Er:KY 3 F 10 laser at 280 µm

We report on the mid-infrared laser operation of a cubic 15 at.% E r 3 + : K Y 3 F 10 crystal. In the quasi-continuous-wave regime, the peak power reaches 255 mW at 2.80 µm (the 4 I 11 / 2 → 4 I 13 / 2 transition) with a slope efficiency of 10.9% and a laser threshold of 58 mW. Two pumping schemes (to the 4 I 11 / 2 and 4 I 9 / 2 states) are compared. The emission properties of the E r 3 + ions in K Y 3 F 10 are studied, indicating high stimulated-emission cross-section of 0.57 × 10 − 20 c m 2 at 2.80 µm, a large gain bandwidth of 40 nm, and a long 4 I 11 / 2 state lifetime of 4.64 ms.