Download A Fiber Optics Tutorial

Fiber Optics For Broadcast
Video Applications
Eric Fankhauser
V.P. Advanced Product Development
Fiber Optics

Need for Fiber Optics technology is
constantly increasing
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Driven by increasing data rates
Declining implementation cost
Many advantages
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Extremely High Data Carrying Capacity
Low signal attenuation
Free From Electromagnetic Interference
Lightweight
Presentation Overview
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Technologies / Building blocks available
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Lasers
Receivers
Fiber
Multiplexing
Switching
System Design Considerations
Application Examples
Technologies Available
Transmitters (Light Sources)
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LED’s - 850/1310nm
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Used with MMF up to 250Mb/s
Short distances <1 Km
Semiconductor Lasers – 850/1310/1550nm
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VCSEL’s, Fabry Perot and DFB
1310/1550 can be used with MMF or SMF
Short to long distances
Low to High data rates (Mb/s to Gb/s)
FP and DFB Laser Spectrum
FP Laser Output
DFB Laser Output
FWHM=4nm
Wavelength
(nm)
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FWHM=0.1nm
Wavelength
(nm)
FP laser
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Optical Output
Power (mW)
B
Optical Output
Power (mW)
A
Emits multiple evenly spaced wavelengths
Spectral width = 4nm
DFB laser
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Tuned cavity to limit output to single oscillation / wavelength
Spectral width = 0.1nm
Which Laser Type is Better?
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Fabry Perot
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Ideal for low cost pt-pt
MMF or SMF
Not suitable for WDM
due to +/- 30nm 
variation
Dispersion is a serious
issue at Gb/s rates
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Distributed Feed Back
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Used in wavelength
division multiplexing
systems
Less susceptible to
dispersion than FP laser
Used for medium and
long haul applications
Technologies Available
Receivers (Detectors)
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PIN Photodiodes
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Silicon for shorter ’s (eg 850nm)
InGaAs for longer ’s (eg 1310/1550nm)
Good optical sensitivity
Avalanche Photodiodes (APD’s)
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Up to 50% more sensitivity than PIN diodes
Primarily for extended distances in Gb/s rates
Much higher cost than PIN diodes
Fiber Types
Cladding
LED
Laser
Core
Cross section
Muliti Mode
Cladding
Core
Laser
Single Mode
Multi-Mode
Single-Mode
 50/62.5um core, 125um clad  9um core, 125um cladding
 Atten-MHz/km: 200 MHz/km  Atten-dB/km: 0.4/0.3dB
 Atten-dB/km: 3dB @ 850nm
1310nm/1550nm
 MMF has an orange jacket  SMF has a yellow jacket
Degradation In Fiber Optic Cable
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Attenuation
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Loss of light power as the signal travels
through optical cable
Dispersion
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Spreading of signal pulses as they travel
through optical cable
Attenuation Vs. Wavelength
Light Propagation
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Light propagates
due to total internal
reflection
Light > critical angle
will be confined to
the core
Light < critical angle
will be lost in the
cladding
Bending Loss
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Bends introduce an interruption in the
path of light causing some of the optical
power to leak into the cladding where it
is lost
Always keep a minimum bending radius
of 5cm on all corners
When bundling fibers with tie wraps
keep them loose to avoid introducing
micro bending into the fiber
Dispersion - Single-Mode
Receiver
Transmitter
Time
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FP and DFB lasers have finite spectral widths and
transmit multiple wavelengths
Different wavelengths travel at different speeds over fiber
A pulse of light spreads as it travels through an optical
fiber eventually overlapping the neighboring pulse
Narrower sources (e.g DFB vs. FP) yield less dispersion
Issue at high rates (>1Ghz) for longer distances (>50Km)
Dispersion - Multi-Mode Fiber
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Modal Dispersion
The larger the core of the fiber, the more
rays can propagate making the dispersion
more noticeable
Dispersion determines the distance a
signal can travel on a multi mode fiber
Advances in Fiber Optic cable
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SMF
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Reduction in the water peak
Reduction in loss per Km
Corning “SMF28e”
Lucent “AllWave”
MMF
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Higher bandwidths
Most manu’s going to 50um, graded index
fiber
Optimizing Fiber Usage
Multiplexing
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TDM – Time Division Multiplexing
WDM – Wave Division Multiplexing
Multiplexing - TDM
TDM
Multiplexed signal
Signal 1
Signal 2
Signal 3
Time
Division
Multiplex
Signal 1
Time
Division
De-multiplex
Signal 2
Signal 3
Single-mode Fiber
Signal 4
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Signal 4
Done in the electrical domain
Can TDM Video+Audio+Data OR Many
Video’s, Audio’s, Data’s
Increases efficiency of each wavelength
Max # of signals based on max link rate
Multiplexing - TDM
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Latest developments in TDM
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No synchronization required between signals – All
signals 100% independent
Low latency (<10us)
Small form factor (4/8 Ch in 1/2, 3RU card slot)
8 Ch SDI TDM mux
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2 Ch HDSDI TDM mux
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128 SDI per fiber (CWDM), 320 SDI per fiber (DWDM)
32 HD per fiber (CWDM), 80 HD per fiber (DWDM)
256 AES per fiber (CWDM), 640 AES (DWDM)
RGBHV over 1 fiber/1 wavelength vs 3 fibers
Multiplexing - WDM
WDM
Multiplexed signal
Signal 1
Signal 1
Signal 2
Signal 2
MUX
DEMUX
Signal 3
Signal 3
Single-mode Fiber
Signal 4
Signal 4
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Wavelengths travel independently
Data rate and signal format on each
wavelength is completely independent
Designed for SMF fiber
Multiplexing - WDM
WDM – Wave Division Multiplexing
 Earliest technology
 Mux/Demux of two optical wavelengths
(1310nm/1550nm)
 Wide wavelength spacing means
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Low cost, uncooled lasers can be used
Low cost, filters can be used
Limited usefulness due to low mux
count
Multiplexing - DWDM
DWDM – Dense Wave Division Multiplexing
 Mux/Demux of narrowly spaced wavelengths
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Up to 160 wavelengths per fiber
Narrow spacing = higher cost implementation
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400 / 200 / 100 / 50 GHz Channel spacing
3.2 / 1.6 / 0.8 / 0.4 nm wavelength spacing
More expensive lasers and filters to separate ’s
Primarily for Telco backbone – Distance
Means to add uncompressed Video signals to
existing fiber
Multiplexing - CWDM
CWDM – Coarse Wave Division Multiplexing
 Newest technology (ITU Std G.694.2)
 Based on DWDM but simpler and more robust
 Wider wavelength spacing (20 nm)
 Up to 18 wavelengths per fiber
 Uses un-cooled lasers and simpler filters
 Significant system cost savings over DWDM
 DWDM can be used with CWDM to increase
channel count or link budget
CWDM Optical Spectrum
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20nm spaced wavelengths
DWDM vs. CWDM Spectrum
1.6nm Spacing
dB
1470
1490
1510
1530
1550
1570
Wavelength
1590
1610
Optical Routing - Definitions
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Optical Routers – Optical IN , Optical OUT
Photonic Routers – Optical IN & OUT but
100% photonic path
OOO- Optical to Optical to Optical switching
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Optical switch fabric
OEO- Optical to Electrical to Optical
conversion
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Electrical switch fabric
Regenerative input and outputs
Photonic Technologies
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MEMS (Micro Electro-Mechanical System)
Liquid Crystal
MASS (Micro-Actuation and Sensing
System )
MEMS Technology
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Steer the Mirror
Tilted mirrors shunt light in various directions
2D MEMS
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3D MEMS
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Mirrors arrayed on a single level, or plane
Off or On state: Either deployed (on), not deployed (off)
Mirrors arrayed on two or more planes, allowing light to
be shaped in a broader range of ways
Fast switching speed (ns)
Photonic switch is 1:1 IN to OUT (i.e. no broadcast
mode)
Liquid Crystal Technology
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Gate the light
No Moving Parts
Slow switch speed
Small sizes (32x32)
Operation based on polarization:
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One polarization component reflects off
surfaces
Second polarization component transmits
through surface
MASS Technology
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Steer the fiber
Opto-mechanics uses piezoelectric actuators
Same technology as Hard Disk Readers and
Ink Jet Printer Heads
Small-scale opt mechanics: no sliding parts
Longer switch time (<10msec)
OEO Technology
Fiber
Inputs
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
Electrical
Inputs
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
High BW
Electrical
XPNT
Fiber
Outputs
X
Electrical
Outputs
Monitoring
Interface
CPU
Local
Indication
OEO Routing
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Optical <> Electrical conversion at inputs/outputs
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High BW, rate agnostic electrical switching at core
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SD, HD, Analog Video (digitized), RGBHV, DVI
Fast switching (<10us)
Full broadcast mode
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Provides optical gain (e.g. 23 dB)
One IN to ANY/Many outputs
Build-in EO / OE to interface with coax plant
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Save converter costs
Regeneration - Optical vs Photonic
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Photonic is a lossy device that provide no
re-amplification or regeneration
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Signal coming in at –23dBm leaves at –
25dBm
OEO router provides 2R or 3R (re-amplify,
reclock, regenerate)
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Signals come in at any level to –25dBm
Leave at –7dBm (1310nm) or 0dBm (CWDM)
Applications - Design Considerations
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Types of signals
Signal associations
Fiber infrastructure
Distance/Loss
Redundancy
Remote Monitoring
Types of Signals
FacilityLINK - Fiber Optics Platform
VIDEO
AUDIO
MULTI
WAVELENGTH OR
SDI
HDSDI
ANALOG
DVB-ASI
RGB
MULTI
FIBER
AES
ANALOG
DOLBY E
INTERCOM
OPTICAL
CONTROL
DATACOM
RF
TELECOM
WDM
CWDM
DWDM
RS232/422/485
GPI/GPO
10/100 ETHERNET
GBE
FIBER CHANNEL
70/140 MHz I/F
L-BAND
CATV
SONET OC3/12
T1/E1
DS3/E3
ROUTING
SPLITTERS
+
PROTECTION
SWITCHING
Design Considerations
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Signal associations
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Fiber infrastructure
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Video, audio, data
Together or separate - Issues
MMFor SMF
Many fibers or one fiber
Single clean run for your use (e.g. put in for you)
Leased fiber (multiple patches, fusion splices)
Distance/Loss
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Total path loss = (fiber+connectors+passives)
Distance can be deceiving - patches, connections,
fusion splices
Design Considerations
Fault Protection
 Protection against fiber breaks
 Important in CWDM and DWDM systems
 Need 2:1 Auto-changeover function with
“switching intelligence”
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Measurement of optical power levels on fiber
Ability to set optical thresholds
Revert functions to control restoration
Design Considerations
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Remote monitoring is key due to distance issues
Monitor
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Input signal presence and validity
Laser functionality and bias
Optical Link status and link errors
Pre-emptive Monitoring
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Input cable equalization level
CRC errors on coax or fiber interface
Optical power monitoring
Data logging of all error’d events
Error tracking and acknowledgment
Diagnostics Interface
Design Examples – Single Link
-7dBm @ 1310nm
SDI @
270Mb/s
SD EO
-32dBm
40 Km’s
-7dBm @ 1310nm
HDSDI @
1.485Gb/s
HD EO
Loss Budget
SD
-23dBm
40 Km’s
SDI @
270Mb/s
SD OE
HD OE
HDSDI @
1.485Gb/s
Dispersion
HD
HD
FP
DFB
SD
HD
HD
FP
DFP
TX Power (dBm)
-7
-7
0
FP Line width (nm)
4
4
0.2
RX Sens (dBm)
-32
-23
-23
Dispersion (ps/nm.km)
2
2
2
Available Budget
25
16
23
Distance (km)
40
40
40
Distance (Km)
40
40
40
Dispersion (ps)
320
320
16
Fiber Loss
(0.35dB/km@1310)
14
14
14
RX Jitter Tolerance (UI)
0.4
0.4
0.4
RX Jitter Tolerance (ps)
1480
270
270
Connectors
4
4
4
Headroom (ps)
1160
-50
254
Connector Loss
1
1
1
Total Loss
15
15
15
Headroom
10
1
8
Post House Facility link - Legacy
Location #2
Location #1
SDI @
270Mb/s
1510
1310
HDSDI @
1.485Gb/s
SONET OC3
@155Mb/s
1510
E to O
1530
1530
E to O
ATM
Switch
1310
HDSDI @
1.485Gb/s
O to E
CWDM M4
1550
CWDM D4
1550
2 Km’s
O to O
ATM
Switch
1570
1310
HIPPI @
SDI @
270Mb/s
O to E
SONET OC3
@155Mb/s
HIPPI @
1570
O to O
1.2Gb/s
1.2Gb/s
1510
SDI @
270Mb/s
O to E
HDSDI @
1.485Gb/s
O to E
1510
1530
SONET OC3
@155Mb/s
HDSDI @
1.485Gb/s
1530
E to O
CWDM D4
CWDM M4
1550
WDM
1550
WDM
1310
ATM
Switch
O to O
ATM
Switch
1570
HIPPI @
SDI @
270Mb/s
1310
E to O
1570
1310
HIPPI @
O to O
1.2Gb/s
RS422
1310
E to O
1310
O to E
SONET OC3
@155Mb/s
1.2Gb/s
RS422
Post House Facility Link – New
Location #2
Location #1
SDI @
270Mb/s
1310
HDSDI @
1.485Gb/s
E to O
O to E
O to E
E to O
E to O
O to E
O to E
E to O
HDSDI @
1.485Gb/s
Analog Video
Mux + EO
Demux+OE
Analog Video
Analog Audio
OE+Demux
EO + Mux
Analog Audio
Demux+OE
Analog Video
EO + Mux
Analog Audio
Analog Video
Mux + EO
Analog Audio
OE+Demux
CWDM
M16
GBE
10/100 Mb/s
Ethernet
RS422
AES
SDI @
270Mb/s
2 Km’s
CWDM
D16
Gbe
Gbe
10/100
10/100
10/100 Mb/s
Ethernet
RS422
RS422
RS422
Mux +EO
Demux +OE
Demux +OE
Mux + EO
GBE
AES
Fiber STL
BROADCAST CENTER
6 AES
Audio
for
Radio
Coax to Fiber
Coax to Fiber
Coax to Fiber
Fiber to Coax
NTSC Enc
Fiber to Coax
NTSC Enc
Fiber to Coax
NTSC Enc
Fiber to Coax
NTSC Enc
CH 2
CH 3
CH 4
Audio Demux
SDI
Video
with
Embedd
ed Audio
CH 1
Monitoring
Points
Audio Mux
Coax to Fiber
CN TOWER
Cat 5 to Fiber
X
Fiber to Cat 5
6 AES
Audio
for
Radio
Analog
Video
and
Audio
Monitorin
g and
Control
RF Over fiber optics -Applications
Typical Satellite Application With SNMP Monitoring
L-Band Downlink (950Mhz – 2250Mhz)
Vertical
LB EO
BPX-RF
LB OE
DA8-RF
Router
Horizontal
BPX-RF
LB EO
LB OE
Ethernet
/ SNMP
Remote
Ethernet
SNMP
/ SNMP Monitoring
& Control
LNB
Power
Ethernet
/ SNMP
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
HPA
C or Ku
Up Conv
IF OE
IF EO
IF Uplink (70/140Mhz)
DA-RF
Video Mod
DA-RF
Video Mod
BPX-RF
Large Video MAN – Fully protected
VideoMan Nodes Layout
KRCA
KNBC
KABC
2.3
Circle seven 7.3
KVEA
2.9
2.3
5.75
LA Zoo
2.3
Extra
KABC
Prospect
RSE
25 mi
25 mi
KCBS
KTLA
TV
Gaming
Fox
Sports
KSCI
Ent ..
Tonight
Fox
7.25
CNN
1.1
1.1
1.5
9 Net
Australia
1.1
2.7
2.1
CBS
VYVX
Fiber
4 mi
Dodger
Stadium
11 mi
1.5
0
2.5
Intelsat
RSH
RSK
0.5
5.5 mi
0.5
8 mi
8 mi
9.8 mi
5.5 mi
0.5
One
Wilshire
6.2
7.5
KTTV
E!
0.8
NCTC
7.25
Pac TV
0.7
KMEX
Japan
Telecom
0.75
Globesat
10.5
Direct
TV
13.5 mi
10.5
BT
DT
11/17/03
Summary
Fiber is an ideal transport medium
 No magic involved in using fiber
optics
 Many solution options available
 Proper upfront system design
upfront prevents many headaches

Questions
Eric Fankhauser
[email protected]
www.evertz.com