Optical Fiber Communication | FTTH
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Transcript of Optical Fiber Communication | FTTH
UNRAVELLING FIBERS
AND FIBER TO THE HOME
Prepared By:Vanhishikha
Bhargava(0941631056)
CONTENTS
Introduction to fiber optics and its Evolution Basics of optical fiber Color coating Wavelength bands-Transmission windows Types of optical fibers Advantages and Disadvantages Applications Connectors Adapters Attenuators Losses in optical fiber Splitters and types Field assembly connectors Cables and types Splicing and types Wavelength Division Multiplexing and Types
INTRODUCTION
Communications systems that carry information through a guided fiber cable are called fiber optic systems.
Use of optical fibers to replace conventional transmission lines and microwave wave-guide in telecommunication systems.
Light is effectively the same as RF radiation but at a much higher frequency, theoretically the information-carrying capacity of a fiber is much greater than that of microwave radio systems.
As they are not electrically conductive, hence very suitable for use in areas where electrical isolation and interference are severe problems.
EVOLUTION OF FIBER
1880 – Alexander Graham Bell 1930 – Patents on tubing 1950 – Patent for two-layer glass wave-guide 1960 – Laser first used as light source 1965 – High loss of light discovered 1970s – Refining of manufacturing process 1980s – OF technology becomes backbone of
long distance telephone networks in NA.
OPTICAL FIBER
Optical fiber is made from thin strands of either glass or plastic
It has little mechanical strength, so it must be enclosed in a protective jacket
Often, two or more fibers are enclosed in the same cable for increased bandwidth and redundancy in case one of the fibers breaks
It is also easier to build a full-duplex system using two fibers, one for transmission in each direction
TOTAL INTERNAL REFLECTION
Optical fibers work on the principle of total internal reflection
With light, the refractive index is listed The angle of refraction at the interface
between two media is governed by Snell’s law:
REFRACTION
air
glass
normal
incident ray
angle of refraction
angle of incidence
refracted ray
NUMERICAL APERTURE
The angle of acceptance is twice that given by the numerical aperture
RAYLEIGH'S SCATTERING
Rayleigh scattering is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light.
It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases.
FRESNEL’S REFLECTION
When light moves from a medium of a given refractive index n1 into a second medium with refractive index n2, both reflection and refraction of the light may occur.
The relationship between these angles is given by the law of reflection:
COLOR COATING
TUBE COLOR ABBREVIATION
1 BLUE BL
2 ORANGE OR
3 GREEN GR
4 BROWN BR
5 SLATE SL
6 WHITE WH
7 RED RD
8 BLACK BK
9 YELLOW YW
10 VIOLET VI
11 ROSE RS
12 AQUA AQ
WAVELENGTH BAND
Fiber optic system transmit using infrared light, invisible to human eye, because it goes further in the optical fiber at those wavelength.
TRANSMISSION WINDOW
Band Wavelength range Description
O- band 1260 nm- 1360 nm Original band
E- band 1360 nm- 1460 nm Extended band
S- band 1460nm- 1530 nm Short wavelength band
C- band 1530 nm- 1565 nm Conventional band
L- band 1565 nm- 1625 nm Long wavelength band
U- band 1625 nm- 1675 nm Ultra long wavelength band
FIBER COMPOSITION
Core – thin glass center of the fiber where light travels.
Cladding – outer optical material surrounding the core
Buffer Coating – plastic coating that protects the fiber.
TYPES OF OPTICAL FIBERS
OPTICAL FIBERS
MULTIMODE FIBERS
STEP INDEX
GRADED INDEX
OM1/OM2/OM3
SINGLEMODE FIBERS
STEP INDEX
SINGLE-MODE STEP-INDEX FIBER
Used to transmit one signal per fiber. Used in telephone and cable TV. They have small cores(9 microns in diameter) . Transmit infra-red light from laser.
MULTI-MODE STEP-INDEX FIBER
Used to transmit many signals per fiber. Used in computer networks. They have larger cores(62.5/50 microns in
diameter) Transmit infra-red light from LED.
MULTI-MODE GRADED-INDEX FIBER
Core diameter : 50/62.5 microns. Cladding size: 125-140 microns. Refractive index changes continuously. Low dispersion. Core refractive index is made to vary as a function of
the radial distance from the center of the fiber.
OM1/OM2/OM3
OM1: refer to the commonly used 62.5/125 multimode fiber.
OM2: refer to the commonly used 50/125 cable. Both OM1 and OM2 easily supports applications
ranging from Ethernet to gigabit Ethernet. OM3: Typically this fiber optic patch cable is with
50/125 multimode fiber, with aqua jacket. They support bandwidth up to 10GB upto 300
meters.
ADVANTAGES
Wide bandwidth Light weight and small size Immunity to electromagnetic interference Lack of EMI cross talk between channels Lack of sparking Compatibility with solid state sources Low cost No emission licenses
DISADVANTAGES
High investment cost Need for more expensive transmitters and
receivers Fragility Opaqueness Requires special skills
APPLICATIONS
Telecommunications Local Area Networks Cable TV CCTV Optical Fiber Sensors Video Surveillance Links
FIBER OPTIC CONNECTORS
Terminates the fibers Connects to other fibers or transmission equipment
FIBER CONNECTOR TYPE
E 2000
FSMA FDDI
MPO BICONICMT- RJLC
STFCSC
FERRULE POLISH
To avoid an air gap Ferrule is polished flat,
or Rounded (PC—
Physical Contact), or Angled (APC)
Reduces reflectance Cannot be mated
with the other polish types
ADAPTERS
SC ST MT- RJ
LC
FC
E 2000
FSMA
MPO
BICONIC
FDDI
ATTENUATORS
SC LC FC
ST E 2000
MPO
MT- RJ
ATTENUATORS
VARIABLE ATTENUATORS
Ideal for adjusting OEM systems in production and lab applications.
These attenuators also exhibit low back reflection and good temperature stability.
FIXED ATTENUATORS
Fixed attenuators can limit, or attenuate. The amount of light passing through to the exact level your project.Used in applications where a pre-determined amount of light loss is specified.Most commonly used for test and measurement, optical sensors, and telecommunications applications.
TYPES OF LOSSES
LOSSES
ATTENUATION
SCATTERING
ABSORPTION
DISPERSION
MODAL
CHROMATIC
POLARISATIO
N MODE
LOSS MECHANISM
DISPERSION
MODAL DISPERSION
Modal dispersion is a distortion mechanism occurring in multimode fibers and other waveguides, in which the signal is spread in time because the propagation velocity of the optical signal is not the same for all modes.
POLARIZATION MODE DISPERSION
A special case of modal dispersion is polarization mode dispersion (PMD), a fiber dispersion phenomena usually associated with single-mode fibers. PMD results when two modes that normally travel at the same speed due to fiber core geometric and stress symmetry, travel at different speeds due to random imperfections that break the symmetry
CHROMATIC DISPERSION
Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency.
Dispersion is sometimes called chromatic dispersion to emphasize its wavelength-dependent nature.
SPLITTERS
A splitter is a device used to split the cable signal if the signal must be sent to two or more devices.
Optical splitters are also known as couplers. They are base on the type of cable management product they will be using.
Performance specifications of the splitters are given by the ITU- T G671 standard.
TYPES OF SPLITTERS
FUSED BICONICAL TAPER
SPLITTERS
PLANAR LIGHTWAVE CIRCUITS
FUSED BICONICAL TAPER SPLITTER
These are also known as singlemode splitters..
Operating wavelength is 1310nm or1550nm and the passband is 80nm.
The coupling ratio can change from 1:99 to 50:50.
Low insertion loss. Low excess loss. High directivity. Low polarization related
loss. More channels.
PLANAR LIGHTWAVE CIRCUITS
These type of splitters are smaller in footprint.
They offer slightly better losses across their split ratios than FBTs
Low insertion loss. Low excess loss. High directivity. High stability.
FIELD ASSEMBLY CONNECTORS
Designed for simple and fast field termination of single fibers, without polishing or adhesives.
The heart of the Quick-SC fast connector is a pre-polished ferrule and a mechanical splice inside the connector body.
Compatible with conventional SC and LC connector.
Easy and fast assembly without special tool
Reliable assembly with Assembly Jig and Fiber Holder appended to connector kit
CABLES
Fiber optic "cable" refers to the complete assembly of fibers, strength members and jacket. Fiber optic cables come in lots of different types, depending on the number of fibers and how and where it will be installed. There are classified as :
Cables (armored) Cables (unarmored) Distribution cables Drop cables
Cables (armored)
Duplex armored
Zipcord
Zipcord(round)
Simplex armored
Cables (unarmored)
Duplex unarmored
Zipcord
Zipcord(round)
Simplex unarmored
Distribution cables
4-fiber 8-fiber 12-fiber
24-fiber
Drop cables
1-fiber 2-fiber 4-fiber1-fiber
(messenger wire)
2-fiber(messenge
r wire)
SPLICES
Splices are a permanent join of two fibers
Lower attenuation and reflectance than connectors Stronger and cheaper than connectors Easier to perform than connectorization Mass splicing does 12 fibers at a time, for ribbon
cables
SPLICER
FUSION SPLICING
Melts the fibers together to form a continuous fiber
Expensive machine Strongest and best join for singlemode fiber
May lower bandwidth of multimode fiber
MECHANICAL SPLICING
Mechanically aligns fibers Contains index-matching gel to transmit light Equipment cost is low Per-splice cost is high Quality of splice varies, but better than
connectors Fiber alignment can be tuned using a Visual Fault
Locator
COMPARISON
Mechanical splicing
Fusion splicing
Reflection losses(-45 db to -55 db)
No reflection losses
Insertion loss(0.2 db)
Very low insertion loss(0.1 db to .15 db)
cost – high Comparatively less
WAVELENGTH DIVISION MULTIPLEXING
Data from each TDM channel is loaded on one optical frequency (or wavelength, ) of a particular wavelength band
These wavelengths are then multiplexed onto one fiber with the help of WDM multiplexers
Other side of the network these wavelengths are demultiplexed by using either optical filters, gratings or WDM demultiplexer
DENSE WAVELENGTH DIVISION MULTIPLEXING
Can achieve high system capacity by multiplexing
more WDM channels, each with relatively low data rate
Consist of a WDM combined with an optical amplifier,
to allow multiple wavelengths on a single fiber and
also avoid individual regeneration equipment for each
wavelength by use of line amplifiers
COARSE WAVELENGTH DIVISION MULTIPLEXING
o The total CWDM optical span to somewhere near 60 km for a 2.5 Gbit/s signal.oCWDM is also being used in cable television networks, where different wavelengths are used for the downstream (1310 nm) and upstream (1550 nm) signals. o Signals are not spaced appropriately for amplification by EDFAs. o Passive CWDM is an implementation of CWDM that uses no electrical power and separates the wavelengths using band pass filters and prisms.
ANY QUESTIONS OR COMMENTS?
THANK YOU