Ytterbium-doped double-cladding fiber with 3.5 kW output power, fabricated by chelate gas phase deposition technique

A ytterbium-doped double-cladding fiber was successfully fabricated by a chelate gas phase deposited technique. The measurement results of dopant concentration distribution and refractive index of preform indicate that radial and longitudinal homogeneity could be controlled perfectly with this technique. The absorption coefficients of fiber are 0.39 dB/m at 915nm and 1.02 dB/m at 976nm respectively. Using this fiber as the laser amplifier stage, 3592W output power at 1080nm with 72.5% slope efficiency was obtained with end-pump technique, which is close to the test results of Nufern commercial fiber. The results demonstrate that the chelate gas phase deposition technique is a relatively promising technique for high quality gain fiber fabrication. (C) 2016 Optical Society of Americ