Single fiber modules (BiDi) use one fiber for both transmitting and receiving data. They use. 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. ” This technology is foundational to modern digital communication, enabling the high-speed transfer of massive amounts of data over vast distances. Let's break down these terms in simple, clear language with practical examples. While they may look similar from the outside, they differ significantly in core size, transmission behavior, distance capability, bandwidth potential, equipment requirements, and overall cost.