Single mode fiber, due to its small core diameter, allows light to propagate in only one mode within the fiber. This characteristic results in extremely low intermodal dispersion, making optical signal transmission more stable and maintaining high quality over long distances. The group velocity associated with the fundamental mode is frequency dependent. Intermodal dispersion (also called modal dispersion) is the phenomenon that the group velocity of light propagating in a multimode fiber (or other waveguide) depends not only on the optical frequency (→ chromatic dispersion) but also on the propagation mode involved.