Chromatic Dispersion Chromatic dispersion is the dispersion of light waves of different wavelengths. Material Dispersion Material dispersion stems from the difference in the refraction index with respect to wavelength. This results in light waves of different wavelengths that travel at different speeds. A wider spectral width results in more material dispersion due to the greater difference in wavelengths in the signal. For standard singlemode fiber, material dispersion is positive for wavelengths above 1300 nm, negative for wavelengths below 1300 nm, and near 0 around 1300nm.
Material dispersion is more significant for single-mode than multimode fibers.
Waveguide Dispersion Waveguide dispersion occurs as optical energy travels at different speeds in the core and in the cladding. This has a greater effect on single-mode than multimode fibers. Waveguide dispersion is negative, relatively small, and relatively constant with respect to wavelength. PMD results from different states of polarization in the optical signal propagating at different speeds. PMD is a problem chiefly in long links with very high bit rates.