Extruded tellurite glass and fibers with low OH content for mid-infrared applications

Reducing the hydroxyl group content in tellurite glass fibers is essential to exploit the intrinsic mid-infrared transparency of tellurite glass for optical fiber devices. We report the first extruded tellurite glass fibers with low hydroxyl (OH) group content using dry atmosphere for glass melting. For small melt volumes, optimized melting conditions have been identified that enable the absorption at the OH peak at 3.3 μm to be reduced by more than an order of magnitude compared with glasses melted in open air. Annealing and dehydration of tellurite glass in open air was found not to change the OH content. The loss of optical fibers drawn from extruded rods was reduced from ~20 dB/m at 2.0 μm for glass melted in open air to 0.8 dB/m for glass melted in dry atmosphere.