Introduction to Fiber Optics Presented by: James Carter Sales Engineer – Cox Business.

Introduction to Fiber Optics

Presented by: James CarterSales Engineer – Cox Business

Scope

This presentation is designed to give a generaloverview of fiber optic theory, its construction,the two basic types of fibers, and the benefitsof fiber networks over traditional copper based networks.

Content• Terms• Definition• Quick history• Wavelengths of light• Anatomy of a fiber• Types of fiber• Model of a simple fiber optic link• Benefits over copper-based networks• Fiber optic applications• CATV applications

Terms• Attenuation: Attenuation is a general term that refers to• any reduction in the strength of a signal.

• Bandwidth: The amount of data that can be passed along a• communication medium in a given period of time.

• Decibel (dB): A unit used to express the difference in intensity,• usually between two acoustic, light, or electrical signals. In fiber• optics, the decibel is combined with the kilometer (dB/km) to form• the unit for measuring attenuation (signal loss) in a section of fiber.

• Electromagnetic Spectrum (EMS): This is a term that scientists• use when they want to talk about the vast range of energy• that radiates in every corner of the universe.

Terms - cont.• Electromagnetic Interference (EMI): A disturbance that affects• electrical circuits. It can degrade AM/FM radios, cell phones, • television reception…. It can occur naturally – sun flares, or • artificially. Any electronic device ever invented has the potential• to generate interference.

• Fiber-to-the-X (FTTX): A catch all acronym for all of the variations• on the use of fiber between the service and the customer. These• Include fiber-to-the-node (FTTN), fiber-to-the-curb (FTTC), fiber-to-• the-home (FTTH), and fiber-to-the-premise (FTTP).

• Kilo (k): A prefix in the International System of Units denoting the• number 1000. For example, a kilometer = 1000 meters.

Terms – cont.• Local Area Network (LAN): A local area network is a computer network

covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport.

• LASER: A laser is a device that emits light through a process called stimulated emission. In communication networks, a LASER is used

• to convert electrical signals (radio frequencies), into light signals.

• Master Telecommunications Center (MTC): The central location where Cox Communications, acquires and combines, all the

• services that are offered to our customers. The MTC is also• known as a “headend”.

• Metropolitan Area Network (MAN): A large LAN that typically can• span up to 50km.

Terms – cont.• Micron (μ): A unit of length equal to one millionth of a meter.

• Nano (n): A unit of length equal to one billionth of a meter. It is

• commonly used in fiber optics to differentiate between the various wavelengths of light. For example, the color blue has a wavelength of 475 nanometers.

• Optical receiver: In communication networks, it is the device that

• receives the light signals from a LASER and converts the light• signals back to electrical signals (radio frequencies).

Terms – cont.

Radio frequencies (RF): That part of the vast electromagnetic spectrum that can be harnessed for such purposes as

Terms – cont• Secondary Telecommunications Center (STC): The STC is a• smaller version of the MTC. The STC is also referred to as a

“hub”.

• Wide Area Network (WAN): Whereas a LAN (local area network) is a network that links computers, printers and other devices located in an office, a building or even a campus , a WAN (wide area network) is a system that extends for greater distances and is used to connect LANs (local area networks) together. A WAN can encompass

• networks across a state, the country as a whole, or the world.

Definition• An optical fiber is a glass or plastic strand that can carry information -• in the form of light, along its length. Optical fibers are widely used in • communications because they permit transmissions over longer• distances and at higher bandwidths (data rates) than traditional copper-• based networks.

• With very low attenuation ( signal loss), immunity from all electrical• interference, and high bandwidth capacity, optical fibers are almost• the perfect medium for communications.

Quick History• Though the use of fiber• optics is common in modern• communication networks, the• guiding of light through a clear• medium is a fairly simple concept.• Using a container of water, and a• simple light source, Daniel Colladon• and Jacques Babinet demonstrated• the guiding of light in Paris in the• early 1840s.

Lightsource

Waterreservoir

Light carriedby waterstream

Quick History – cont.• In more modern times, scientists worked on developing a fiber so pure that• when a light source was introduced at one end, after a distance of one • kilometer, one per cent of the light remained. In terms of attenuation (signal• loss), this was equal to 20 decibels – the existing transmission distance for a• copper-based telephone system.

• The crucial attenuation level of 20 decibel per kilometer was first achieved in• 1970 by Drs. Robert Maurer, Donald Beck, and Peter Schultz, of glass maker Corning• Incorporated. They demonstrated a fiber with an attenuation of 17dB/km.

• A few years later they produced a fiber with an attenuation of only 4dB/km. This• enabled General Telephone & Electronics to sent the first live telephone traffic• on April 22, 1977, in Long Beach, California.

• Today, the purity of glass enables attenuation levels of 0.35dB/km @ 1310nm, and• 0.5dB/km @ 1550nm. Combined with improvements in LASERs, optical receivers,• and other optical components, optical networks can transmit digitized signals long• distances – in many cases without the need of optical amplifiers.

Wavelengths of light• You may not be aware of it, but the electromagnetic• spectrum is quite familiar to you: The microwave• you heat your food with, the cell phone you keep in• touch with, your favorite television show, the light from• the sun that both warms and burns, plus the light your eyes• use to see; it is all part of the electromagnetic spectrum.

Wavelengths of light – cont.

• 1310 nm

• 1550 nm

Visible light:

Light not visible to the naked eye:

650nm

400 700

wavelength

Anatomy of an optical fiber

Three functional components:

CoreSilica glass with GermaniaPurpose – signal transmission

CladdingSilica glassPurpose – signal containment

CoatingDual-layer, UV cured acrylatePurpose – mechanical protection

Types of fibers

• Putting the micron (μ) in perspective

• A human red blood cell is 10 microns across.

• A human hair ranges from 40 – 120 microns wide.

• The period at the end of this sentence is about 397 microns.

• The eye of a typical needle is 749 microns wide.

• A postage stamp is @ 25,400 microns long.

Types of fibers – cont.

Multimode

Single-mode

PlasticCoating250 microns

Cladding125 microns

50 & 62.5 microns

8 – 10 microns 125μm 250μm

Types of fibers – cont.

Multimode fibersAdvantages

• Uses inexpensive light sources• Uses low cost connectors that are easy to install• Easier and cheaper to install• Works well for LAN, college campus networks• Easier to splice when cut• Can handle high data rates

Disadvantages

• Optimized for distances less than 2Km• Higher attenuation than single-mode fiber

Types of fibers – cont.

Single-mode fiber

Advantages

• Optimized for long haul applications• Very low attenuation• Light can reach distances of @ 50 miles without the need of optical amplifiers• Can handle high data rates

Disadvantages

• Uses expensive LASERs as a light source• Difficult to install connectors• Higher installation costs• More susceptible to damage during installation• More difficult to splice when cut

Types of fibers – cont.

Attenuation: Single-mode vs. Multimode

Single-mode

Multimode

Types of fibers – cont.250μm

900μm

Single bare fiber

Single fiber strand with additionalwhite plastic coating

Types of fibers – cont.

Buffer tubes

Individual fibers

• Up to 432 fibers for single-mode cable

Fiber glass support

Armor

Plastic

Rip cord

Mylar wrap

Fiber optic link

LASERInformation

SourceOpticalReceiver

InformationTo Customer

Model of "simple" fiber optic data link

fiber

Benefits vs. traditional networks

• Not susceptible to electro- magnetic or other types of electrical interference • Not affected by temperature• No amplification required up to @ 50 miles• Greater information carrying

capacity• Lightweight• More secure• Less attenuation than copper- based cables• Improved quality of the signals transmitted

Benefits vs. traditional networks - cont.

• Capacity of 2400 pair copper telephone cable:- 1 call per copper pair

• Capacity of a single fiber: - > 500,000 calls

• Size and weight– To transmit equivalent information

1 mile• Single fiber cable =28 lbs• Equivalent capacity copper

cable = 33 tons

Why use fiber?

Fiber optic applications

LA

N

B

B B

B

B

A

A A

A

A

Acc

ess

Metr

oLo

ng

Hau

lFiber-to-the-X(curb, building, home)0-10 km

LAN0-2 km

-WAN-Cross-country/Intercontinent-Submarine>200 km

MAN/city rings10 - 200 km

Cable applications

ServiceArea

Service Area

Tree-and-Branch

Hybrid-Fiber-Coaxial

MTC

Cable Networks

Long cascade of amplifiers

Service Area

Microwave

HUB

Cable applications – cont.

FiberAccessNetwork

FiberTransportNetwork

DistributionAmplifier

Line ExtenderAmplifierCoaxial

AccessNetwork

MTC Hub/STC

Ring-in-ring HFC Network