Source of optical loss in tellurite glass fibers

Non-silica-based optical fibers generally suffer from high optical loss and low strength, whereas they have other optical properties superior to that of silica for certain device applications. Tellurite glasses offer one of the best compromises among optical, mechanical, and processing properties. The goal of this study was to achieve low loss tellurite fibers for active and non-linear applications. In this paper, single mode tellurite fibers doped with KNbO3 were made with losses varying from 1.3 to 6 dB/m. The sources of loss were striation, dust particles, and bubbles. The decrease of striation was observed by employing lower pouring temperature, and the increase of fiber strength was achieved by hydrochloric acid etching of preform.