Fiber mode conversion is the process of changing a multimode fiber (MMF) into a single mode or vice versa. 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. The. Single mode fiber optic cable is made up of a small diameter glass or plastic core surrounded by cladding, which is a layer of reflective material. This small diameter core, typically around 9 microns in diameter, allows only one mode of light to pass through, resulting in a narrower beam of light. Unlike copper cables, which rely on electrical signals, fiber optics use pulses of light to transmit data—offering unmatched bandwidth, low interference, and long-distance capabilities.