FIBER OPTIC BASICSPART 1

On-Line Course

FIBER OPTIC BASICSBefore starting, you should have a copy of the 2008 NEC and have downloaded a copy of the fiber handout PDF from LERC. Some

of the answers asked in this course are found only in those documents.

Fiber Optics

Transmitting communications signals over hair thin strands of glass or plastic is not a "new" technology.

The concept is over a century old but has been used commercially for only about 25 years

The first long distance networks were operational in the early 1980s. By 1985, most of today's basic technology was developed and being installed in the fiber optic networks that now handle virtually all long distance telecommunications.

The first commercial fiber optic installation was in for telephone signals in Chicago, installed in 1976.

Applications include – Telecom - telephones and the Internet– LANs - local area networks– CATV - for video, voice and Internet

connections– Utilities - management of power grid– Security - CCTV and intrusion

sensors– Military - everywhere!

These are but a few of the applications of fiber optics, as we concentrate on communications. Fiber optics are also used for

lighting, signs, sensors and visual inspection (medicine and non-destructive testing).

Why use Fiber Optics? The biggest advantage of optical fiber is the fact it

can transport more information longer distances in less time than any other communications medium. In addition, it is unaffected by the interference of electromagnetic radiation which makes it possible to transmit information and data with less noise and less error. Fiber is lighter than copper wires which makes it popular for aircraft and automotive applications. These advantages open up the doors for many other advantages that make the use of optical fiber the most logical choice in data transmission.

Fiber Optic Myths!!!1. Light from the fiber will harm eyes2. Fiber is extremely hard to work with3. Fiber is fragile4. Fiber is expensive5. You need expensive installation and

test equipment

Fiber Optic Myths!!!1. Fiber optic sources, especially LEDs used

with multimode fiber are generally too low in power to cause any eye damage. Some laser transmitters used in telecom and CATV systems have very high power and they could be harmful, so better safe than sorry. NEVER LOOK INTO THE END OF THE FIBER ANYWAY. And it’s infrared light, so you eye can’t see it under any circumstances!

2. Fiber is no harder to install, splice or terminate than copper wire. It takes some training, practice and patience, but so does copper.

Fiber Optic Myths!!!3. Fragile? What is a fiberglass boat reinforced

with?4. Today, fiber is cheaper than kite string or

fishing line. Connectors are getting cheaper too. And all the while, copper components are getting more expensive as they try to keep up with fiber for new high bitrate networks.

5. And a good fiber test set is under $1000 while a copper tester will run $6000 or more.

Fiber Optic ApplicationsAbout the only place fiber has not become the

dominant cable is desktop connections for LANs. Priced to just replace copper, it is more expensive, but using a centralized fiber architecture, fiber allows the removal of electronics from the telecom room and ends up being less expensive!

Fiber is already used in:– > 90% of all long distance telephony– > 50% of all local telephony– Most CATV networks– Most LAN backbones– Many video surveillance links

Fiber Optic Applications

Singlemode fiber has a bandwidth of greater than a terahertz. Systems today carry up to 64 channels of 10 gigabit signals - each at a unique wavelength.

Fiber is the least expensive, most reliable method for high speed and/or long distance communications

While we already transmit signals at GB/s speeds, we have only started to utilize the potential bandwidth of fiber

Fiber Optic Applications

“Fiber optics” is not all the same. “Outside plant” refers to fiber optics as used outdoors in telephone networks or CATV. “Premises” fiber optics is used in buildings and on campuses.

Outside Plant: Telephone companies, CATV and the Internet all use lots of fiber optics, most of which is outside buildings. It hangs from poles, is buried underground, pulled through conduit or is even submerged underwater. Most of it goes relatively long distances, from a few thousand feet to hundreds of miles, over what we call “singlemode” fiber.

Fiber Optic Applications

Premises Cabling: By contrast, premises cabling involves cables installed in buildings for LANs or security systems. It involves short lengths, rarely longer than a few hundred to two thousand feet, of mostly “multimode” fiber.

Both these applications are unique in the components they use, the installation methods and the testing procedures, but they share many of the basic principles we learn in this course.