Efficient continuous-wave Tm,Ho:CaF<sub>2</sub> laser at 2.1µm
Kirill Eremeev, Pavel Loiko, Abdelmjid Benayad, Gurvan Brasse, Patrice Camy, Alain Braud
Abstract
We report on the first, to the best of our knowledge, continuous-wave laser operation of a Tm 3+ ,Ho 3+ -codoped calcium fluoride crystal at ∼2.1 µm. Tm,Ho:CaF 2 crystals were grown by the Bridgman method, and their spectroscopic properties were studied. The stimulated-emission cross section for the 5 I 7 → 5 I 8 Ho 3+ transition is 0.72 × 10 −20 cm 2 at 2025 nm, and the thermal equilibrium decay time is 11.0 ms. A 3 at. % Tm, 0.3 at. % Ho:CaF 2 laser generated 737 mW at 2062–2088 nm with a slope efficiency of 28.0% and a laser threshold of 133 mW. Continuous wavelength tuning between 1985 and 2114 nm (tuning range: 129 nm) was demonstrated. The Tm,Ho:CaF 2 crystals are promising for ultrashort pulse generation at ∼2 µm.