Low loss fluoride fibre by reduced pressure casting

A major cause of loss in fluoride fibres has been extrinsic scatter from bubbles trapped in preforms during casting. A new reduced pressure casting (RPC) technique has been developed to eliminate bubbles, and the minimum fibre loss has been reduced to 0.65 ± 0.25 dB/km at 2.59 μm, measured over a 110 m length of fibre.