What Is a Multi-Mode Optical Fiber?

A multi-mode optical fiber is a type of wire that is responsible for sending light signals to computers, TVs and telephones. This type of wire carries many different light rays at once, each with a different angle. The wide variety of light angles at the same time means the multi-mode optical fiber can serve many different devices at once; at the same time, it is only effective for short distances, because the light disperses over long distances. Data rates for this optical fiber range from around 10 megabits per second (Mbit/s) to 10 gigabits per second (Gbit/s). If a long-distance wire is required, then a single-mode wire is used instead of a multi-mode one.

When a multi-mode optical fiber cable is used, the fibers are capable of sending out many different light signals at once. Each light signal is used to power a device, such as a TV or a computer’s Internet; many devices can be powered at once, because of the large number of light signals. Each light ray has a different angle as it travels through the cable, so they do not bump into one another. These cables are used over single-mode fiber because simpler hardware is needed to control the light rays and, thus, they are more cost-effective.

While a multi-mode optical fiber is cheaper than a single-mode fiber, it is only effective at supplying power to short distances, around 1,968 feet (600 meters). This is because of the different light rays working at once. If the cable is used for longer distances, the light rays begin either to conflict or disperse, meaning that power is inefficiently transferred or will not reach the target destination.

Depending on the cable type, a multi-mode optical fiber has a moderate to high data transfer rate. On a low level, multi-mode fibers can transfer 10 Mbits/s, while a higher-grade fiber can transfer up to 10 Gbits/s. This is typically enough to serve devices in a business building or college campus, the two most common users of multi-mode fiber cables.

If long distance is required then, instead of a multi-mode optical fiber, a single-mode fiber is used. These fibers have similar data transfer rates, but the light within the fiber acts differently. Instead of sending out many different light signals at once, one signal is sent at a time. This keeps the light from dispersing and signals from conflicting, which allows the light to travel farther.