EE 230: Optical Fiber Communication Lecture 16 From the movie Warriors of the Net Active WDM Components and Networks

Optical Switches

Optical Switching Matrix

Switching methods Thermo-optic Tunable filters Liquid crystal Electro-optic Liquid reflection MEMS

Tunable Optical Filters

Agilent Bubble Switch

MEMS Technology

Wavelength Converters

OADM Illustrated OADM Sites nm nm nm nm Optical Fiber

OADM Illustrated OADM Sites nm nm nm nm Optical Fiber

OADM Illustrated OADM Sites nm nm nm nm Optical Fiber

OADM Illustrated OADM Sites nm nm nm nm Optical Fiber

OADM Illustrated OADM Sites nm nm nm nm Optical Fiber

OADM Illustrated OADM Sites nm nm nm nm Optical Fiber

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

MEMS OXC in Action (MEMX Co.)

Spectral Efficiency of WDM Systems For  =100 GHz and B=10 Gb/s,  =10% For  =50 GHz and B=40 Gb/s,  =80%

Transport Fiber SONET Add/Drop Mux Digital Crossconnect WDM Transport Equipment Add/Drop Channels 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 Typical Network Structure

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 0 km 16 km 25 km 41 km

OC-48 Eye Diagrams BERT Laser Input Laser Output Receiver Module Output Regenerated Data (CDR output) CDR Input

10Gb/s Eye vs. Transmission Distance Optical SignalInput to CDR Optical Signal Input to CDR 0 km 12 km 16 km 25 km 37 km 41 km

OC-192 Link Testing Eye Diagrams throughout the system Input Signal from BERT After Laser Driver Optical Signal from Laser After Receiver Module Input to CDR Regenerated Data

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 Advantages 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 The Future?

Design Objective 120 Gb/s Optical WDM Cross Connect Switch 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 W DM with E lectronic S witching T echnology 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) Advantages of an Electronic Core

WEST System Demonstration Configuration 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

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 mm transistors P diss : 7.4 W 10Gb/s 12x12 VXI Switch Module Feature Highlights

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)