Optimised structure for preparing long ultra-low-loss single-mode fibres

Abstract

An optimised structure has been evolved for producing long lengths of ultra-low-loss single-mode fibre. Attenuation figures of 0.6 dB/km at 1.3 μm and 0.34 dB/km at 1.6 μm have been achieved in fibres up to 17.1 km in length. The absorption due to OH impurity has been reduced to <3 dB/km at 1.39 μm.