VAD technology for laser fibers

VAD technology has been proposed for laser fiber fabrication to improve its productivity and reproducibility. Rare-earth ion, Yb3+ has been incorporated with Ce3+ and Al3+ by the conventional solution doping process. In order to obtain a transparent Yb-doped core rod, the pre-sintering and consolidation process for the large volume of silica soot deposited by VAD has been significantly investigated. In addition, 20/4001 mu m Yb-doped fiber with octagonal cladding has been fabricated. The cladding absorption was 0.44dB/m at 915nm, which corresponds to similar to 0.2mol% of Yb concentration and the slope efficiency with respect to absorbed pump power at 976nm was 66.7%.