Low-loss single-polarisation fibres

Low-loss single-mode fibres that maintain polarisation well have been fabricated by the standard MCVD method. An extinction ratio of less than −30 dB at 1 km and a loss of 0.8 dB/km at 1.5 μm were achieved by the concentric circular germanosilicate core-clad fibres with the borosilicate elliptical jacket.