Status and prospects of mid IR fibres

Pinnow, Van-Uitert and Goodman (1977-78) independently proposed the use of infra-red transmitting materials in optical fibres with a view to reducing intrinsic losses to less than 10^-2 dB/km. The new materials would replace existing silica based fibres and would be used at longer wavelengths in order to take advantage of the reduced Rayleigh scattering. Some ten years on fluorozirconate glasses have been identified as possible materials, and demonstrated to have intrinsic losses close to those originally forecast. These materials have now been converted into fibre in lengths approaching 1 km and minimum losses have been reported which are now approaching those of silica. Progress in the field will be reviewed and the results of preliminary systems studies presented