Frequency doubling of an efficient continuous wave single-mode Yb-doped fiber laser at 978 nm in a periodically-poled MgO:LiNbO3 waveguide

A single-mode Yb-doped fiber laser producing 2 W CW at 978 nm is demonstrated with a high slope efficiency of 72%. Thanks to its narrow bandwidth, lower than 0.02 nm, and its tunability of 6 nm, it has been efficiently frequency doubled in a periodically poled MgO:LiNbO3 waveguide, leading to a power of 83 mW at 489 nm and an internal conversion efficiency of 26 %.