Preparation of ytterbium-doped silica optical fiber using MCVD process with chelate precursor

Ytterbium-doped silica optical fibers were fabricated using a modified chemical vapor deposition process with chelate precursor. The typical core diameters of the preforms made by the chelate doping method are 5.79mm, and the useful length of the preforms is about 900mm, twice the length of the preforms by the solution doping method. The Ytterbium-doped fiber with octagonal inner cladding shape drawn in a double clad configuration has a background loss of 15dB/km at 1200nm. The Ytterbium ion concentration in the fiber core is up to 0.709wt% and a slope efficiency of 81.9% can be generated when pumped with 915nm laser.