Efficient cw operation of the Er3+:GSGG 4I11/2→4I13/2 laser transition at 2.8 µm is demonstrated at room temperature. The 4I11/2 upper laser state is directly pumped at 0.97 µm. The slope efficiency for the 2.8-µm laser is 36%, indicating a greater than unity quantum efficiency. This excess efficiency results from the recycling of population through upconversion out of the lower laser state.
© 1992 Optical Society of America
R. C. Stoneman and L. Esterowitz, "Efficient resonantly pumped 2.8-µm Er3+:GSGG laser," Opt. Lett. 17, 816-818 (1992)