Introduction to Fiber Optics - Alliance for Community Media

Report
Introduction to Fiber Optics
Presented by: James Carter
Sales Engineer – Cox Business
Scope
This presentation is designed to give a general
overview of fiber optic theory, its construction,
the two basic types of fibers, and the benefits
of 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-tothe-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 copperbased 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.
Light
Water
reservoir
source
Light carried
by water
stream
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.
Visible light:
650nm
400
700
Light not visible to the naked eye:
wavelength
• 1310 nm
• 1550 nm
Anatomy of an optical fiber
Three functional components:
Core
Silica glass with Germania
Purpose – signal transmission
Cladding
Silica glass
Purpose – signal containment
Coating
Dual-layer, UV cured acrylate
Purpose – 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.
50 & 62.5 microns
Cladding
125 microns
Plastic
Coating
250 microns
Multimode
8 – 10 microns
Single-mode
125μm
250μm
Types of fibers – cont.
Multimode fibers
Advantages
Disadvantages
• 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
• 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
Single bare fiber
900μm
Single fiber strand with additional
white plastic coating
Types of fibers – cont.
Fiber glass support
Buffer tubes
Rip cord
Armor
Individual fibers
Mylar wrap
Plastic
• Up to 432 fibers for
single-mode cable
Fiber optic link
fiber
Information
Source
LASER
Optical
Receiver
Model of "simple" fiber optic data link
Information
To Customer
Benefits vs. traditional networks
•
•
•
•
•
•
•
•
Not susceptible to electromagnetic 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 copperbased cables
Improved quality of the signals
transmitted
Benefits vs. traditional networks - cont.
Why use fiber?
•
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
Fiber optic applications
MAN/city rings
10 - 200 km
LAN
AB
B
Access
A B
B
Long Haul
A
B
A
-WAN
-Cross-country/Intercontinent
-Submarine
>200 km
Metro
A
Fiber-to-the-X
(curb, building, home)
0-10 km
LAN
0-2 km
Cable applications
Cable Networks
MTC
Tree-and-Branch
Service
Area
Long cascade of amplifiers
Microwave
HUB
Hybrid-Fiber-Coaxial
Service
Area
Service
Area
Cable applications – cont.
Ring-in-ring HFC Network
MTC
Hub/STC
Fiber
Transport
Network
Fiber
Access
Network
Distribution
Amplifier
Coaxial
Access
Network
Line Extender
Amplifier

similar documents