Low-dispersion single-mode silica fibre with undoped core and three F-doped claddings

The refractive-index profile of an ideal single-mode silica fibre with undoped core and three F-doped claddings was optimised by calculation to realise two zeros of the chromatic dispersion at 1.30 and 1.55 μm where the spectral loss has its local and absolute minima, respectively. The sensitivity of the chromatic dispersion due to different scale factors for the radial co-ordinate of the refractive-index profile is considered.