Tm³⁺ ions in gallium lanthanum sulfide glass

Abstract

This work presents the spectroscopic characterization of Tm³⁺ doped gallium lanthanum sulfide (GaLaS) chalcogenide glass through absorption, fluorescence and lifetime measurements of excited ³H₄ and ³F₄ states, and a study of Tm³⁺:Tm³⁺ energy transfer. The cross relaxation ³H₄, ³H₆ → ³F₄, ³F₄ responsible for the pumping of level ³F₄ and the laser transition at 1800 nm (³F₄ → ³H₆), as well as the energy migration ³H₄, ³H₆ → ³H₄, ³H₆ processes are studied in terms of the microscopic parameters of energy transfer C_da and C_dd obtained by the Kushida model of multipolar interactions and by a rate equation treatment of the dynamics of levels ³F₄ and ³H₄. From this treatment it was possible to simulate level ³F₄ temporal evolution curves for different Tm³⁺ concentrations, leading to results that are in excellent agreement with experimental ones. All the samples studied in the work present positive optical gain coefficients for excitation densities higher than 12 kW cm⁻² indicating the potentiality of GaLaS:Tm³⁺ glass as a mid-infrared laser active medium.

Journal of Physics - Condensed Matter (2002) Vol.14(41) pp.9495-9505

doi: 10.1088/0953-8984/14/41/307

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