Tailoring zero chromatic dispersion into the 1.5-1.6 μm low-loss spectral region of single-mode fibres

We have designed and fabricated single-mode silica fibres that have zero chromatic dispersion within the 1.5–1.6 μm low-loss spectral region by controlling their waveguide dispersion and dopant-dependent material dispersion. These fibres have small core diameters and large core-cladding refractive-index differences, Δn = 0.018, corresponding to a 13 mole % GeO2 dopant concentration in the core. The zero-dispersion wavelength was shifted from λ0 = 1.375 μ to λ0 = 1.54 μ by decreasing the fibre core diameter from 7 μm to 4.8 μm. This ability to tailor the minimum dispersion wavelength to the ultra-low-loss region near 1.55 μm is important for designing single-mode fibres for very long distance and very high capacity optical transmission.