EE 230: Optical Fiber Communication Lecture 10

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EE 230 Optical Fiber Communication Lecture 10
Special Broadband to the User Presentation
Transmitters
From the movie Warriors of the Net
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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
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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 2010.
• Our job catalyzing innovation

California has the most to gain from action and
the most to lose by inaction. The Gartner Report
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Three Hottest Trends in DigitalHome
Communications Terminals

• 1. DVR

2. HDTV
3. xOD
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The Services of Tomorrow

• Enable Advanced Services

Replacement Services
Visionary Services and Capabilities
Internet
Movies-on-Demand
Distance Learning
Broadcast TV
Time-Shifted TV
Telemedicine
Internet Telephony
Notification Services
Multiplayer Gaming
Community Intranet
Videoconferencing
Power Metering
Security Video
Home Automation
Voice Response
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Next Generation Broadband

• Its not about capacity. Its 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.

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Bandwidth Comparisons
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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 doesnt
  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?

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Laser Diode Transmitter Block Diagram
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Source-Fiber Coupling Lambertian Sources
Lambertian Source radiance distribution
Generalized Coupled Power
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Step and Graded Index Fiber Coupling
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Graded Index Fiber Coupling Continued
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Source Fiber Coupling - II
Schematic of a typical assembly of coupling optics
Transmitters employing a) butt-coupling and b)
lens-coupling designs
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Turn-on delay
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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
r0 if the optical signal is completely
extinguished during a logical 0 r1 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
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Traditional Laser Transmitter Approaches
Use a transmission line and impedance match
Keep it close and dont worry about the match
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Laser Driver Stabilization
Average Power and Mark Density Compensation
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
Average and Peak Power Stabilization
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Packaging
Drawing of Packaging Approach
Optical Module (a), Electrical module (b)

• 10 Channels
• 12.5 Gb/s aggregate bandwidth
• 1300 nm commercial laser array
• 50/125 Multimode fiber ribbon
• 130 mW/channel
• CMOS Driver Array
• BERlt10-14
• 1.2 km transmission with no
• BER degradation

Close-up of assembled module
Completed module integrated on test board
Bostica et. al., IEEE Transactions on Advanced
Packaging, Vol. 22, No 3, August 1999
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Example Commercial Transmitter Module
Palomar Technologies
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DFB-HEMT OEIC Laser Transmitter

• Transistor Technology
• InGaAs-InAlAs HEMT
• 1.5 mm 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
• l/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

Lo et. al. IEEE Photonics Technology Letters,
Vol. 2, No. 9, September 1990
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Polarization

• In molecules, PµaEßE2?E3
• In materials, PX(o)X(1)EX(2)E2X(3)E3
• 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.

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Electro-Optic Coefficient r