EE 230: Optical Fiber Communication Lecture 10

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

2. 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

3. 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

4. Three Hottest Trends in DigitalHome Communications Terminals 1. DVR 2. HDTV 3. xOD

5. 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

6. 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.

7. Bandwidth Comparisons

8. 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?

9. Laser Diode Transmitter Block Diagram

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

11. Step and Graded Index Fiber Coupling

12. Graded Index Fiber Coupling Continued

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

14. Turn-on delay

15. 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

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

17. B i a s A d j u s t M o n i t o r P h o t o d i o d e M o n i t o r P h o t o d i o d e L a s e r L a s e r - - - -5V B i a s V r e f V r e f A v e r a g e + + P o w e r + I n t e g r a t o r D a t a D a t a M o d u l a t e d P o w e r A d j u s t D a t a D a t a - - -5V - + M o d u l a t i o n + -5V P e a k - p e a + I n t e g r a t o r -5V P o w e r P e a k D e t e c t o r 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

18. 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 • BER<10-14 • 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

19. Example Commercial Transmitter Module Palomar Technologies

20. 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 • Demonstrated link operation over 29 km • at 5 Gb/s Lo et. al. IEEE Photonics Technology Letters, Vol. 2, No. 9, September 1990

21. Polarization • In molecules, P=μ+αE+βE2+γE3+… • In materials, P=X(o)+X(1)E+X(2)E2+X(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.

22. Electro-Optic Coefficient r