Upconversion versus Pr-deactivation for efficient 3 mu m laser operation in Er

Erbium-doped BaY/sub 2/F/sub 8/ is evaluated as a potential material for a laser diode pumped 3- mu m laser. It is shown that the metastable Er/sup 4/I/sub 13/2/ level is efficiently quenched by the addition of a small amount of Pr, while still leaving the /sup 4/I/sub 11/2/ lifetime fairly long. Measurement of the /sup 4/I/sub 11/2/ and /sup 4/I/sub 13/2/ lifetimes in Er, Pr:BaY/sub 2/F/sub 8/ for 1-100% Er with 0.1-1% Pr show that the /sup 4/I/sub 13/2/ lifetime can be up to 10 times shorter than /sup 4/I/sub 11/2/. To compare this with upconversion type operation of this laser, the authors measured the upconversion coefficients alpha for 5, 10, 20, 50, and 100% Er:BaY/sub 2/F/sub 8/ and compared these to previous measurements for LiYF/sub 4/. These show a similar concentration dependence in both hosts, although BaY/sub 2/F/sub 8/ appears to have a slightly higher ratio of alpha /sub 13/2/ to alpha /sub 11/2/. Laser performance under argon and diode pumping are presented to compare upconversion operation in BaY/sub 2/F/sub 8/ and LiYF/sub 4/, and quasi-4-level operation in Er, Pr:LiYF/sub 4/ laser.<
>