Efficient ∼4 µm emission from Pr/Yb co-doped fluoroindate glass.

/ co-doped fluoroindate () glasses were prepared by using a traditional melt-quenching method in dry atmosphere. Pumped by a 976 or 1570 nm laser diode, efficient emissions at ∼4µ were obtained from the / co-doped glasses, which could be ascribed to the transition → of ions. The relative stimulated emission cross section was calculated to be ∼1.44×10 at 4 µm, which was ∼4.2 times larger than that of transition :→ (3.4×10). In addition, combined with transitions → and → of ions, ultra-broadband emission ranging from 2.7 to 4.2 µm was also obtained. Our results indicate that /: glasses could be used to develop efficient ∼4µ lasers and widely tunable mid-infrared lasers.