Abstract

Mid-infrared lasers operating in the 2-5 µm region have been attracting a great deal of interest due to their usage in many diverse fields such as range finding [1], remote sensing [2], and medicine [3]. In the case of surgical intervention, efficient energy transfer between the laser and the tissue is required, therefore high absorption in the tissue is necessary. Strong absorption of water at 2.94 µm [4] then sets the laser wavelength, especially for surgery applications. The most commonly used lasers are 2.94-µm Er³⁺:YAG lasers, producing ~3-4 J/pulse energies with µs pulse durations. As an attractive alternative, Dy³⁺ ion possesses broad emission bands centered around 2.9 µm, but usually suffers from low photon quantum efficiency (λ_p/λ_L). Alternatively, co-doping with ions such as ytterbium (Yb³⁺) [5] and thulium (Tm³⁺) [6] can potentially provide a direct diode pumping possibility. In this study, we investigated the potential energy transfer mechanisms between Tm³⁺ and Dy³⁺ ions for Tm³⁺ in-band pumping using several concentration combinations in KY₃F₁₀ crystals.

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