Resonantly Pumped Tm,Ho:BaF₂ and Tm,Ho:SrF₂ Laser Systems Emitting in Atmospheric Window Around 2.04 μm

Holmium lasers represent an effective and powerful source of laser radiation in the atmospheric windows in the 2 μm region and they are very attractive due to their possible applications in atmospheric remote sensing [1]. Fluorite-type crystals, such as calcium, strontium and barium fluorides, feature long radiative lifetimes of Ho<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> multiplets and weak non-radiative relaxation due to their low phonon energies. In addition, these crystals benefit from rare-earth ion clustering leading to broadband emission properties. Tm-codoping helps to simplify pumping of Ho-based lasers and improves their robustness. In our previous works, we demonstrated efficient excitation of H03+ ions in CaF2 by diode pumping of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Tm}^{3+}$</tex> ions (at 785 nm or 1.7 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{m}$</tex>) [2], [3]. In this study we firstly present promising results obtained with resonant diode pumping of new Tm, Ho- doped strontium and barium fluorites.