Introduction: History, components, applications, optical communication systems
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 1870, Tyndall (UK) Light guiding in a thin water jet.
 1880, William Wheeling patented a method of light transfer called "piping light".
 1880, Alexander Graham Bell developed an optical voice transmission system, the photophone (today, free-space optical links find extensive use in metropolitan applications).
 1951-1959, Heel, Hopkins, Kapany (UK) Image transmission w. fiber bundles.
 1957, Gordon Gould (USA) popularized the idea of using lasers.
 1962, Semiconductor lasers were first realized, most widely used in fiber optics today.
1870
1951-1959
2 http://www.fiber-optics.info/history

 1970, Drs. Robert Maurer, Donald Keck, and
Peter Schultz of Corning succeeded in developing a glass fiber that exhibited attenuation at less than 20 dB/km.
 1977, Nippon Telegraph and Telephone
(NTT) developed the 'third window' at 1550 nm, loss 0.2 dB/km.
 Early 1970's, the U.S. Navy installed a fiber optic telephone link aboard the U.S.S. Little
Rock
 1977, both AT&T and GTE installed fiber optic telephone systems in Chicago and
Boston respectively.
 1980, broadcasters of the Winter Olympics, in Lake Placid, New York, requested a fiber optic video transmission system for backup video feeds.
Four Wavelength Regions of Optical Fiber, 850,
1310, 1550, 1625
3 http://www.fiber-optics.info/history

 1990, Bell Labs transmitted a 2.5 Gb/s signal over 7,500 km without regeneration.
 1998, Bell Labs transmitted 100 simultaneous optical signals, each at a data rate of 10 Gb/s for a distance of nearly 250 miles (400 km).
 Today, DWDM technology continues to develop.
 The 'last mile' for optical fiber goes from the curb to the television set top, known as fiber-to-the-home (FTTH) and fiber-to-the-curb (FTTC), http://www.fiber-optics.info/history
Projected Internet
Traffic Increases
The Growth of Optical Fiber
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Transmission Capacity

 Optical Fiber is the backbone of modern communication networks
 Voice (SONET/Telephony) - The largest traffic
 Video (TV) over Hybrid Fiber Coaxial (HFC)
 Fiber Twisted Pair for Digital Subscriber
Loops (DSL)
 Multimedia (Voice, Data and Video) over
DSL or HFC
Information revolution wouldn’t have happened without the Optical Fiber
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EDFA: Erbium Doped Fiber Amplifier
HDTV: High-definition television
LAN: Local Area Network
OT: Optical Transceiver 6

 Lowest attenuation  attenuation in the optical fiber (at
1.3 µ m and 1.55 µ m bands) is much smaller than electrical attenuation in any cable at useful modulation frequencies
 Much greater distances are possible without repeaters
 This attenuation is independent of bit rate
 Highest Bandwidth (broadband)  high-speed
 Single Mode Fiber (SMF) offers the lowest dispersion  highest bandwidth  rich content
 Upgradability: Optical communication system can be upgraded to higher bandwidth, more wavelengths by replacing only the transmitters and receivers
 Low Cost for fiber
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Major Elements of An Optical Fiber Link
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 Digital fiber optic (SONET) systems in the backbone – Mostly deployed
 Dynamic multi-access Ethernet systems – LAN,
GPON, EPON Access Networks
 Microwave (analog) fiber optic (MFO) Systems –
CATV, Satellite base stations
 Radio over fiber systems for wireless communications (ROF)
 Infrared optical-wireless systems (Free Space
Optics, IrDA)
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Core/
LongHaul
Metro/
Regional
Access/
LocalLoop
Who Uses it?
Phone
Company,
Gov’t(s)
Phone
Company, Big
Business
Small
Business,
Consumer
Span
(km)
Bit Rate
(bps)
~10 3 ~10 11
(100’s of
Gbps)
~10 2 ~10 10
(10’s of
Gbps)
~10 ~10 9
(56kbps-
1Gbps)
Multiplexing
DWDM/
TDM
DWDM/C
WDM/TD
M
TDM/
SCM/
Fiber
SMF/ DCF EML/
DFB
SMF/
LWPF
SMF/
MMF
Laser
DFB
DFB/ FP
Receiver
APD
APD/ PIN
PIN
Core - Combination of switching centers and transmission systems connecting switching centers.
Access- that part of the network which connects subscribers to their immediate service providers.
LWPF : Low-Water-Peak Fiber, DCF : Dispersion Compensating Fiber, EML : Externally modulated (DFB) laser
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Fiber in Backbone: Synchronous Optical
Network (SONET/SDH)
 SONET is the TDM optical network standard for North America (called SDH in the rest of the world)
 We focus on the physical layer
 STS-1, Synchronous Transport Signal consists of 810 bytes over 125 us
 27 bytes carry overhead information
 Remaining 783 bytes: Synchronous
Payload Envelope
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SONET
OC-1
OC-3
OC-12
OC-24
OC-48
OC-96
OC-192
Bit Rate (Mbps)
51.84
155.52
622.08
1244.16
2488.32
4976.64
9953.28
SDH
-
STM-1
STM-4
STM-8
STM-16
STM-32
STM-64
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Fiber in The
Access End
 Passive Optical Networks
(PON) – No active elements or O/E conversion (GPON,
EPON etc)
 Fibre-Coaxial (analog) or
DSL (digital) fibre-copper systems
 Radio over fibre (Fibre-
Wireless) Systems
Currently driving the market
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Three basic types of TDM-PON : A/BPON, EPON, GPON
 APON/BPON: ATM/Broadband PON
 Uses ATM as bearer protocol
 Started with a shared data rate of 54 Mb/s
 Later upgraded to155 or 622 Mbps downstream, 155 upstream.
 EPON: Ethernet PON
 Uses Ethernet frames and Multi-Point Control Protocol (MPCP) for data transfer
 10G-EPON project launched in 2006
 Aims at reaching high data rates of 10 Gb/s
 IEEE 802.3 working group has formed a 10G-EPON task force
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 GPON: Gigabit capable PON - successor of BPON
 Enables the transmission of both ATM cells and Ethernet packets in the same transmission frame structure.
 To accommodate multiple services efficiently, it uses a GPON
Encapsulation Method (GEM).
 WPON: WDM-PON
 Support multiple wavelengths
 uses multiple wavelengths in a single fiber to multiply the capacity without increasing the data rate.
 Hybrid PONs proposed
 WDM-Ethernet
 DWDM-TDM
 Long reach PONs
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APON
BPON
EPON
GPON
Downstream
155 Mb/s
622 Mb/s
155 Mb/s
622 Mb/s
10-1000 Mb/s
1.244 Gb/s
2.488 Gb/s
Upstream
155 Mb/s
155 MB/s
155 Mb/s
622 MB/s
10-1000 Mb/s
155 Mb/s
622 Mb/s
1.244 Gb/s
2.488 Gb/s
Standard
ITU-T (FSAN)
IEEE 802.3ah
ITU-T G.983
(FSAN)
ITU-T G.983
(FSAN – Full
Services Access
Network)
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Microwave Fiber Optic (MFO) Analog
Systems
 Modulating signal is analog (RF)
 Several RF carriers are freq. multiplexed over single fiber called Sub Carrier
Multiplexing
 Each RF Carrier is an independent communication channel
 Ex: CATV Systems
 Linearity is the biggest concern
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Hybrid/Fiber Coax (HFC) TV Networks
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 DSL consists of fiber-twisted pair
 This is a digital fiber-copper link
 Multimedia (video and data) supported over voice
 At least 3.7 Mb/s streaming is needed for quality video
 Bit rate heavily depend on the length of the twisted pair link
 New techniques like very high rate DSL (VDSL) are tried
 Some new condominiums in Toronto have access to video over DSL
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Radio over Fiber (ROF) for Wireless
Systems: Technology
A subset of MFO systems. However, the microwave signal is transmitted into the free-space to give wireless access and mobility. Gives unique challenges.
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ROF for Wireless Systems: Multi
Standard Fiber-Wireless
Central
Base
Station
Radio over Fiber (ROF)
RAP
(Simple)
Up/Down links
Y
Y
RAP
802.11
Y
RAP voice
Single ROF link can support voice and data simultaneously
Micro
Cell
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 Fiber has the capability to transmit hundreds of wavelengths
 Cost effective only in long haul links in the past
 With low cost Coarse WDM (CWDM) equipment this is possible even in the access front
 Once the fiber is in place, additional wavelength can be launched at both ends by replacing transceivers
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Communication Systems: Digital
Transmission Hierarchy
Called Telephony or T-Networks
Uses Copper
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Purpose:
 Eliminate repeaters in T-1 systems used in inter-office trunk lines
Technology:
 0.8 µ m GaAs semiconductor lasers
 Multimode silica fibers
Limitations:
 Fiber attenuation
 Intermodal dispersion
Deployed since 1974
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Opportunity:
 Development of low-attenuation fiber (removal of H2O and other impurities)
 Eliminate repeaters in long-distance lines
Technology:
 1.3 µ m multi-mode semiconductor lasers
 Single-mode, low-attenuation silica fibers
 DS-3 signal: 28 multiplexed DS-1 signals carried at 44.736
Mbits/s
Limitation:
 Fiber attenuation (repeater spacing ≈ 6 km)
Deployed since 1978
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Opportunity:
 Deregulation of long-distance market
Technology:
 1.55 µ m single-mode semiconductor lasers
 Single-mode, low-attenuation silica fibers
 OC-48 signal: 810 multiplexed 64-kb/s voice channels carried at 2.488 Gbits/s
Limitations:
 Fiber attenuation (repeater spacing ≈ 40 km)
 Fiber dispersion
Deployed since 1982
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Opportunity:
 Development of erbium-doped fiber amplifiers (EDFA)
Technology (deployment began in 1994):
 1.55 µ m single-mode, narrow-band semiconductor lasers
 Single-mode, low-attenuation, dispersion-shifted silica fibers
 Wavelength-division multiplexing of 2.5 Gb/s or 10 Gb/s signals
Nonlinear effects limit the following system parameters:
 Signal launch power
 Propagation distance without regeneration/re-clocking
 WDM channel separation
 Maximum number of WDM channels per fiber
Polarization-mode dispersion limits the following parameters:
 Propagation distance without regeneration/re-clocking
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Evolution of Optical Networks
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History of
Attenuation
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Three Windows based on
Wavelength
The operating range of optical fiber systems and characteristics of four key link components
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