(from the article `telecommunications media`) Other important causes of signal distortion in optical fibres are material dispersion and waveguide dispersion. Material dispersion is a phenomenon ...
that dispersion in a signal attributable to the dependence of the phase and group velocities on wavelength due to the geometric properties of the fibre NOTE - For optical fibres the dependence is on the ratio (a/?), where a is core radius and ? is wavelength.
Dispersion arising from the dependence of the speed of light on wavelength due to the geometrical properties of the fibre.