Diode-pumped 1028 nm Ytterbium-doped fiber laser with near 90% slope efficiency

Highly efficient laser action from an Ytterbium-doped fiber (YDF) is demonstrated using a fiber Bragg grating (FBG) in conjunction with a 4% Fresnel reflection at room temperature. The YDF used is drawn from Yb(2)O(3)-doped preform, fabricated through deposition of porous layer of composition SiO(2)-GeO(2) by the MCVD process in conjunction with a solution doping technique. The fabricated YDF has a core composition of 0.2 wt % of Yb(2)O(3), 1.8 wt % of Al(2)O(3) and 23 wt % of GeO(2) with a pump absorption of 9.0 dB/m. The fiber laser operates at wavelength of 1028 nm with a slope efficiency of 88% with respect to the launched 976 nm pump power using the YDF length of 7 m