Fibre Optics Lines

Fibre optics, or optical fibres, are long, thin strands of carefully drawn glass about the diameter of a human hair. These strands are arranged in bundles called optical cables. We rely on them to transmit light signals over long distances.

At the transmitting source, the light signals are encoded with data the same data you see on the screen of a computer. So, the optical fibre transmits “data” by light to a receiving end, where the light signal is decoded as data. Therefore, fibre optics is actually a transmission medium – a “pipe” to carry signals over long distances at very high speeds.

Fibre optic cables carry light signals in modes. A mode is a path that the light beam follows when traveling down the fibre. There are single mode and multimode fibre cables.

Single mode fibre is the simplest structure. It contains a very thin core, and all signals travel straight down the middle without bouncing off the edges. Single mode fibre optic cables are typically used for CATV, Internet, and telephone applications, where the signals are carried by single mode fibres wrapped into a bundle.

Multimode fibre is the other type of fibre optic cable. It is about 10 times larger than a single mode cable. The light beams can travel though the core by following a variety of different paths, or in multiple different modes. These cable types can only send data over short distances. Therefore, they are used, among other applications, for interconnecting computer networks.

There are four types of multimode fibre optic cables, identified by “OM” (optical multimode). An industry association designated them as OM1, OM2, OM3 and OM4. They are described by ISO/IEC 11801. OM4’s standard was approved by TIA/EIA 492AAAD. Each OM has a minimum Modal Bandwidth requirement.

Simplex fibre optic cable constructions contain a single strand of glass. Most often, simplex fibre is used where only a single transmit and/or receive line is required between devices or when a multiplex data signal is used (bi-directional communication over a single fibre).

A duplex fibre cable consists of two strands of glass or plastic fibre. Typically found in a “zip cord” construction format, this cable is most often used for duplex communication between devices where a separate transmit and receive are required.

Shorter “patch cables” or “fibre jumpers” are used to interconnect various pieces of electronic equipment in a server room, telco closet or data centre.

You may have seen plastic fibres carrying coloured lights in decorative applications. What you may not have seen are the real glass fibre optic cables that are now the foundation of our communication and computer networks. Many thousands of miles of installed fibre optic cable carry many types of information underground, in tunnels, building walls, ceilings, and other places you don’t see. For examples of uses of optical fibre in our daily life include applications such as computer networking, broadcasting, medical scanning, military equipment.