What is Optical Fiber?

It is the communication technology that works by sending signals through the thin strands of glass fiber (and sometimes plastic fiber). It all started about 30 years ago in research and development labs (Corning, Bell Labs, ITT UK etc.) and was first installed in Chicago, Illinois, USA, in 1976. In the early 1980s, fiber optic networks connected the main coastal cities.

In the mid-1980s, fiber was replacing all telecommunications, copper, microwave and satellite links. In the 1990s, CATV discovered fiber and used it to increase the reliability of its networks, a serious problem. Along the way, they discovered that they could offer telephone and Internet services on the same fiber and significantly expanded their markets.

Computers and LANs started using fiber in the same period as telecommunications companies. Industrial bonds were the first, since the immunity to noise of the fiber and its ability to distance make it ideal for the factory floor. Mainframe storage networks followed, the predecessors of today's fiber SANs (storage area networks).

Other applications have also been developed: data buses for planes, ships and cars, CCTV cameras for security and even connections to consumer digital stereos!

Today, optical fiber is the dominant medium or logical option for all communication systems.

What is Fiber Optics?

Whenever you read an article or talk to someone about fiber optics, you need to know the writer's point of view. Optical fiber, as you see, is not the same. The writer is discussing "outside the factory" optical fiber, used in telephone or CATV networks. Or is the fiber optic "installations" article on buildings and campuses?

Like "wire", which can mean many different things - power, security, HVAC, CCTV, LAN or telephone - optical fibers are not all the same. And that can be a big source of confusion for the beginner. Check here for the fiber optic contractor jobs

Let's define our terms.

Outside Plant (OSP)

Telephone companies, CATVs and the Internet use many optical fibers, most of which are located outside buildings. It hangs on poles, is buried underground, pulled by a conduit or even submerged in water. Most travel relatively long distances, from a few thousand feet to hundreds of kilometers.

The installations of external systems are all in single-mode fiber (we will define the types of fiber in the next chapter) and cables generally have a very large number of fibers, up to 288 fibers. The cable designs are optimized to resist moisture and damage to rodents. Installation requires special pullers or plows and even trailers to transport giant cable reels.

Long distances mean that the cables are connected to each other, since the cables do not exceed about 4 km (2.5 miles) and most splices occur by fusion joining. The connectors (SC, ST or FC styles) on the factory-made braids are connected to the end of the cable. After installation, each fiber and splice is tested with an OTDR.

If it looks like a lot of money, you're right! The installer usually has a temperature controlled van or trailer for intersections and / or dump trucks. Investment in fusion joints and OTDRs can reach over $ 100,000.

Contractors who work outside the factory are few and far between. Most of the external telephone installations are carried out by the telecommunications company itself, while a limited number of large specialized installers manage CATV.

Installation wiring

On the other hand, the wiring of the installation - installed in a building or on a campus - involves short lengths, rarely exceeding a few hundred feet, with normally 2 to 48 fibers per cable. The fiber is mainly multimode, except the experienced user who installs the hybrid cable with multimode and singlemode fibers.

The change is largely unknown in local applications. Cables between buildings can be purchased with double coatings, PE for the external protection of plants on PVC for applications in buildings that require fire retardant coatings, so that cables can circulate continuously between buildings. Power connectors generally lose less than joints and connection panels offer more flexibility for movement, additions and modifications.

Most connectors are of the ST type, with some SC here and there. Termination occurs by installing connectors directly on the ends of the fibers, mainly using adhesive technology or, occasionally, some other variety of termination methods. The test is performed from a source and a meter, but each installer must have a torch-type tracker to check the continuity and connection of the fiber.

Unlike the external plant technician, the room wiring (which usually installs the power cable and Cat 5 also for LANs!) Probably has an investment of less than $ 2,000 in test tools and equipment.

There are thousands of cable installers doing fiber optic work. They found that this is not "rocket science" and their small initial investment in training, tools and test equipment is quickly compensated.