A PROCESS FOR FABRICATION OF YTTERBIUM DOPED OPTICAL FIBER

摘要

The present invention provides a process for fabrication of ytterbium (Yb) doped optical fiber through vapor phase doping technique. The method comprises deposition of Al2O3 and Yb2O3 in vapor phase simultaneously in combination with silica during formation of sintered core layer. This is followed by collapsing at a high temperature in stepwise manner to produce the preform and drawing of fibers of appropriate dimension. The process parameters have been optimized in such a way that Al and Yb-chelate compounds can be transported to the reaction zone without decomposition and condensation of precursor materials. Thus variations of dopants concentration along the length of the preform have been minimized to <1% and good repeatability of the process has also been achieved. The resulting fibers also have smooth core-clad boundary devoid of any star-like defect. The process can be reliably adopted for fabrication of large core Yb doped optical fibers. The fibers also show low loss, negligible center dip and good optical properties suitable for their application as fiber lasers.