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Fiber Optics. Need for Fiber Optics technology is constantly increasingDriven by increasing data ratesDeclining implementation costMany advantagesExtremely High Data Carrying CapacityLow signal attenuationFree From Electromagnetic InterferenceLightweight. Presentation Overview. Technologies
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1. Fiber Optics For Broadcast Video ApplicationsEric FankhauserV.P. Advanced Product Development
2. Fiber Optics Need for Fiber Optics technology is constantly increasing
Driven by increasing data rates
Declining implementation cost
Many advantages
Extremely High Data Carrying Capacity
Low signal attenuation
Free From Electromagnetic Interference
Lightweight
3. Presentation Overview Technologies / Building blocks available
Lasers
Receivers
Fiber
Multiplexing
Switching
System Design Considerations
Application Examples
4. Technologies Available Transmitters (Light Sources)
LED’s - 850/1310nm
Used with MMF up to 250Mb/s
Short distances <1 Km
Semiconductor Lasers – 850/1310/1550nm
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)
5. FP and DFB Laser Spectrum FP laser
Emits multiple evenly spaced wavelengths
Spectral width = 4nm
DFB laser
Tuned cavity to limit output to single oscillation / wavelength
Spectral width = 0.1nm
6. Which Laser Type is Better? Fabry Perot
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 Distributed Feed Back
Used in wavelength division multiplexing systems
Less susceptible to dispersion than FP laser
Used for medium and long haul applications
7. Technologies Available Receivers (Detectors)
PIN Photodiodes
Silicon for shorter ?’s (eg 850nm)
InGaAs for longer ?’s (eg 1310/1550nm)
Good optical sensitivity
Avalanche Photodiodes (APD’s)
Up to 50% more sensitivity than PIN diodes
Primarily for extended distances in Gb/s rates
Much higher cost than PIN diodes
8. Multi-Mode
50/62.5um core, 125um clad
Atten-MHz/km: 200 MHz/km
Atten-dB/km: 3dB @ 850nm
MMF has an orange jacket
Single-Mode
9um core, 125um cladding
Atten-dB/km: 0.4/0.3dB 1310nm/1550nm
SMF has a yellow jacket
Fiber Types
9. Degradation In Fiber Optic Cable Attenuation
Loss of light power as the signal travels through optical cable
Dispersion
Spreading of signal pulses as they travel through optical cable
10. Attenuation Vs. Wavelength
11. Light Propagation 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
12. Bending Loss 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
13. Dispersion - Single-Mode 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)
14. Dispersion - Multi-Mode Fiber 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
15. Advances in Fiber Optic cable SMF
Reduction in the water peak
Reduction in loss per Km
Corning “SMF28e”
Lucent “AllWave”
MMF
Higher bandwidths
Most manu’s going to 50um, graded index fiber
16. Optimizing Fiber Usage Multiplexing
TDM – Time Division Multiplexing
WDM – Wave Division Multiplexing
17. Multiplexing - TDM 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
18. Multiplexing - TDM Latest developments in TDM
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
128 SDI per fiber (CWDM), 320 SDI per fiber (DWDM)
2 Ch HDSDI TDM mux
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
19. Wavelengths travel independently
Data rate and signal format on each wavelength is completely independent
Designed for SMF fiber Multiplexing - WDM
20. Multiplexing - WDM WDM – Wave Division Multiplexing
Earliest technology
Mux/Demux of two optical wavelengths (1310nm/1550nm)
Wide wavelength spacing means
Low cost, uncooled lasers can be used
Low cost, filters can be used
Limited usefulness due to low mux count
21. Multiplexing - DWDM DWDM – Dense Wave Division Multiplexing
Mux/Demux of narrowly spaced wavelengths
400 / 200 / 100 / 50 GHz Channel spacing
3.2 / 1.6 / 0.8 / 0.4 nm wavelength spacing
Up to 160 wavelengths per fiber
Narrow spacing = higher cost implementation
More expensive lasers and filters to separate ?’s
Primarily for Telco backbone – Distance
Means to add uncompressed Video signals to existing fiber
22. 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
23. CWDM Optical Spectrum 20nm spaced wavelengths
24. DWDM vs. CWDM Spectrum
25. Optical Routing - Definitions Optical Routers – Optical IN , Optical OUT
Photonic Routers – Optical IN & OUT but 100% photonic path
OOO- Optical to Optical to Optical switching
Optical switch fabric
OEO- Optical to Electrical to Optical conversion
Electrical switch fabric
Regenerative input and outputs
26. Photonic Technologies MEMS (Micro Electro-Mechanical System)
Liquid Crystal
MASS (Micro-Actuation and Sensing System )
27. MEMS Technology Steer the Mirror
Tilted mirrors shunt light in various directions
2D MEMS
Mirrors arrayed on a single level, or plane
Off or On state: Either deployed (on), not deployed (off)
3D MEMS
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)
28. Liquid Crystal Technology Gate the light
No Moving Parts
Slow switch speed
Small sizes (32x32)
Operation based on polarization:
One polarization component reflects off surfaces
Second polarization component transmits through surface
29. MASS Technology 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)
30. OEO Technology
31. OEO Routing Optical <> Electrical conversion at inputs/outputs
Provides optical gain (e.g. 23 dB)
High BW, rate agnostic electrical switching at core
SD, HD, Analog Video (digitized), RGBHV, DVI
Fast switching (<10us)
Full broadcast mode
One IN to ANY/Many outputs
Build-in EO / OE to interface with coax plant
Save converter costs
32. Regeneration - Optical vs Photonic Photonic is a lossy device that provide no re-amplification or regeneration
Signal coming in at –23dBm leaves at –25dBm
OEO router provides 2R or 3R (re-amplify, reclock, regenerate)
Signals come in at any level to –25dBm
Leave at –7dBm (1310nm) or 0dBm (CWDM)
33. Applications - Design Considerations Types of signals
Signal associations
Fiber infrastructure
Distance/Loss
Redundancy
Remote Monitoring
34. Types of Signals
35. Design Considerations Signal associations
Video, audio, data
Together or separate - Issues
Fiber infrastructure
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
Total path loss = (fiber+connectors+passives)
Distance can be deceiving - patches, connections, fusion splices
36. Design Considerations Fault Protection
Protection against fiber breaks
Important in CWDM and DWDM systems
Need 2:1 Auto-changeover function with “switching intelligence”
Measurement of optical power levels on fiber
Ability to set optical thresholds
Revert functions to control restoration
37. Remote monitoring is key due to distance issues
Monitor
Input signal presence and validity
Laser functionality and bias
Optical Link status and link errors
Pre-emptive Monitoring
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 Design Considerations
38. Diagnostics Interface
39. Design Examples – Single Link
40. Post House Facility link - Legacy
41. Post House Facility Link – New
42. Fiber STL
43. RF Over fiber optics -Applications
44. Large Video MAN – Fully protected
45. 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
46. QuestionsEric Fankhauserericf@evertz.comwww.evertz.com