Tailoring zero chromatic dispersion into the 1.5¿1.6 ¿m 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 ¿m 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, ¿n = 0.018, corresponding to a 13 mole % GeO2 dopant concentration in the core. The zero-dispersion wavelength was shifted from ¿0 = 1.375 ¿ to ¿0 = 1.54 ¿ by decreasing the fibre core diameter from 7 ¿m to 4.8 ¿m. This ability to tailor the minimum dispersion wavelength to the ultra-low-loss region near 1.55 ¿m is important for designing single-mode fibres for very long distance and very high capacity optical transmission.