Chromatic dispersion

The spreading of a particular light pulse because of the varying refraction rates of the different colored wavelengths. Different wavelengths travel along an optical medium at different speeds. Wavelengths reach the end of the medium at different times, causing the light pulse to spread. This chromatic dispersion is expressed in picoseconds per kilometer per nanometer (of bandwidth). It is the sum of material and waveguide dispersions. See also waveguide dispersion, material dispersion.