In fiber-optic communication, a single-mode optical fiber, also known as fundamental- or mono-mode, is an optical fiber designed to carry only a single mode of light - the transverse mode. Modes are the possible solutions of the Helmholtz equation for waves, which is obtained by combining. Choosing between single mode and multimode fiber is a common decision when designing, deploying, or upgrading fiber optic networks. Although both carry data through light signals, they differ significantly in transmission mechanism, bandwidth-distance capability, deployment cost, and typical. Multimode fiber cables are the type of fiber cables that transmit data via their core of larger diameters enable an average, single-mode transceiver multiple modes of light to propagate through it. However, this limits the maximum length of transmission links possible due to modal dispersion. These feature a small modal dispersion for vast-distance signal transmission. Although they can do the same job in some instances, the different construction methods make each of them better suited to certain tasks and budgets.