Continuous-wave broadly tunable high-power Cr:CdS laser

We report spectroscopic characteristics and laser properties of the mid-infrared active laser medium Cr²⁺:CdS. Temperature-dependent absorption, luminescence and lifetime measurements of the ⁵E exited state allow determination of peak emission cross section value of 1.35 × 10^-18 cm² in σ-polarization at room temperature. Lifetime values vary from 7.6 µs at 8 K to 0.48 µs at 320 K, corresponding to 22 % quantum yield at 285 K. Under Tm-fiber laser pumping, the continuous-wave output reached 1.8 W at 2.5 μm with 35.5 % slope efficiency. With a single CaF₂ prism, the CW Cr²⁺:CdS laser could be tuned from 2.240 to 3.285 µm.