Optical Communications: Circuits, Systems and Devices

1. Optical Communications: Circuits, Systems and Devices Chapter 1: IntroductionOptical Fiber Communication: Technology and Systems Overviewlecturer: Dr. Ali Fotowat Ahmady September, 2012 Sharif University of Technology

2. Chapter 1 Introduction Optical Fiber Communications High Speed Electrical Links• Necessary to equalize the growing disparity between on-chip computation and chip-to-chip communication bandwidth• Components - High-bandwidth transceiver (TX, RX) - Terminated channel - Precise clock generation and recovery Sharif University of Technology

3. Chapter 1 Introduction Optical Fiber Communications Limitations of Electrical Links (1 of 2) • Maximum on-chip clock frequency that can be propagated without swing attenuation• Clock period limit  6 – 8 FO4 inverter delays - 0.25 CMOS  750 – 1000ps  1 – 1.3GHz Sharif University of Technology

4. Chapter 1 Introduction Optical Fiber Communications Limitations of Electrical Links (2 of 2) • Limited bandwidth distance product of wires Bits/s (LC lines)• Proportional noise sources - Reflections - Cross-talk• Power Consumption ~ 30mW/Gb/s Sharif University of Technology

5. Chapter 1 Introduction Optical Fiber Communications Electromagnetic Spectrum Sharif University of Technology

6. Chapter 1 Introduction Optical Fiber Communications Benefits of Optical Links (1 of 2) • Enormous capacity: 1.3 mm-1.55 mm allocates bandwidth of 37 THz!!• Cables and equipment have small size and weight - A large number of fibers fit easily into an optical cable - Applications in special environments as in aircrafts, satellites, ships • Longer Distances (SMF) - Less attenuation per distance: Optical fiber loss can be as low as 0.2dB/km Compared to loss of coaxial cables: 10-300dB/km) - Almost zero frequency dependant loss - Dispersion Limited (Chromatic ~5ps/nm/km)• Lower Power - Less attenuation Sharif University of Technology

7. Chapter 1 Introduction Optical Fiber Communications Benefits of Optical Links (2 of 2) • Less Noise - No crosstalk between fibers - No reflections• Immunity to interference - Nuclear power plants, hospitals, EMP resistive systems (installations for defense)• Electrical isolation - Electrical hazardous environments - Negligible crosstalk• Signal security - Banking, computer networks, military systems• Silica fibers have abundant raw material Sharif University of Technology

8. Chapter 1 Introduction Optical Fiber Communications Market Transition from Electrical to Optical Sharif University of Technology

9. Chapter 1 Introduction Optical Fiber Communications History of Optical Telecommunications (1 of 3)• Roman times-glass drawn into fibers• Venice Decorative Flowers made of glass fibers• 1841- Daniel Colladon-Light guiding demonstrated in water jet• 1870- Tyndall observes light guiding in a thin water jet• 1880- Bell invents Photophone• 1888- Hertz Confirms EM waves and relation to light• 1880-1920 Glass rods used for illumination• 1930- Lamb experiments with silica fiber• 1931- Owens-Fiberglass• 1951- Heel, Hopkins, Kapany image transmission using fiber bundles• 1958- Goubau et. al. Experiments with the lens guide• 1958-59 Kapany creates optical fiber with cladding Sharif University of Technology

10. Chapter 1 Introduction Optical Fiber Communications History of Optical Telecommunications (2 of 3) • 1960- Ted Maiman demonstrates first laser in Ruby• 1960- Javan et. al. invents HeNe laser• 1962- 4 Groups simultaneously make first semiconductor lasers• 1961-66 Kao, Snitzer et al conceive of low loss single mode fiber communications and develop theory• 1970- First room temp. CW semiconductor laser-Hayashi & Panish• 1975- Coax, 274 Mb/s at 1km repeater spacing• April 1977- First fiber link with live telephone traffic-GTE Long Beach 6 Mb/s• May 1977- First Bell system 45Mb/s links: GaAs lasers 850nm Multimode -2dB/km loss• Early 1980s- InGaAsP 1.3 µm Lasers: 0.5 dB/km, lower dispersion-Single mode Sharif University of Technology

11. Chapter 1 Introduction Optical Fiber Communications History of Optical Telecommunications (3 of 3) • Late 1980s-Single mode transmission at 1.55 µm - 0.2 dB/km• 1987- 1.3 um InGaAsP lasers, SMF, 1.7 Gb/s at 50km• 1989- Erbium doped fiber amplifier• 1990s- 1.55 um InGaAsP DFB lasers, SMF, 2.5-10 Gb/s at 40km• 1990s- WDM, 1.55 um InGaAsP DFB lasers, EDFA, SMF, 2.5-10Gb/s at 300-10,000km repeater spacing• 1 Q 1996- 8 Channel WDM• 4th Q 1996- 16 Channel WDM• 1Q 1998- 40 Channel WDM• 2002- 64 WDM chx 10Gbps over 250,000 km span Sharif University of Technology

12. Chapter 1 Introduction Optical Fiber Communications Increase in Bitrate-Distance product Sharif University of Technology

13. Chapter 1 Introduction Optical Fiber Communications Per-Fiber Capacity Trends Sharif University of Technology

14. Chapter 1 Introduction Optical Fiber Communications Optical Fiber vs. Twisted-Pair Cable & Coaxial Cable Sharif University of Technology

15. Chapter 1 Introduction Optical Fiber Communications Benchmark between Optical Fibers and Twisted-Pair Cable Sharif University of Technology

16. Chapter 1 Introduction Optical Fiber Communications Optical Signal Processing (1 of 2) • With the development of network communication, the transmitted signals need further processed such as switching, add-drop multiplexing, - Processing in electronic domain Sharif University of Technology

17. Chapter 1 Introduction Optical Fiber Communications Optical Signal Processing (2 of 2) - Processing in optical domain (discrete component) Sharif University of Technology

18. Chapter 1 Introduction Optical Fiber Communications Progress in Lightwave Communication Technology (1 of 5) • First Generation Fiber Optic Systems - Purpose: Eliminate repeaters in T-1 systems used in inter-office trunk lines - Technology: 0.8 μm GaAs semiconductor lasers, Multimode silica fibers - Limitations: Fiber attenuation, Intermodal dispersion - Deployed since 1974• Second Generation Fiber Optic Systems - Opportunity: Development of low-attenuation fiber (removal of H2O and other impurities), Eliminate repeaters in long-distance lines Sharif University of Technology

19. Chapter 1 Introduction Optical Fiber Communications Progress in Lightwave Communication Technology (2 of 5) - Technology: 1.3 μm multi-mode semiconductor lasers, Single- mode, low-attenuation silica fibers, DS-3 signal: 28 multiplexed DS-1 signals carried at 44.736Mbits/s - Limitation: Fiber attenuation (repeater spacing ≈ 6km) - Deployed since 1978• Third Generation Fiber Optic Systems - Opportunity: Development of erbium-doped fiber amplifiers - Technology: 1.55 μm single-mode semiconductor lasers, Single- mode, low-attenuation silica fibers, OC-48 signal: 810 multiplexed 64-kb/s voice channels carried at 2.488 Gbits/s Sharif University of Technology

20. Chapter 1 Introduction Optical Fiber Communications Progress in Lightwave Communication Technology (3 of 5) - Limitations: Fiber attenuation (repeater spacing ≈ 40 km), Fiber dispersion - Deployed since 1982 Sharif University of Technology

21. Chapter 1 Introduction Optical Fiber Communications Progress in Lightwave Communication Technology (4 of 5)• Fourth Generation Fiber Optic Systems - Opportunity: Deregulation of long-distance market - Technology: 1.55 μm single-mode, narrow-band semiconductor lasers, Single-mode, low-attenuation, dipersion-shifted silica fibers, Wavelength-division multiplexing of 2.488Gb/s or 9.953Gb/s signals - Limitations: Nonlinear effects limit the following system parameters (Signal launch power, Propagation distance without regeneration/reclocking, WDM channel separation, Maximum number of WDM channels per fiber), Polarization-mode dispersion limits the following parameters (Propagation distance without regeneration/reclocking) - Deployment began in 1994 Sharif University of Technology

22. Chapter 1 Introduction Optical Fiber Communications Progress in Lightwave Communication Technology (5 of 5) Sharif University of Technology

23. Chapter 1 Introduction Optical Fiber Communications Generic Optical Fiber System (1 of 3) Sharif University of Technology

24. Chapter 1 Introduction Optical Fiber Communications Generic Optical Fiber System (2 of 3) Sharif University of Technology

25. Chapter 1 Introduction Optical Fiber Communications Generic Optical Fiber System (3 of 3) Sharif University of Technology

26. Chapter 1 Introduction Optical Fiber Communications Important Communication Systems and Technologies (1 of 3)• Wide-area networks - Either government-regulated or in the public network environment ◦ WANS originated in telephony - Main technologies: SONET/SDH, ATM, WDM ◦ Voice circuits vs. packets ◦ Non-optical technologies (unless encapsulated in SONET or ATM): T1/E1/J1, DS-3, Frame Relay ◦ Standards bodies include ITU-T, IETF, ATM Forum, Frame Relay Forum, IEEE Sharif University of Technology

27. Chapter 1 Introduction Optical Fiber Communications Important Communication Systems and Technologies (2 of 3)• Metropolitan-area/regional-area networks - A MAN or RAN covers a North American metropolitan area, or a small to medium-sized country in Europe or Asia - Main technologies: SONET, ATM, Gigabit & 10-Gigabit Ethernet, DWDM◦ Non-optical technologies: T1, T3, Frame Relay• Local-area networks - Main technologies: Ethernet, Fast Ethernet, Gigabit Ethernet - Currently fiber for backbone, copper for distribution - Excess capacity enhances performance Sharif University of Technology

28. Chapter 1 Introduction Optical Fiber Communications Important Communication Systems and Technologies (3 of 3)• Access networks - The first (or last) network segment between customer premises and a WAN or MAN ◦ Owned by a Local Exchange Carrier (LEC) - Broadband digital technologies: HFC, DSL ◦ Ethernet framing vs. ATM - Twisted pair vs. coaxial cable vs. fiber vs. wireless vs. free- space optics Sharif University of Technology

29. Chapter 1 Introduction Optical Fiber Communications Optical “Food Chain” Sharif University of Technology

30. Chapter 1 Introduction Optical Fiber Communications Optical Communication Protocol Stack Sharif University of Technology

31. Chapter 1 Introduction Optical Fiber Communications Optical Network Architecture (1 of 2) WDM provides enabling technology for Optical Network Layer: Data format transparency for multi-service optical layer Optical channel bandwidth management and high-capacity throughput Sharif University of Technology

32. Long Haul Metro Access Chapter 1 Introduction Optical Fiber Communications Optical Network Architecture (2 of 2) Sharif University of Technology

33. Chapter 1 Introduction Optical Fiber Communications Traffic Growth and Composition Sharif University of Technology

34. Chapter 1 Introduction Optical Fiber Communications DWDM Technology (1 of 2) ∆λ = 25 – 100GHz (0.4 or 0.8 nm @ 1500 nm) Sharif University of Technology

35. Chapter 1 Introduction Optical Fiber Communications DWDM Technology (2 of 2) Sharif University of Technology

36. Chapter 1 Introduction Optical Fiber Communications Evolution of WDM System Capacity• Repeater spacing for commercial systems - Long-haul systems - 600 km repeater spacing - Ultra-long haul systems - 2000 km repeater spacing (Raman + EDFA amplifiers, forward error correction coding, fast external modulators) - Metro systems - 100 km repeater spacing• State of the art in DWDM - channel spacing 50 GHz, 200 carriers, 10 Gb/s, repeater spacing few thousand km Sharif University of Technology

37. Chapter 1 Introduction Optical Fiber Communications Global Undersea Fiber systems Sharif University of Technology

38. Chapter 1 Introduction Optical Fiber Communications Installed Fiber in US Sharif University of Technology

39. Chapter 1 Introduction Optical Fiber Communications Professional Societies and Corporations (1 of 2)• Optical Society of America (OSA) - Oldest optics/photonics society in North America - Covers all fields of optics, from human vision to optical physics Peer-reviewed journals include Journal of the Optical Society of America, Applied Optics, Optics Letters, Journal of Light wave Technology (co-sponsored with IEEE-LEOS), Journal of Optical Networking, Optics Express• IEEE Lasers and Electro-Optics Society (IEEE-LEOS) - Journal of Quantum Electronics, Photonics Technology Letters, Journal of Special Topics in Quantum Electronics Sharif University of Technology

40. Chapter 1 Introduction Optical Fiber Communications Professional Societies and Corporations (2 of 2) - Co-sponsors the Optical Fiber Communication Conference (OFC) and the Conference on Lasers and Electro-Optics (CLEO) with OSA• SPIE - Not-for-profit corporation - Organizes many conferences and publishes proceedings Sharif University of Technology

41. Chapter 1 Introduction Optical Fiber Communications • LUCENT (www.lucent.com): adding more lanes Three Giant Companies (1 of 3) Sharif University of Technology

42. Chapter 1 Introduction Optical Fiber Communications • NORTEL (www.nortelnetworks.com): providing faster transport equipments Three Giant Companies (2 of 3) Sharif University of Technology

43. Chapter 1 Introduction Optical Fiber Communications • CISCO (www.cisco.com): raising the speed limit Three Giant Companies (3 of 3) Sharif University of Technology

44. Chapter 1 Introduction Optical Fiber Communications Questions ? Sharif University of Technology