Watt-Level Visible Laser In Double-Clad Pr3+-Doped Fluoride Fiber Pumped By A Gan Diode

We report on a red praseodymium fiber laser delivering 1.07 W at 634.5 nm with a slope efficiency of 20.7% (versus the incident pump), a laser threshold of 0.55 W, and a single-mode output (M-x,y(2) < 1.1) in the quasi-continuous- wave regime. It is based on a 0.6 mol.% Pr3+-doped ZBLAN double-clad fiber with a 5.5 mu m core, a double D-shaped (diameters, 115/125 mu m) inner cladding, and a length of 5.0 m. The fiber is pumped by a multimode 443 nm GaN diode. The laser design is optimized using a numerical model. The proposed concept is suitable for the development of diode-pumped high brightness watt-level visible praseodymium fiber lasers. (C) 2020 Optical Society of America