Discuss modal dispersion as it relates to single-mode and multimode cables.

Question

What will be an ideal response?

Answer 1

Modal dispersion can be greatly reduced by using fiber cables called single-mode cables. Single-mode cables have a diameter of one to two micrometers. The cladding also affects modal dispersion. If the cladding thickness is kept to within three times the wavelength of the light, modal dispersion is eliminated. Another type of cable that is much larger than single-mode cable is multimode cable. Multimode cable ranges in thickness from about 5 to 1000 micrometers. Multimode cable can cause severe modal dispersion in long lengths of several thousand feet. For short runs, however, it is generally preferred because it is larger in size and easier to work with than single-mode cable. Multimode cable is also less expensive than single-mode cable, and for short runs the modal dispersion generally is negligible.