Dense wavelength division multiplexing 1
KuttiVinoth
34 views
132 slides
Sep 30, 2024
Slide 1 of 132
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
About This Presentation
DWDM
Slide Content
EAGLE PHOTONICS
Multiplexing Techniques
Multiplexing Techniques
EAGLE PHOTONICS
Multiplexing
•Multiplexing is a process of putting all the
signals into a common channel in different
ways and the component is called
multiplexer
•De-multiplexing is a process which separates
out all the multiplexer signals and the
component is called de-multiplexer
•This is required to increase system overall
capacity
Multiplexing
•Multiplexing is a process of putting all the
signals into a common channel in different
ways and the component is called
multiplexer
•De-multiplexing is a process which separates
out all the multiplexer signals and the
component is called de-multiplexer
•This is required to increase system overall
capacity
EAGLE PHOTONICS
Multiplexing Techniques
•Time-division multiplexing (TDM)
•Wavelength-division multiplexing (WDM)
•Subcarrier multiplexing (SCM)
•Code-division multiplexing (CDM)
•Polarization-division multiplexing (PDM)
•Hybrid Types: WDM/TDM, WDM/SCM, etc
Multiplexing Techniques
•Time-division multiplexing (TDM)
•Wavelength-division multiplexing (WDM)
•Subcarrier multiplexing (SCM)
•Code-division multiplexing (CDM)
•Polarization-division multiplexing (PDM)
•Hybrid Types: WDM/TDM, WDM/SCM, etc
EAGLE PHOTONICS
TDM - Time Division Multiplexing
•Combines traffic from multiple inputs
onto one common high capacity output
•Requires electrical mux/demux function
TDM - Time Division Multiplexing
•Combines traffic from multiple inputs
onto one common high capacity output
•Requires electrical mux/demux function
EAGLE PHOTONICS
DWDM Technology
DWDM Technology
EAGLE PHOTONICS
EAGLE PHOTONICS
What is Wave 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
demultiplexers
What is Wave 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
demultiplexers
EAGLE PHOTONICS
Increased Network Capacity
Independence Of Bit Rates And Formats
DWDM = Dense WDM
Increased Network Capacity
Independence Of Bit Rates And Formats
DWDM = Dense WDM
EAGLE PHOTONICS
DWDM
•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
DWDM
•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
EAGLE PHOTONICS
EAGLE PHOTONICS
Why WDM?
•Better utilization of fiber
•Overcome ‘fiber exhaust’, lack of fiber availability
•Low unit cost of bandwidth in high capacity systems
•Easily integrated with existing equipment in the
network
•Bit-rate and protocol independent interface
•Wavelength leasing instead of Bandwidth leasing
Why WDM?
•Better utilization of fiber
•Overcome ‘fiber exhaust’, lack of fiber availability
•Low unit cost of bandwidth in high capacity systems
•Easily integrated with existing equipment in the
network
•Bit-rate and protocol independent interface
•Wavelength leasing instead of Bandwidth leasing
EAGLE PHOTONICS
Limitations of TDM Technology
•Maximum TDM line rate one can get in market to
date is 10 Gbps
•40 Gbps is undergoing field trails, but
associated with lot of problem
–In making systems
–Testing and measurement equipments
–Degradation of fiber transmission
–Cost in having protection system
–Overall cost of the network
Limitations of TDM Technology
•Maximum TDM line rate one can get in market to
date is 10 Gbps
•40 Gbps is undergoing field trails, but
associated with lot of problem
–In making systems
–Testing and measurement equipments
–Degradation of fiber transmission
–Cost in having protection system
–Overall cost of the network
EAGLE PHOTONICS
Limitations of TDM Technology
•Line cards and other hardware required to
be changed to increase capacity
•Operators tend to build TDM networks
with higher capacity than required,
considering future capacity requirements
•TDM data rates stagnating at 10 Gbps
–Beyond 10 Gbps capacity increase is realized
by building parallel SDH networks
–Each SDH/SDH system required 2 fiber
without protection and 4 fibers with
protection
–So fiber exhaust?
Limitations of TDM Technology
•Line cards and other hardware required to
be changed to increase capacity
•Operators tend to build TDM networks
with higher capacity than required,
considering future capacity requirements
•TDM data rates stagnating at 10 Gbps
–Beyond 10 Gbps capacity increase is realized
by building parallel SDH networks
–Each SDH/SDH system required 2 fiber
without protection and 4 fibers with
protection
–So fiber exhaust?
EAGLE PHOTONICS
Limitations of TDM Technology
Optical Fiber
Data Channel (Bit Rate=x)
Data Channel (Bit Rate =
x)
TX
TX
RX
RX
Optical
fiber
Optical
fiber
New
TX/RX
required
Limitations of TDM Technology
Optical Fiber
Data Channel (Bit Rate=x)
Data Channel (Bit Rate =
x)
TX
TX
RX
RX
Optical
fiber
Optical
fiber
New
TX/RX
required
EAGLE PHOTONICS
Limitations of TDM Technology
Regenerators
40 Gbps (4 x 10 Gbps)
Capacity
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
Limitations of TDM Technology
Regenerators
40 Gbps (4 x 10 Gbps)
Capacity
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
EAGLE PHOTONICS
Limitations of TDM Technology
•Propagation delays due to O-E-O conversion
–All SDH NEs do O-E-O conversion for
processing of overhead information
–O-E-O conversion slows down the signal
•SDH not the ideal carrier for data traffic
–Data traffic has its own overheads
–SDH overheads are partly redundant while
carrying data traffic
Limitations of TDM Technology
•Propagation delays due to O-E-O conversion
–All SDH NEs do O-E-O conversion for
processing of overhead information
–O-E-O conversion slows down the signal
•SDH not the ideal carrier for data traffic
–Data traffic has its own overheads
–SDH overheads are partly redundant while
carrying data traffic
EAGLE PHOTONICS
Purpose of WDM
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
Traditional Network with Repeaters, no WDM
75% fewer fibers
WDM Network
with Repeaters
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
75% less equipment
WDM Network with
Optical Amplifiers
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
Purpose of WDM
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
Traditional Network with Repeaters, no WDM
75% fewer fibers
WDM Network
with Repeaters
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
75% less equipment
WDM Network with
Optical Amplifiers
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
EAGLE PHOTONICS
TDM and WDM
TDM and WDM
EAGLE PHOTONICS
WDM Classifications
•Classification of WDM is based on the
channel spacing between the two
wavelengths
•Channel spacing > 200 GHz called CWDM
•Channel spacing < 100 GHz called DWDM
•Channel spacing < 25 GHz called UDWDM
0.8 nm = 100 GHz0.8 nm = 100 GHz
•Classification of WDM is based on the
channel spacing between the two
wavelengths
•Channel spacing > 200 GHz called CWDM
•Channel spacing < 100 GHz called DWDM
•Channel spacing < 25 GHz called UDWDM
0.8 nm = 100 GHz0.8 nm = 100 GHz
EAGLE PHOTONICS
CWDM
CWDM
EAGLE PHOTONICS
WDM
WDM
EAGLE PHOTONICS
DWDM
DWDM
EAGLE PHOTONICS
DWDM Bands
Wavelength band available for communication
• C band (1530nm - 1565nm, 35 nm)
• L band (1565nm - 1610nm, 45 nm)
DWDM Bands
Wavelength band available for communication
• C band (1530nm - 1565nm, 35 nm)
• L band (1565nm - 1610nm, 45 nm)
EAGLE PHOTONICS
Wavelength Bands
Wavelength Bands
EAGLE PHOTONICS
Wavelength (nm)
Wavelength (nm)
OSC
1510
OSC
1625
OSC
1510
OSC
1625
1547.72 nm – 1559.79 nm –( band)
1528.77 nm – 1540.56 nm –( band)
channel
channel
123456789 1110 1312 141516
123456789 1110 1312 141516
ITU Wavelength GridITU Wavelength Grid
Wavelength (nm)
Wavelength (nm)
OSC
1510
OSC
1625
OSC
1510
OSC
1625
1547.72 nm – 1559.79 nm –( band)
1528.77 nm – 1540.56 nm –( band)
channel
channel
123456789 1110 1312 141516
123456789 1110 1312 141516
ITU Wavelength GridITU Wavelength Grid
EAGLE PHOTONICS
Wavelength spacing
1528.77
nm
196.1 THz
1562.23 nm
191.9THz
1528.77 nm
196.1 THz
1562.23 nm
191.9THz
40-Channels, 100 GHz Spacing
80-Channels, 50 GHz Spacing
Wavelength spacing
1528.77
nm
196.1 THz
1562.23 nm
191.9THz
1528.77 nm
196.1 THz
1562.23 nm
191.9THz
40-Channels, 100 GHz Spacing
80-Channels, 50 GHz Spacing
EAGLE PHOTONICS
DWDM Types
•Unidirectional & Bi-Directional
•Transponder based systems
•Passive & Active
DWDM Types
•Unidirectional & Bi-Directional
•Transponder based systems
•Passive & Active
EAGLE PHOTONICS
Unidirectional
Unidirectional
EAGLE PHOTONICS
Unidirectional
Unidirectional
EAGLE PHOTONICS
Bi directional
Bi directional
EAGLE PHOTONICS
Bi-directional
Bi-directional
EAGLE PHOTONICS
Unidirectional versus Bidirectional
•Unidirectional
–More popular
–Ideal for high capacity growth
•Bidirectional system
–Ideal when there are fiber constraints
–Unsuitable for large capacity
Unidirectional versus Bidirectional
•Unidirectional
–More popular
–Ideal for high capacity growth
•Bidirectional system
–Ideal when there are fiber constraints
–Unsuitable for large capacity
EAGLE PHOTONICS
Transponder Based DWDM
•Transponder is a device that performs an
optical-electrical-optical conversion to a
specific wavelength
•Allows the input of any wavelength to DWDM
•Allows better performance due to control of
input power, dispersion matching of
transmitters, allows use of non-ITU grid
•Better for wavelength leasing, as customer
can send any wavelength and any
wavelength pipe in the network can be used,
requires a bit-rate flexible transponder
Transponder Based DWDM
•Transponder is a device that performs an
optical-electrical-optical conversion to a
specific wavelength
•Allows the input of any wavelength to DWDM
•Allows better performance due to control of
input power, dispersion matching of
transmitters, allows use of non-ITU grid
•Better for wavelength leasing, as customer
can send any wavelength and any
wavelength pipe in the network can be used,
requires a bit-rate flexible transponder
EAGLE PHOTONICS
Transponders
1310nm
1550nm
1530nm
1540nm
Transponders
(Wavelength Translators)
Transponders in
Terminal Transponders in
OADM
OADM
1310nm 1550nm
1600nm 1560nm
Any
wavelength
from 1300-
1600nm
Any one
wavelength
from ITU-grid
Transponders
1310nm
1550nm
1530nm
1540nm
Transponders
(Wavelength Translators)
Transponders in
Terminal Transponders in
OADM
OADM
1310nm 1550nm
1600nm 1560nm
Any
wavelength
from 1300-
1600nm
Any one
wavelength
from ITU-grid
EAGLE PHOTONICS
Types of Transponders
•Protocol specific transponders
–SONET, GigE Transponders available
•Transponders with open interfaces
–Protocol independent, hence flexibility of
application
–Incoming signals transparently transported
over DWDM
–Does not take care of OAM & P Functionality
provided in protocols like SONET
Types of Transponders
•Protocol specific transponders
–SONET, GigE Transponders available
•Transponders with open interfaces
–Protocol independent, hence flexibility of
application
–Incoming signals transparently transported
over DWDM
–Does not take care of OAM & P Functionality
provided in protocols like SONET
EAGLE PHOTONICS
Types of Transponders
•FEC Transponders
–Suitable for error prone links, systems
•High Dispersion Tolerant Transponders
–Uses narrow pulse width laser /
modulation
–Used to increase tolerance to
dispersion
Types of Transponders
•FEC Transponders
–Suitable for error prone links, systems
•High Dispersion Tolerant Transponders
–Uses narrow pulse width laser /
modulation
–Used to increase tolerance to
dispersion
EAGLE PHOTONICS
DWDM - Non-Transponder Based DWDM - Non-Transponder Based
•Non-transponder system have the light wave
system transmitter directly input to the DWDM
•Cheaper than transponder based systems, do
not have to buy the transmitter twice (once in
LTE and once in DWDM)
•Requires LTE to be equipped with laser TX of
the exact wavelength
•More flexible for wavelength leasing, as long as
customer supplies proper wavelength can use
any bit-rate any protocol
DWDM - Non-Transponder Based DWDM - Non-Transponder Based
•Non-transponder system have the light wave
system transmitter directly input to the DWDM
•Cheaper than transponder based systems, do
not have to buy the transmitter twice (once in
LTE and once in DWDM)
•Requires LTE to be equipped with laser TX of
the exact wavelength
•More flexible for wavelength leasing, as long as
customer supplies proper wavelength can use
any bit-rate any protocol
EAGLE PHOTONICS
Active vs. Passive WDM
•Active means optical amplifiers
•Allows long spans without regeneration equipment
•One line amp can do the work of many regenerators
•Passive means only the WDM equipment, no
amplification
•Useful for short distances where amplification is not
needed
•Avoids expensive OP-Amps
•Adds attenuation loss to the span, shortens
maximum span for non-amplified equipment
Active vs. Passive WDM
•Active means optical amplifiers
•Allows long spans without regeneration equipment
•One line amp can do the work of many regenerators
•Passive means only the WDM equipment, no
amplification
•Useful for short distances where amplification is not
needed
•Avoids expensive OP-Amps
•Adds attenuation loss to the span, shortens
maximum span for non-amplified equipment
EAGLE PHOTONICS
Fiber used for DWDM Applications
•DSF (Dispersion shifted fiber)
•+ NZ-DSF (Positive dispersion shifted fiber )
•- NZ-DSF (Negative dispersion shifted fiber)
•LEAF (Larger effective area fiber)
•G.653 – Characteristics of a dispersion-shifted
single-mode optical fiber cable
•G.654 – Characteristics of a 1550 nm wavelength
loss-minimized single-mode optical fiber cable
•G.655 – Characteristics of a non-zero dispersion
single-mode optical fiber cable
Fiber used for DWDM Applications
•DSF (Dispersion shifted fiber)
•+ NZ-DSF (Positive dispersion shifted fiber )
•- NZ-DSF (Negative dispersion shifted fiber)
•LEAF (Larger effective area fiber)
•G.653 – Characteristics of a dispersion-shifted
single-mode optical fiber cable
•G.654 – Characteristics of a 1550 nm wavelength
loss-minimized single-mode optical fiber cable
•G.655 – Characteristics of a non-zero dispersion
single-mode optical fiber cable
EAGLE PHOTONICS
Why DWDM - Incremental Capacity
Growth
Why DWDM - Incremental Capacity
Growth
EAGLE PHOTONICS
WDM Networks Evolution
•First GenerationFirst Generation:: Dense WDM networks
with linear architecture used in point-to-
point link, as a high bandwidth pipes
between two network elements. These
systems are integrated with optical
amplifiers and electronic regenerators
WDM Networks Evolution
•First GenerationFirst Generation:: Dense WDM networks
with linear architecture used in point-to-
point link, as a high bandwidth pipes
between two network elements. These
systems are integrated with optical
amplifiers and electronic regenerators
EAGLE PHOTONICS
WDM Networks Evolution
•Second GenerationSecond Generation:: WDM networks with
ring and mesh architectures. These
systems are integrated with optical
amplifiers, OADM’s, Dispersion
compensators, OXC’s and electronic
regenerators
WDM Networks Evolution
•Second GenerationSecond Generation:: WDM networks with
ring and mesh architectures. These
systems are integrated with optical
amplifiers, OADM’s, Dispersion
compensators, OXC’s and electronic
regenerators
EAGLE PHOTONICS
WDM Networks Evolution
•Third GenerationThird Generation:: DWDM and OTDM
networks (All-optical networks )with linear,
ring and mesh architectures. These
systems are integrated with optical 3R
regeneration, OADM, OXC (which supports
Photonic packet switching)
WDM Networks Evolution
•Third GenerationThird Generation:: DWDM and OTDM
networks (All-optical networks )with linear,
ring and mesh architectures. These
systems are integrated with optical 3R
regeneration, OADM, OXC (which supports
Photonic packet switching)
EAGLE PHOTONICS
WDM Networks Evolution
WDM Networks Evolution
EAGLE PHOTONICS
1×40 G up to 65 km (Alcatel’98) PMD 1×40 G up to 65 km (Alcatel’98) PMD
Limited.Limited.
32× 5 G to 9300 km (1998)32× 5 G to 9300 km (1998)
64× 5 G to 7200 km (Lucent’97)64× 5 G to 7200 km (Lucent’97)
100×10 G to 400 km (Lucent’97)100×10 G to 400 km (Lucent’97)
16×10 G to 6000 km (1998)16×10 G to 6000 km (1998)
132×20 G to 120 km (NEC’96)132×20 G to 120 km (NEC’96)
70×20 G to 600 km (NTT’97)70×20 G to 600 km (NTT’97)
1022 Wavelengths on one fiber (Lucent 99)1022 Wavelengths on one fiber (Lucent 99)
Recent WDM RecordsRecent WDM Records
Source From Internet
1×40 G up to 65 km (Alcatel’98) PMD 1×40 G up to 65 km (Alcatel’98) PMD
Limited.Limited.
32× 5 G to 9300 km (1998)32× 5 G to 9300 km (1998)
64× 5 G to 7200 km (Lucent’97)64× 5 G to 7200 km (Lucent’97)
100×10 G to 400 km (Lucent’97)100×10 G to 400 km (Lucent’97)
16×10 G to 6000 km (1998)16×10 G to 6000 km (1998)
132×20 G to 120 km (NEC’96)132×20 G to 120 km (NEC’96)
70×20 G to 600 km (NTT’97)70×20 G to 600 km (NTT’97)
1022 Wavelengths on one fiber (Lucent 99)1022 Wavelengths on one fiber (Lucent 99)
Recent WDM RecordsRecent WDM Records
Source From Internet
EAGLE PHOTONICS
Max DWDM Throughput Achieved
•NEC :10.9 Tbps over a single fiber; 273 channels,
each at 40 Gbps over 117 km, Used S-band, C-
and L-bands for amplification; ultra-dense
channel multiplexing scheme (March 2002)
•Alcatel -- 256 wavelengths at 40 Gbps for 10.2
Tbps, March 2001
•Siemens/Optisphere -- 176 wavelengths at 40
Gbps for 7.04 Tbps, October 2000
Max DWDM Throughput Achieved
•NEC :10.9 Tbps over a single fiber; 273 channels,
each at 40 Gbps over 117 km, Used S-band, C-
and L-bands for amplification; ultra-dense
channel multiplexing scheme (March 2002)
•Alcatel -- 256 wavelengths at 40 Gbps for 10.2
Tbps, March 2001
•Siemens/Optisphere -- 176 wavelengths at 40
Gbps for 7.04 Tbps, October 2000
EAGLE PHOTONICS
DWDM Networks
DWDM Networks
EAGLE PHOTONICS
Post Amplifier Pre AmplifierLine Amplifier
Wavelengths Wavelengths
Optical Multiplexer Optical Demultiplexer
Linear Backbone LinkLinear Backbone Link
Post Amplifier Pre AmplifierLine Amplifier
Wavelengths Wavelengths
Optical Multiplexer Optical Demultiplexer
Linear Backbone LinkLinear Backbone Link
EAGLE PHOTONICS
Backbone Link With OADMBackbone Link With OADM
OADM
Mux Mux
DemuxDemux
Add Wavelengths
Drop Wavelengths
Backbone Link With OADMBackbone Link With OADM
OADM
Mux Mux
DemuxDemux
Add Wavelengths
Drop Wavelengths
EAGLE PHOTONICS
Optical Add/Drop MultiplexerOptical Add/Drop Multiplexer
Source From Internet
Optical Add/Drop MultiplexerOptical Add/Drop Multiplexer
Source From Internet
EAGLE PHOTONICS
Backbone Link With OXCBackbone Link With OXC
OXC
Mux Mux
DemuxDemux
Add/Drop Ports
Add/Drop Ports
Backbone Link With OXCBackbone Link With OXC
OXC
Mux Mux
DemuxDemux
Add/Drop Ports
Add/Drop Ports
EAGLE PHOTONICS
Optical Systems
Optical Systems
EAGLE PHOTONICS
WDM Systems
•3R Compensators
•Optical Amplifiers
•Optical Add/Drop Multiplexers
•Optical Cross Connects
WDM Systems
•3R Compensators
•Optical Amplifiers
•Optical Add/Drop Multiplexers
•Optical Cross Connects
EAGLE PHOTONICS
3R - Regeneration
3R regeneration means:
First R :Re-amplification
Second 2R: R + Re-shaping
Third 3R :2R + Re-timing
3R - Regeneration
3R regeneration means:
First R :Re-amplification
Second 2R: R + Re-shaping
Third 3R :2R + Re-timing
EAGLE PHOTONICS
3R Regenerators
These Regeneration done by
R- Done by Optical amplifiers
2R- Done by dispersion compensation or
OEO
3R- By using PLL and optical clock
recovery
3R Regenerators
These Regeneration done by
R- Done by Optical amplifiers
2R- Done by dispersion compensation or
OEO
3R- By using PLL and optical clock
recovery
EAGLE PHOTONICS
EAGLE PHOTONICS
Dispersion Compensation Modules
Dispersion Compensation Modules
EAGLE PHOTONICS
Purpose of DCM
•Dispersion is the function of the length of the
optical fiber and thus with respect of the length
it increases
•This accumulated dispersion lead to ISI and the
loss of the data in the transmission
•To overcome this accumulated dispersion and
increase the length of the transmission we need
a module called Dispersion Compensating
Module (DCM)
•DCM generally consist of optical elements
having high negative dispersion coefficient
Purpose of DCM
•Dispersion is the function of the length of the
optical fiber and thus with respect of the length
it increases
•This accumulated dispersion lead to ISI and the
loss of the data in the transmission
•To overcome this accumulated dispersion and
increase the length of the transmission we need
a module called Dispersion Compensating
Module (DCM)
•DCM generally consist of optical elements
having high negative dispersion coefficient
EAGLE PHOTONICS
Dispersion Compensation Module
DCM
with ILA
DCM with
Terminal
Dispersion Compensation Module
DCM
with ILA
DCM with
Terminal
EAGLE PHOTONICS
Dispersion Compensation
Methods
•The problem of dispersion-compensation
can be solved by one of way such as;
•Dispersion Compensating fiber (DCF)
•Chirped Fiber Bragg Grating
•Mid-span spectral inversion
•Multilevel coding
•First two approaches are more practical
and implemented in the field while last
two has only academic interests
Dispersion Compensation
Methods
•The problem of dispersion-compensation
can be solved by one of way such as;
•Dispersion Compensating fiber (DCF)
•Chirped Fiber Bragg Grating
•Mid-span spectral inversion
•Multilevel coding
•First two approaches are more practical
and implemented in the field while last
two has only academic interests
EAGLE PHOTONICS
Where DCM is Deployed?
DCM are deployed at various places in
the network
–After the transmitters
–With in Line amplifiers
–Before post amplifier
–After pre amplifier
Where DCM is Deployed?
DCM are deployed at various places in
the network
–After the transmitters
–With in Line amplifiers
–Before post amplifier
–After pre amplifier
EAGLE PHOTONICS
Optical Amplifier
Types of optical amplifiers
Principle of operation of
amplification
Amplifier vs. regenerators
Optical Amplifier
Types of optical amplifiers
Principle of operation of
amplification
Amplifier vs. regenerators
EAGLE PHOTONICS
Introduction
•In any link, optical power pumped and the
receiver sensitivity is limited and can only
support for a limited distance
•To over come the losses in the network, either
electrical or optical amplification is required
•Optical amplification is more cost effective
over electrical one
•An optical amplifier is a device which
amplifies the optical signal directly without
ever changing it to electricity
Introduction
•In any link, optical power pumped and the
receiver sensitivity is limited and can only
support for a limited distance
•To over come the losses in the network, either
electrical or optical amplification is required
•Optical amplification is more cost effective
over electrical one
•An optical amplifier is a device which
amplifies the optical signal directly without
ever changing it to electricity
EAGLE PHOTONICS
Types of Optical Amplifiers
Two Types of optical amplifiers available
•Solid state Optical Amplifiers
Semiconductor Optical Amplifiers
•Fiber Amplifiers
Erbium Doped Fiber Amplifiers ( EDFAs )
Raman Amplification ( RA )
Types of Optical Amplifiers
Two Types of optical amplifiers available
•Solid state Optical Amplifiers
Semiconductor Optical Amplifiers
•Fiber Amplifiers
Erbium Doped Fiber Amplifiers ( EDFAs )
Raman Amplification ( RA )
EAGLE PHOTONICS
Amplifiers in Transmission
Three type of fiber amplifier used in
transmission
•Pre Amplifier
•In-line Amplifier
•Post Amplifier
Amplifiers in Transmission
Three type of fiber amplifier used in
transmission
•Pre Amplifier
•In-line Amplifier
•Post Amplifier
EAGLE PHOTONICS
RxTx
S
i
g
n
a
l
P
o
w
e
r
Link Length
Receiver Sensitivity
Post Amplifier
Line Amplifier Pre Amplifier
Typical Point To Point Optical LinkTypical Point To Point Optical Link
RxTx
S
i
g
n
a
l
P
o
w
e
r
Link Length
Receiver Sensitivity
Post Amplifier
Line Amplifier Pre Amplifier
Typical Point To Point Optical LinkTypical Point To Point Optical Link
EAGLE PHOTONICS
In Line Amplifier
ILA
In Line Amplifier
ILA
EAGLE PHOTONICS
Pre and Post Amplifiers
•Post Amp is used to amplify the output of a
Multiplexer to a sufficient level to take care of the
link losses
•Preamp is used for amplifying the incoming signal
to a sufficient level for the detectors to sense the
signal
Pre and Post Amplifiers
•Post Amp is used to amplify the output of a
Multiplexer to a sufficient level to take care of the
link losses
•Preamp is used for amplifying the incoming signal
to a sufficient level for the detectors to sense the
signal
EAGLE PHOTONICS
Unidirectional versus Bi-directional
Terminal
ILA
Bidirectional
Coupler
Terminal
ILA
Bidirectional System
Unidirectional System
Unidirectional versus Bi-directional
Terminal
ILA
Bidirectional
Coupler
Terminal
ILA
Bidirectional System
Unidirectional System
EAGLE PHOTONICS
Erbium Doped Fiber Amplifiers
•An Erbium Doped Fibre Amplifier consists of a
short length of optical fibre doped by small
controlled amount of the rare earth element
erbium
•This rare earth element contributes in the
amplification process in presence of pump signal
•Pump laser excites erbium ions which give extra
energy to signal
•Principle of operation is similar to principle of a
laser
Erbium Doped Fiber Amplifiers
•An Erbium Doped Fibre Amplifier consists of a
short length of optical fibre doped by small
controlled amount of the rare earth element
erbium
•This rare earth element contributes in the
amplification process in presence of pump signal
•Pump laser excites erbium ions which give extra
energy to signal
•Principle of operation is similar to principle of a
laser
EAGLE PHOTONICS
EAGLE PHOTONICS
Configuration of EDFA
The typical configuration of the EDFA consists
of:
–Optical pump source
–WDM coupler
–Er
+
doped fiber
–Isolators
Configuration of EDFA
The typical configuration of the EDFA consists
of:
–Optical pump source
–WDM coupler
–Er
+
doped fiber
–Isolators
EAGLE PHOTONICS
Configuration of EDFA
Configuration of EDFA
EAGLE PHOTONICS
Erbium Doped Fiber Amplifier
•Pumping with 980nm laser is more effective
than 1480nm pumping
•Commonly used in submarine systems, and
increasingly on land
•Amplification possible at many wavelengths
around 1550nm
•Gain profile is not flat from the EDFA and
need some flatting mechanism
Erbium Doped Fiber Amplifier
•Pumping with 980nm laser is more effective
than 1480nm pumping
•Commonly used in submarine systems, and
increasingly on land
•Amplification possible at many wavelengths
around 1550nm
•Gain profile is not flat from the EDFA and
need some flatting mechanism
EAGLE PHOTONICS
Principle of EDFA Amplification
Principle of EDFA Amplification
EAGLE PHOTONICS
EAGLE PHOTONICS
Principle of Operation
•An optical amplification is done with the help of an
optical pump laser of selective wavelength
•Erbium ions are excited by the pump signal and
reached to the higher energy states
•Erbium ion at high-energy state will stimulated by
the signal needs amplification leads these ion
return to a lower-energy called ground energy state
•During this transition these ion emits a radiation of
similar to the signal
Principle of Operation
•An optical amplification is done with the help of an
optical pump laser of selective wavelength
•Erbium ions are excited by the pump signal and
reached to the higher energy states
•Erbium ion at high-energy state will stimulated by
the signal needs amplification leads these ion
return to a lower-energy called ground energy state
•During this transition these ion emits a radiation of
similar to the signal
EAGLE PHOTONICS
Amplification Profile
Amplification Profile
EAGLE PHOTONICS
Spectrum of a 32 Ch. DWDM
System
1528.77 nm 1562.23 nm
196.1 THz
191.9THz
Spectrum of a 32 Ch. DWDM
System
1528.77 nm 1562.23 nm
196.1 THz
191.9THz
EAGLE PHOTONICS
EAGLE PHOTONICS
C & L band of EDFAC & L band of EDFA
C & L band of EDFAC & L band of EDFA
EAGLE PHOTONICS
EAGLE PHOTONICS
Raman Fiber Amplifier
•Basic principle of Raman fiber amplifier is
Stimulated Raman Scattering (SRS)
•When stronger optical pump interacts with
the medium generates new signal (a Stokes
wave) in same direction
•New generated frequency is lesser then the
pump frequency by13.2 THz
•In normal fiber this effect is very small and it
takes a relatively long length to have
significant amplification
Raman Fiber Amplifier
•Basic principle of Raman fiber amplifier is
Stimulated Raman Scattering (SRS)
•When stronger optical pump interacts with
the medium generates new signal (a Stokes
wave) in same direction
•New generated frequency is lesser then the
pump frequency by13.2 THz
•In normal fiber this effect is very small and it
takes a relatively long length to have
significant amplification
EAGLE PHOTONICS
Raman Fiber Amplifier
•From this phenomenon signal of lower frequency
then pump gets amplified and the optimal
amplification occurs when the difference in
wavelengths is around 13.2 THz
•Any signal lower then pump can be amplified but
the efficiency will not be the same for all
•Efficiency can be improved by adding an FBG
(Fibre Bragg Grating) reflector for the pump
wavelength
•Thus any frequency can be generated from this
phenomenon
Raman Fiber Amplifier
•From this phenomenon signal of lower frequency
then pump gets amplified and the optimal
amplification occurs when the difference in
wavelengths is around 13.2 THz
•Any signal lower then pump can be amplified but
the efficiency will not be the same for all
•Efficiency can be improved by adding an FBG
(Fibre Bragg Grating) reflector for the pump
wavelength
•Thus any frequency can be generated from this
phenomenon
EAGLE PHOTONICS
Amplification in Different BandsAmplification in Different Bands
Amplification in Different BandsAmplification in Different Bands
EAGLE PHOTONICS
Amplifiers at Different Bands
TDFA: Thulium doped fiber amplifier
EDTFA:Erbium doped tellurite based fiber
amplifier
FRA: Fiber Raman amplifier
GS-EDFA:Gain shifted Erbium doped fiber
amplifier
Amplifiers at Different Bands
TDFA: Thulium doped fiber amplifier
EDTFA:Erbium doped tellurite based fiber
amplifier
FRA: Fiber Raman amplifier
GS-EDFA:Gain shifted Erbium doped fiber
amplifier
EAGLE PHOTONICS
Amplifier Vs. Repeaters
•Optical amplifier, amplifies an optical signal
without changing it to electrical signal
•Repeaters, Amplifies the optical signal after
converting back to electronics and generates
a new optical signal of the same format
•Reshaping & timing of data stream
Amplifier Vs. Repeaters
•Optical amplifier, amplifies an optical signal
without changing it to electrical signal
•Repeaters, Amplifies the optical signal after
converting back to electronics and generates
a new optical signal of the same format
•Reshaping & timing of data stream
EAGLE PHOTONICS
Amplification Vs. Regeneration
Amplification Vs. Regeneration
EAGLE PHOTONICS
Amplifier Vs. Repeaters Cont.
•Optical amplifiers are required typical after 30 to
100 km depends on the losses in the link
•Optical amplifier are very cost effective fo DWDM
systems
•Regenerations are typically necessary after about
600 km (at 2.5 Gbps)
•Regenerations operation become very cumbersome
for DWDM systems
Amplifier Vs. Repeaters Cont.
•Optical amplifiers are required typical after 30 to
100 km depends on the losses in the link
•Optical amplifier are very cost effective fo DWDM
systems
•Regenerations are typically necessary after about
600 km (at 2.5 Gbps)
•Regenerations operation become very cumbersome
for DWDM systems
EAGLE PHOTONICS
Optical Add/Drop Mux
Optical Add/Drop Mux
EAGLE PHOTONICS
Optical Add/Drop Mux
•System made of optical Mux & Demux components
•It selects the dropping wavelengths from the
incoming DWDM signals
•Adds the same wavelengths to the outgoing DWDM
signals
•It is a passive system and everything add/drop
wavelengths are fixed at the designing of this
system
Optical Add/Drop Mux
•System made of optical Mux & Demux components
•It selects the dropping wavelengths from the
incoming DWDM signals
•Adds the same wavelengths to the outgoing DWDM
signals
•It is a passive system and everything add/drop
wavelengths are fixed at the designing of this
system
EAGLE PHOTONICS
Optical Add Drop Multiplexer
OADM
OADM along
with ILA
without MSA
OADM
OADM along
with ILA
having MSA
Optical Add Drop Multiplexer
OADM
OADM along
with ILA
without MSA
OADM
OADM along
with ILA
having MSA
EAGLE PHOTONICS
Optical Add/Drop Mux
•Allows a few wavelengths to drop out of fiber
path, not all will need LTE equipment
•Useful at sites where a small number of
signals need to drop, not all wavelengths
Optical Add/Drop Mux
•Allows a few wavelengths to drop out of fiber
path, not all will need LTE equipment
•Useful at sites where a small number of
signals need to drop, not all wavelengths
EAGLE PHOTONICS
OADM EXAMPLE
ATM IP
Terminal OADM Terminal
Site Site Site
ATM
IP
OADM EXAMPLE
ATM IP
Terminal OADM Terminal
Site Site Site
ATM
IP
EAGLE PHOTONICS
Optical Cross Connects
Optical Cross Connects
EAGLE PHOTONICS
Optical Cross Connect
•It is consist of Optical Mux/Demux, Optical switch
•Required this device where multiple rings are
interconnection to each other
•Switching can be done in fiber, wavelength and
packet level
•Packet level switching is performed in electronics
domain
•Costly devices, but gives flexible networks can be
made intelligent networks
Optical Cross Connect
•It is consist of Optical Mux/Demux, Optical switch
•Required this device where multiple rings are
interconnection to each other
•Switching can be done in fiber, wavelength and
packet level
•Packet level switching is performed in electronics
domain
•Costly devices, but gives flexible networks can be
made intelligent networks
EAGLE PHOTONICS
Architecture of OXC
Architecture of OXC
EAGLE PHOTONICS
Hybrid SwitchingHybrid Switching
Source From Internet
Hybrid SwitchingHybrid Switching
Source From Internet
EAGLE PHOTONICS
DWDM Network Configuration
DWDM Network Configuration
EAGLE PHOTONICS
Typical DWDM Networks
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OADM OADM
T
e
r
m
i
n
a
l
OADM
OADM
OADM
Typical DWDM Networks
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OADM OADM
T
e
r
m
i
n
a
l
OADM
OADM
OADM
EAGLE PHOTONICS
Typical DWDM Networks
T
e
r
m
i
n
a
l
Termi
nal
Termi
nal
T
e
r
m
i
n
a
l
Regenera
tor
Site A
Site B
OA
DM
OA
DM
OA
DM
OA
DM
Typical DWDM Networks
T
e
r
m
i
n
a
l
Termi
nal
Termi
nal
T
e
r
m
i
n
a
l
Regenera
tor
Site A
Site B
OA
DM
OA
DM
OA
DM
OA
DM
EAGLE PHOTONICS
Cross Connecting DWDM
Networks
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OAD
OAD
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OXC
OADM OADM
OADM
OXC: Optical Cross Connect
Cross Connecting DWDM
Networks
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OAD
OAD
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OXC
OADM OADM
OADM
OXC: Optical Cross Connect
EAGLE PHOTONICS
Overlay of SONET over DWDM
T
e
r
m
i
n
a
l
OADM
OADM
ILA
OADM
OADM
SONET
ADM
SONET
ADM
SONET
ADM
SONET
ADM
Overlay of SONET over DWDM
T
e
r
m
i
n
a
l
OADM
OADM
ILA
OADM
OADM
SONET
ADM
SONET
ADM
SONET
ADM
SONET
ADM
EAGLE PHOTONICS
SONET
ADM
SONET
ADM
SONET
ADM
SONET
TM
T
e
r
m
i
n
a
l
Physical Ring, Logical Star
•Overlaying of Point-to-Multipoint SONET Network using one wavelength
for every link
•Route diverse protection could be implemented using extra wavelengths
•No reuse of wavelengths
•Underutilization of capacity
T
e
r
m
i
n
a
l
OADM
SONET
ADM
SONET
ADM
SONET
ADM
SONET
ADM
SONET
TM
T
e
r
m
i
n
a
l
Physical Ring, Logical Star
•Overlaying of Point-to-Multipoint SONET Network using one wavelength
for every link
•Route diverse protection could be implemented using extra wavelengths
•No reuse of wavelengths
•Underutilization of capacity
T
e
r
m
i
n
a
l
OADM
SONET
ADM
EAGLE PHOTONICS
Physical Ring, Logical Mesh
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OADM
SONET
ADM
SONET
ADMSONET
ADM
SONET
ADM
•Multiple SONET Rings are overlaid on the DWDM
Ring
•Reuse of wavelengths
•Optimum utilization of capacity
Physical Ring, Logical Mesh
T
e
r
m
i
n
a
l
T
e
r
m
i
n
a
l
OADM
SONET
ADM
SONET
ADMSONET
ADM
SONET
ADM
•Multiple SONET Rings are overlaid on the DWDM
Ring
•Reuse of wavelengths
•Optimum utilization of capacity
EAGLE PHOTONICS
Signal Velocity in Various MediaSignal Velocity in Various Media
Material
Propagation Velocity
(fraction of speed of
light in a vacuum)
Index of
refraction
Velocity of
signal (km/s)
Optical Fiber
Flint glass
Water
Diamond
Air
Copper Wire
(Category 5 cable)
.68
.58
.75
.41
.99971
.77
1.46
1.71
1.33
2.45
1.00029
N / A
205,000
175,000
226,000
122,000
299,890
231,000
Signal Velocity in Various MediaSignal Velocity in Various Media
Material
Propagation Velocity
(fraction of speed of
light in a vacuum)
Index of
refraction
Velocity of
signal (km/s)
Optical Fiber
Flint glass
Water
Diamond
Air
Copper Wire
(Category 5 cable)
.68
.58
.75
.41
.99971
.77
1.46
1.71
1.33
2.45
1.00029
N / A
205,000
175,000
226,000
122,000
299,890
231,000
EAGLE PHOTONICS
Chromatic Dispersion
•Optical Amplifiers does not correct the
dispersion of the fiber it only amplify the
optical pulses
Chromatic Dispersion
•Optical Amplifiers does not correct the
dispersion of the fiber it only amplify the
optical pulses
EAGLE PHOTONICS
Type of Chromatic Dispersion
•When velocity variation is caused by some
property of the wave guide materials - Effect
is called “Material Dispersion”
•When velocity variation is caused by structure
of the wave guide itself - Effect is called “Wave
guide Dispersion”
•When velocity variation is caused by refractive
index profile of the wave guide itself - Effect is
called “Profile Dispersion”
Type of Chromatic Dispersion
•When velocity variation is caused by some
property of the wave guide materials - Effect
is called “Material Dispersion”
•When velocity variation is caused by structure
of the wave guide itself - Effect is called “Wave
guide Dispersion”
•When velocity variation is caused by refractive
index profile of the wave guide itself - Effect is
called “Profile Dispersion”
EAGLE PHOTONICS
Chromatic Dispersion vs. Bit rate
Not significant
effect at OC-
48
Significant at
OC-192
Chromatic Dispersion vs. Bit rate
Not significant
effect at OC-
48
Significant at
OC-192
EAGLE PHOTONICS
Polarization Mode Dispersion
•Light traveling in single mode fiber vibrate in two
polarization states called modes, represents by x
and y axis of the optical fiber
•Two modes of polarization are at right angle (i.e.
orthogonal to each other)
•Refractive indices of the two polarization modes are
different due to imperfect circular symmetry of
optical fiber
Polarization Mode Dispersion
•Light traveling in single mode fiber vibrate in two
polarization states called modes, represents by x
and y axis of the optical fiber
•Two modes of polarization are at right angle (i.e.
orthogonal to each other)
•Refractive indices of the two polarization modes are
different due to imperfect circular symmetry of
optical fiber
EAGLE PHOTONICS
Polarization Mode Dispersion
•Difference in refractive indices lead to
variation in the velocity of these modes
through the fiber, causing a delay in time
domain
•This delay in time domain between the optical
pulses is known as polarization mode
dispersion (PMD)
•PMD is defined as this difference in arrival
times in pico-seconds, normalized to the
square root of the fiber length (ps/ Km)
Polarization Mode Dispersion
•Difference in refractive indices lead to
variation in the velocity of these modes
through the fiber, causing a delay in time
domain
•This delay in time domain between the optical
pulses is known as polarization mode
dispersion (PMD)
•PMD is defined as this difference in arrival
times in pico-seconds, normalized to the
square root of the fiber length (ps/ Km)
EAGLE PHOTONICS
Polarization Mode Dispersion
Polarization Mode Dispersion
EAGLE PHOTONICS
Non-Linear Effects
Non-Linear Effects
EAGLE PHOTONICS
Nonlinear Effects in Fiber
•Kerr Effects
–FWM
–SPM
–XPM
•Scattering effects
–Stimulated Raman Scattering
–Stimulated Brillouin Scattering
Nonlinear Effects in Fiber
•Kerr Effects
–FWM
–SPM
–XPM
•Scattering effects
–Stimulated Raman Scattering
–Stimulated Brillouin Scattering
EAGLE PHOTONICS
Non-linear Effects
Kerr Effects
Scattering Effects
Cross phase modulation
Four Wave Mixing
Self Phase Modulation
Stimulated Raman Scattering
Stimulated Brillouin Scattering
Non-linear Effects
Kerr Effects
Scattering Effects
Cross phase modulation
Four Wave Mixing
Self Phase Modulation
Stimulated Raman Scattering
Stimulated Brillouin Scattering
EAGLE PHOTONICS
Degradation Due to Non-linear Effects
Channel Spacing
Span LengthCapacity
Power Output
L
i
m
i
t
a
t
i
o
ns
Signal Losses
Noise
Cross Talk
Pulse broadening
L
i m
i t a
t i o
n
s
Degradation Due to Non-linear Effects
Channel Spacing
Span LengthCapacity
Power Output
L
i
m
i
t
a
t
i
o
ns
Signal Losses
Noise
Cross Talk
Pulse broadening
L
i m
i t a
t i o
n
s
EAGLE PHOTONICS
EAGLE PHOTONICS
FOUR WAVE MIXING
FOUR WAVE MIXING
EAGLE PHOTONICS
Four Wave Mixing
•Also known as four photon mixing
•Combination of three optical wave produced a new
optical wave
•The frequency of the new optical wave will be
f
FWM = f
1 + f
2 - f
3
•This effect dominates when the spacing of
channels are equal because the mixing products
can fall directly into other channel
•This increased the cross talk between the channels
Four Wave Mixing
•Also known as four photon mixing
•Combination of three optical wave produced a new
optical wave
•The frequency of the new optical wave will be
f
FWM = f
1 + f
2 - f
3
•This effect dominates when the spacing of
channels are equal because the mixing products
can fall directly into other channel
•This increased the cross talk between the channels
EAGLE PHOTONICS
Four Wave Mixing (FWM)
f
132f
312
f
321
f
113 f
112 f
123
f
213
f
223
f
221f
332
f
331
f
231
Optical
frequency
f
113
f
213
f
123
f
112
f
223
f
132
f
312
f
221
f
231
f
321
f
332
f
331
FWM optical power generated by three equally spaced signals
f1 f2 f3
Optical
frequency
FWM optical power generated by three unequally spaced signals
f1 f2 f3
Four Wave Mixing (FWM)
f
132f
312
f
321
f
113 f
112 f
123
f
213
f
223
f
221f
332
f
331
f
231
Optical
frequency
f
113
f
213
f
123
f
112
f
223
f
132
f
312
f
221
f
231
f
321
f
332
f
331
FWM optical power generated by three equally spaced signals
f1 f2 f3
Optical
frequency
FWM optical power generated by three unequally spaced signals
f1 f2 f3
EAGLE PHOTONICS
Stimulated Raman Scattering
Energy
Level
Time
SW Source
LW
Emission
Residue
Emission
Stimulated Raman Scattering
Energy
Level
Time
SW Source
LW
Emission
Residue
Emission
EAGLE PHOTONICS
Stimulated Raman Scattering (contd.)
•Short wavelength stimulates long wavelength
emission
•If the long wavelength emission falls within the
usable signal spectrum cross talk will occur
•Cross talk becomes significant when source
power crosses a threshold
•Example: In a 10 channel system with a channel
spacing of 1.3THz, the max power per channel is
3 mw
•In Raman amplification the short wavelength
source acts as a pump
Stimulated Raman Scattering (contd.)
•Short wavelength stimulates long wavelength
emission
•If the long wavelength emission falls within the
usable signal spectrum cross talk will occur
•Cross talk becomes significant when source
power crosses a threshold
•Example: In a 10 channel system with a channel
spacing of 1.3THz, the max power per channel is
3 mw
•In Raman amplification the short wavelength
source acts as a pump
EAGLE PHOTONICS
EAGLE PHOTONICS
Stimulated Brillouin Scattering (SBS)
•Similar to Raman Scattering, but stimulated
emission is in a lower wavelength
•SBS limits the total power that can be
injected into a single-mode fiber
•High capacity DWDM systems will have high
power output, which can lead to SBS
•Using special modulation of signal light, SBS
threshold can be raised
Stimulated Brillouin Scattering (SBS)
•Similar to Raman Scattering, but stimulated
emission is in a lower wavelength
•SBS limits the total power that can be
injected into a single-mode fiber
•High capacity DWDM systems will have high
power output, which can lead to SBS
•Using special modulation of signal light, SBS
threshold can be raised
EAGLE PHOTONICS
SPM: Self Phase Modulation
•Refractive index of fiber varies with intensity (Kerr
effect)
•Hence different intensity components of the
signal travels at different speeds, leading to
different phase delays for the components
•Phase delays cause signal distortion
•Predominant in G.652 and G.655 Fibers
•Maximum permitted channel power output will
depend on the span length, no. of spans etc.
SPM: Self Phase Modulation
•Refractive index of fiber varies with intensity (Kerr
effect)
•Hence different intensity components of the
signal travels at different speeds, leading to
different phase delays for the components
•Phase delays cause signal distortion
•Predominant in G.652 and G.655 Fibers
•Maximum permitted channel power output will
depend on the span length, no. of spans etc.
EAGLE PHOTONICS
EAGLE PHOTONICS
CPM: Cross Phase Modulation
•Occurs in DWDM systems when power fluctuations
of one signal result in distortion on other adjacent
channels
•Causes problems in systems with very narrow
channel spacing
•More dominant on G.652 fiber
•Maximum permitted channel power output will
depend on the span length, no. of spans etc. also
CPM: Cross Phase Modulation
•Occurs in DWDM systems when power fluctuations
of one signal result in distortion on other adjacent
channels
•Causes problems in systems with very narrow
channel spacing
•More dominant on G.652 fiber
•Maximum permitted channel power output will
depend on the span length, no. of spans etc. also
EAGLE PHOTONICS
EAGLE PHOTONICS
EAGLE PHOTONICS
EAGLE PHOTONICS
Tags
Categories
GeneralDownload
Download Slideshow Get the original presentation fileQuick Actions
Statistics
- Views 34
- Slides 132
- Age 434 days
Related Slideshows
22
Pray For The Peace Of Jerusalem and You Will Prosper
RodolfoMoralesMarcuc
35 views
26
Don_t_Waste_Your_Life_God.....powerpoint
chalobrido8
38 views
31
VILLASUR_FACTORS_TO_CONSIDER_IN_PLATING_SALAD_10-13.pdf
JaiJai148317
34 views
14
Fertility awareness methods for women in the society
Isaiah47
31 views
35
Chapter 5 Arithmetic Functions Computer Organisation and Architecture
RitikSharma297999
30 views
5
syakira bhasa inggris (1) (1).pptx.......
ourcommunity56
31 views