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EE 230: Optical Fiber Communication Lecture 16. Active WDM Components and Networks. From the movie Warriors of the Net. Optical Switches. Optical Switching Matrix. Switching methods. Thermo-optic Tunable filters Liquid crystal Electro-optic Liquid reflection MEMS.
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EE 230: Optical Fiber Communication Lecture 16 Active WDM Components and Networks From the movie Warriors of the Net
Switching methods • Thermo-optic • Tunable filters • Liquid crystal • Electro-optic • Liquid reflection • MEMS
OADM Illustrated Optical Fiber 1557.36nm 1555.75nm OADM Sites 1535.04nm 1533.47nm
OADM Illustrated Optical Fiber 1557.36nm 1555.75nm OADM Sites 1535.04nm 1533.47nm
OADM Illustrated Optical Fiber 1557.36nm 1555.75nm OADM Sites 1535.04nm 1533.47nm
OADM Illustrated Optical Fiber 1557.36nm 1555.75nm OADM Sites 1535.04nm 1533.47nm
OADM Illustrated Optical Fiber 1557.36nm 1555.75nm OADM Sites 1535.04nm 1533.47nm
OADM Illustrated Optical Fiber 1557.36nm 1555.75nm OADM Sites 1535.04nm 1533.47nm
Opaque vs. Transparent OXCs • Opaque: every wavelength undergoes OEO conversion. S/N degradation does not accumulate, simple route choice, can change wavelengths at each hop, simple network management • Transparent: all-optical. Less expensive, dissipates less power, fewer interfaces, no electronics limit on bit rate. Works better in ring networks
Spectral Efficiency of WDM Systems For =100 GHz and B=10 Gb/s, =10% For =50 GHz and B=40 Gb/s, =80%
Typical Network Structure • Composed of WDM Transport Equipment SONET ADD/Drop Muxes Digital Crossconnect • Advantages Off the shelf technology Full SONET Management and QOS Flexible routing at STS-1 or below • Disadvantages Large Expensive Diversity of management systems Difficult Provisioning Expensive interconnect cabling Digital Crossconnect Transport Fiber WDM Transport Equipment SONET Add/Drop Mux Add/Drop Channels
Types of WDM Networks • Local area (LAN) • Metropolitan area (MAN) • Wide area (WAN)
Configurations of WDM Networks • star—good for LANs • bus (chain)--LANs • ring—good for MANs and WANs • hub—good for WANs; collection of stars or rings
Limitations on Performance, N • Wavelength stability of diode lasers • Nonlinear optical effects • Crosstalk in the demultiplexing process
OC-48 Link Performance vs. Distance 16 km 25 km 0 km 41 km
OC-48 Eye Diagrams Receiver Module Output BERT Laser Input CDR Input Laser Output Regenerated Data (CDR output)
10Gb/s Eye vs. Transmission Distance Optical Signal Input to CDR Optical Signal Input to CDR 25 km 0 km 12 km 37 km 16 km 41 km
OC-192 Link TestingEye Diagrams throughout the system After Receiver Module Input Signal from BERT Input to CDR After Laser Driver Regenerated Data Optical Signal from Laser
The Future? Advantages •Reduced Cost •More Compact •Lower Power •Rapid physical layer protection switching Simplified Operation, Administration, Management and Provisioning •Simpler Network interface •Fewer different management systems •Leverages traditional link based management and protection Disadvantages • No low level traffic grooming • Not directly compatible with SONET protection protocols • Less bandwidth efficient • No “statistical multiplexing” of low level STS-n data streams
Design Objective120 Gb/s Optical WDM Cross Connect Switch WDM with Electronic Switching Technology • Cross Connect Configuration • 3x3 fiber switch • 4 channels/fiber • 10 Gb/s/channel • Electronic Switch Core • OC192/OC48 compatible • Optical MUX/DEMUX • ITU WDM channels • Key Technology • Rockwell GaAs HBT • Ortel DFB Laser/PIN Advantages of an Electronic Core • Data regeneration/retiming • Wavelength translation • Low crosstalk • OC192/OC48 compatible • Realizable with current state-of-the-art production technology • Potential for additional processing of input signal (smart switch)
WEST System DemonstrationConfiguration Overview • Configured as an Add/Drop node • 4 Channels of Add/Drop • 8 Transmission Channels • Optical Monitoring • Eye diagram monitoring • Clock monitoring for acquisition • demonstration
12x12 VXI Switch ModuleFeature Highlights • Switch Module Features: • 120 Gb/s data throughput • Twelve 10 Gb/s channels • VXI Management and Control • High Speed Package Features: • Clean high speed interface • High Isolation • Thermal management • Switch Chip Highlights: • Suitable for larger switching fabrics • GaAs/AlGaAs HBT • Low crosstalk & jitter generation • Die size: 4.8 x 5.1 mm2 • 4600 transistors • Pdiss: 7.4 W 10Gb/s
WDM Network Design Considerations • transparent or opaque? • power level? (high better for receivers, low better for transmitters and NLO) • branching configuration? • channel spacing? (small better for capacity, large better for crosstalk)