EE 230: Optical Fiber Communication Lecture 10 From the movie Warriors of the Net Special Broadband to the User Presentation Transmitters

First Mile: Bringing the Broadband Infrastructure Home  Fred Cohn, City of Monterey  Dick DeWees, City of Lompoc  Susan Estrada, CENIC  Seth Fearey, Connected Communities  Bryan Wassom, Alcatel League of California Cities Planners Institute March 31, 2004 Monterey, CA League of California Cities Planners Institute March 31, 2004 Monterey, CA

The One Gigabit or Bust ™ Initiative > The Mission Establish an action plan that will bring one gigabit to every home, business, and school in California by Our job = catalyzing innovation California has the most to gain from action and the most to lose by inaction. — The Gartner Report

Three Hottest Trends in Digital Home Communications Terminals 1. DVR 2. HDTV 3. xOD

The Services of Tomorrow Enable Advanced Services Internet Broadcast TV Internet Telephony Power Metering Movies-on-Demand Time-Shifted TV Notification Services Videoconferencing Security Video Distance Learning Telemedicine Multiplayer Gaming Community Intranet Home Automation Replacement ServicesVisionary Services and Capabilities Voice Response

Next Generation Broadband > “It’s not about capacity. It’s about the capabilities made available by the capacity.” Nitin Shaw, Arraycom > Historical evolution of bandwidth requirements support one gigabit per second by 2010 > We need the big red circle.

Bandwidth Comparisons

Broadband and Economic Development > Broadband equals J-O-B-S Gartner study said 2 million new jobs in California > “No business will settle in a town that doesn’t have broadband access.” NYT, 3/24/04 > Question: What had made your communities think about installing next generation broadband? Are you losing jobs? Do you think broadband helps with business development?

Laser Diode Transmitter Block Diagram

Source-Fiber Coupling – Lambertian Sources Generalized Coupled Power Lambertian Source radiance distribution

Step and Graded Index Fiber Coupling

Graded Index Fiber Coupling Continued

Source Fiber Coupling - II Schematic of a typical assembly of coupling optics Transmitters employing a) butt-coupling and b) lens-coupling designs

Turn-on delay

Extinction Ratio Penalty If the transmitter does not turn all the way “off” during the transmission of a “zero” then the extinction ratio r ( the ratio to a power transmitted during a “0” to that during a “1”) will cause a bit error rate penalty and a reduction in sensitivity. For a PIN receiver the peak power required for a given signal to noise ratio will become: r=0 if the optical signal is completely extinguished during a logical “0” r=1 if the optical power during a “0” equals that during a “1” in this case the power required approaches  For APD detectors with gain the effect of the multiplied noise during the “0” is more severe, this case is shown in the graph to the left. k is the ratio of the hole and electron ionization coefficients and is a property of the material in the avalanche multiplication region

Traditional Laser Transmitter Approaches Use a transmission line and impedance match Keep it close and don’t worry about the match

Laser Driver Stabilization Average Power and Mark Density Compensation Average and Peak Power Stabilization Average Power, Mark Density and Modulation A variety of feedback approaches are available to compensate for laser imperfections and the consequences of temperature variation and aging

Packaging Bostica et. al., IEEE Transactions on Advanced Packaging, Vol. 22, No 3, August 1999 Drawing of Packaging Approach Optical Module (a), Electrical module (b) Close-up of assembled module Completed module integrated on test board 10 Channels 12.5 Gb/s aggregate bandwidth 1300 nm commercial laser array 50/125 Multimode fiber ribbon 130 mW/channel CMOS Driver Array BER< km transmission with no BER degradation

Example Commercial Transmitter Module Palomar Technologies

DFB-HEMT OEIC Laser Transmitter Transistor Technology InGaAs-InAlAs HEMT 1.5  m gate length Laser Distributed Feedback Laser Self-Aligned Constricted Mesa (SACM) 7 MHz linewidth at 3 mW output power 19 GHz –3db frequency 8 mA average threshold Fabrication /4 shifted cavity fabricated by e-beam 2-step MOCVD OEIC Performance: Clean output eyes for all pattern lengths up to 5 Gb/s Operation at shorter patterns up to 10 Gb/s Demonstrated link operation over 29 km at 5 Gb/s Lo et. al. IEEE Photonics Technology Letters, Vol. 2, No. 9, September 1990

Polarization > In molecules, P=μ+αE+βE 2 +γE 3 +… > In materials, P=X (o) +X (1) E+X (2) E 2 +X (3) E 3 +… If multiple electric fields are applied, every possible cross term is generated. At sufficiently high values of E, quadratic or higher terms become important and nonlinear effects are induced in the fiber.

Electro-Optic Coefficient r