Optical tech

Optical tech

• 1.
  Outline Basic components Optical network evolution Next generation AON WDM systems Components Architecture Commercially existing systems Developing systems Optical Cross-connects Components Architecture Commercially existing systems Developing systems Other related optical components References Questions
• 2.
  Optical Technology –Recent Advances Jan-31-2004 Farid Farahmand
• 3.
  Optical components FDL Delay devices Optical buffers DWDM Technical challenges Synchronizations Current system developments Spacing and TDM maximum rates it can handle Coarse WDM Wavelength converters Availability Optical switching technology Bubbles Mirrors Fiber technology ADM and multiplexers Amplifiers Synchronization issues Switching related issues Optical phase locked loops Optical transmitters and receivers Cost of optical devices Cost of fiber installation Optical devices Electronic devices Optical system infrastructure How many miles of fiber SONET applications Typical system capacity Available networks Optical attenuators Operating range Receivers and transmitters Wavelength range Operating band (L,S, etc.) Sensitivity and output power Bit error rate What is expected traffic growth? What are they saying? Useful references and web pages
• 4.
  Emerging network [7,19,20]
• 5.
  Next generation networks [19,20,7] 2010+ 2005-2010 1999-2005 Now Fourth Third Second First Generation/ Availability Transparent Transparent Opaque Opaque Transparent Opaque Opaque Opaque Types: Network/ Switch Pb/s 100 Tb/s 100 Gb/s – Tb/s - Capacity Packet-based Dynamic Dynamic - Static Path Control Mesh Mesh/Ring WDM Ring P2P WDM Topology OXC with WLC OXC (Layers approach – no WLC) OADM (with switch) OADM (point-to-point with no switch)
• 6.
  Next generation opticalnetworks Characteristics The core architecture must be independent of signal format and bit rate The edge must be flexible to handle variety of signal types Provides various services (easily provisionable) Have reasonable cost, high scalability Network and node Supports performance monitoring
• 7.
  Technological challenges forthe NGN Innovation in devices Small and low-cost optical interfaces VLSI, Fast programmable devices Fast clock and data recovery devices (CDR) High pin-count, low power Hybrid designs (photonic and electronic integration) Transmission technology High efficiency (high spectral efficiency) Use all bands Cost per bit Long haul transmission Node technology WL conversion capacity Small footprint Less heat and power Network software More intelligent networks Considering the physical layer limitations Developing autonomous systems WDM technology and Switching technology
• 8.
  Optical Cross-connects Typesand Capabilities Basic components Architecture [2,4,6] Commercially available systems Reported experimental systems
• 9.
  Optical Switching Technology A critical component in all-optical networks Eliminates O-e-O converters Reducing the cost Key component in many optical devices: Wavelength monitoring devices Protection switching and restoration OADM and OXC Power limiters and variable attenuators Basic issues Categories (device types) Architectures [2,4,6] Technological limitations Mechanisms Bit rate Cost of O-e-O
• 10.
  Optical Switching TechnologyCategories Opto-mechanical optical switches Wave guide solid state optical switches Electro-optical [18] Thermal-optical Acousto-optical Liquid-crystal [3] Micro-electromechanical optical switches MEMS (2D and 3D) [5, 9,10,11,12,16] Bubble optical switches [5,16]
• 11.
  Optical Switching TechnologyCategories – Characteristics [18] Opto-mechanical optical switches Good performance; slow switching time; low cost; large size (IEEE march 2002 page 89) Very low insertion (< 1dB); 1x2 or 2x2 switches; low port count Wave guide solid state optical switches Thermally changing the refractive index of the waveguide Fast switching time; high cost; poor insertion loss liquid crystal (changing polarization of incident light)–good insertion loss Lithium niobate technology (changing the refractive index changes) Micro-electromechanical optical switches High performance; low loss; small size; reasonable price; moderate switching time Bubble optical switches High performance; low loss; small size; reasonable price; slow switching time
• 12.
  Optical Switching TechnologyCategories
• 13.
  Switching [16,1] OXC Capacities Types Optical Fabric Optical Fabric With standard interface (1.3 or 1.5 um) Optical transport System (L,C, S, etc.) Electrical Fabric
• 14.
  Optical Switching TechnologyMEMS technology – An introduction [9,10,11,12] Micro-electromechanical switches Fabricated on silicon substrate Mature technology – similar to silicon integrated circuits Starting with silicon wafer At the end of the process a part of it is etched away – leaving pieces free to move Small in size (few hundred microns) Proven to be robust, long lived, and reliable The basic idea is that the incoming light is reflected to outlet port Micro mirrors (free space) Independent of the data rate Operating over the entire 1.3-1.6 u optical communication band Very low optical losses (about 1.25 dB) MEMS mirror arrays can have 256-1024 mirrors (Lucent) MEMS technology 2D (digital – standup and lie down positions – 45 degree position) 3D (analog – two-axis motion) Compared to other technologies Provides a small footprint Reliable Full movement range Bit rate Cost MEMS-based Fabric Electronic Fabric
• 15.
  Optical Switching TechnologyMEMS technology – Basic Operation Performance parameters: [9,10,11] Path length dependent Loss due to angular mirror Loss due to clipping of light at the mirror boundaries Applications Protection and monitoring Optical add/drop operations Main issue: Port count (NxN mirrors) High loss for large port counts (path length grows linearly with N) Availability AT&T offers 1000 or more mirrors Lucent offers 1024 ports in their LambdaRouter MEM 2D
• 16.
  Optical Switching TechnologyMEMS technology – 3D MEMS 3D MEMS More complex The mirror tilts freely path length grows with squre(N) thus resulting in less loss Research areas Packaging and physical layer issues [9,10,11] Algorithms to reduce the number of mirrors as port count increases [12] Multi-stage switches [17]
• 17.
  Available High-capacity Systems The Aurora Optical Switch offers carriers of telecommunications services the flexibility of supporting up to 512 OC-48c/STM-16 ports or 128 OC-192c/STM-64 ports to a total of 1.28 Tbpsbi directional traffic. NEC's ultra-dense DWDM system (SpectralWave) It supports up to 160 2.5G and 10G wavelengths on a single fiber. The system's advanced feature set includes 4:1 multiplexing to carry four OC-48/STS-16 signals to be carried on a single 10G wavelength, Astral Point (Alcatel) - OA 500 Modular Optical System With a switch fabric that scales from 320Gb/s to 1.28 terabits, and interfaces that scale from DS1 to OC768, the ON 7000 SONET node meets carrier metro and regional inter-office transport needs for years to come. The node incorporates the highest port densities per bay of any announced product in the metro optical network equipment market. It can transport 576 DS3's, 864 OC3's, 288 OC12's, 72 OC48's and 36 OC192's per 45u bay. Lucent ( LambdaXtreme ) It carries up to 2.56 Terabits per second at 40G wavelengths as far as 1,000km (625mi) — and 1.28Tbps at 10G wavelengths for 4,000km (2,500mi) Lucent ( WaveStar OLS ) provides a 1.6 Tbps (up to 160 x 10Gbps wavelength) capacity over a single fiber
• 18.
  Available High-capacity Systems [5]
• 19.
  WDM System [13,14,15] A critical component to the high-speed high-capacity AON Critical factor: capacity x distance product and the number of spans required Capacity: TDM technology x WDM spacing Spacing: Physical limitations, number of bands utilized Distance: Physical limitations, SNR, Dispersion, Transmission lines, etc. Critical components: TX, RX, Transmission line, Amplifiers Discussion Types and Capabilities Basic components Architecture Commercially available systems Reported experimental systems
• 20.
  WDM System TXRX
• 21.
  WDM System
• 22.
  Testing WDM SystemsEye Diagram Bit error rate In presence of random noise: Inter Symbol Interference (ISI) penalty CDR Jitter tolerance Receiver sensitivity Minimum amount of power required to operate Bit error rate vs. input power (dBm) -21 dBm give about 10^-9 error rate
• 23.
  Example of EyeDiagram
• 24.
  WDM Experimental Systems320 Gbps System: 32 Channels; 10 Gbps / channel; 100 GHZ spacing; 500 Km; 125 Km per span – 1998 [13] Using dual-stage flat-gain EDFA amplifiers Single band [1-16 and 17-32] 1532-1562 nm range 10.92 Tbps System: 273 Channels; 40 Gbps / channel; 50 GHZ spacing; 250 Km; 2 spans – 2001 [14] Triple band: S,C, L; separating even and odd channels S Band: 1476.81 – 1508.01 nm (85 Channels) C Band: 1526.83 – 1563.05 nm (92 channels) L Band: 1570.01 – 1620.06 nm (96 channels) Using gain shifted thulium doped fiber amplifier 2.56 Tbps System: 64 Channels; 40 Gbps / channel; 100 GHZ spacing; 6000 Km; (used for submarine systems) – 2003 [15] Diving single BW to two parts: 1540 – 1565 nm and 1570 – 1595 nm each having 32 channels; separating even and odd channels (band dividing) Used a feedback mechanism to lower the transmission line non-liearity impact
• 25.
  Other optical componentsPower monitor www.protodel.com No tapping Non-invasive Tunable lasers www.agilent.com Ranges of 1260-1640 nm (E,S,C, L) Used for CWDM (coarse WDM)
• 26.
  References Opaque andTransparent Networking (Optical Networks Magazine, Tutorial Corner, May/June 2003) Role of Optical Network in ResilientIP Backbone Architecture (Optical Networks Magazine, Tutorial Corner, Sep./Oct. 2003) All-Optical Liquid-Crystal Signal Processing Technologies for WDM Networks Jung-Chih Chiao, Kuang-Yi Wu, Jian-Yu Liu, Chorum Technologies, USA 0 Optical Networks Magazine, May/June 2003 Architectures, Technology, and Strategies for Gracefully Evolving Optical Packet Switching Networks Alexandros Stavdas, National Technical University of Athens, Greece Optical Networks Magazine, May/June 2003 All-Optical Switching for High Bandwidth Optical Networks M. J. Potasek, New York University, USA Optical Networks Magazine Vol. 3, Issue 6 November/December 2002 Design and Performance of Optical Cross-Connect Architectures with Converter Sharing Teck Yoong Chai, Tee Hiang Cheng, and Gangxiang Shen, Nanyang Technological University, Sanjay K. Bose, Indian Institute of Technology, and Chao Lu, Nanyang Technological University Optical Networks Magazine Vol. 3, Issue 4 July/August 2002 N. Ghani, K. Sivalingam (Editors), Optical Networks , Special Issue on Topics in Optical Communications, to appear Spring 2004 Volume: 41,   Issue: 9,   Year: Sept. 2003 DWDM: Networks, Devices, and Technology Jajszczyk, A. Page(s): 29- 33 Communications Magazine, IEEE D. Bishop, C. Giles, and G. Austin, &quot; The Lucent LambdaRouter : MEMS technology of the future here today,&quot; Volume: 40,   Issue: 3,   Year: March. 2002 Communications Magazine, P. B Chu, S. Lee, and S. Park, ?MEMS: The Path to Large Optical Crossconnects” Volume: 40,   Issue: 3,   Year: March. 2002 Communications Magazine, P. Dobbelaere, K. Falta, L. Fan, S. Patra, “Digital MEMS for optical switching” Volume: 40,   Issue: 3,   Year: March. 2002 Communications Magazine, Gangxiang Shen , Sanjay K. Bose, Tee Hiang Cheng, Chao Lu, and Teck Yoong Chai, &quot; A Novel rearrangeable Non-Blocking Architecture for MEMS Optical Space Switch ,&quot; Optical Network Magazine, vol. 3, no. 6, November/December 2002, pp. 70-79. S. Bigo, A. Bertaina, M. W. Chbat, S. Gurib, J. Da Loura, J.-C. Jacquinot, J. Hervo, P. Bousselet, S. Borne, D. Bayart, L. Gasca, and J.-L. Beylat, “320-Gb/s (32 10 Gb/s WDM) transmission over 500 km of conven-tional single-mode fiber with 125-km amplifier spacing,” IEEE Photon. Technol. Lett ., vol. 10, pp. 1045–1047, July 1998. K. Fukuchi et al. , &quot;10.92 Tb/s (273 x 40 Gb/s) Triple-band/ultra-dense WDM Optical-Repeatered Transmission Experiment,&quot; OFC 2001 Technical Digest , 2001, pp. PD24/1–3. 2.56-Tb/s (64/spl times/42.7 Gb/s) WDM transmission over 6000 km using all-Raman amplified inverse double-hybrid spans Morisaki, M.; Sugahara, H.; Ito, T.; Ono, T.; Photonics Technology Letters, IEEE  ,Volume: 15 , Issue: 11 , Nov. 2003 Pages:1615 - 1617 Jajszczyk A., Automatically Switched Optical Networks (ASON) , 2003 Workshop on High Performance Switching and Routing HPSR 2003, Torino, Italy, June 24-27, 2003 Page 1 178 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 20, NO. 2, FEBRUARY 2002 Architectural Design for Multistage 2-D MEMS Optical Switches Gangxiang Shen, Member, IEEE, Tee Hiang Cheng, Member, IEEE, Sanjay K. Bose R. Ramaswami and KN sivarajan, “ Optical Networks : A PracticalProspective ”, San Francisco, CA, Morgan Kaufmann Publishers, Inc. 1998 Shigeki Aisawa, Atsushi Watanabe, Takashi Goh, Yoshihiro Takigawa, Moasafumi Koga and Hiroshi Takahashi, Advances in Optical Path Crossconnect Systems Using Planar-Lightwave Circuit-Switching Technologies, IEEE Communications Magazine , vol. 41, no. 9, September 2003, pp. Botaro Hirosaki , Katsumi Emura , Shin-Ichiro Hayano , Hiroyuki Tsutsumi , &quot;Next-generation optical networks as a value creation platfom &quot; , IEEE Communications Magazine, no. 9, Sep 2003 pp. 65-71
• 27.
  WDM Technology ReferencesRajiv Ramaswami Optical Fiber Communication: From Transmission to Networking http://www.comsoc.org/livepubs/ci1/public/anniv/rama.html http:// www.telcite.fr/nwdmen.htm http://www.ngk.co.jp/english/new_rele/2000/2000_07_18_02.htm http://www.spie.org/web/oer/november/nov00/wdm.html http://www2.rad.com/networks/1999/wdm/wdm.htm#Figure15
• 28.
  Questions When anoptical signal is dropped on a node (receiver) how much power do we need? That is the minimum receiver sensitivity? This is useful for determining how practical tap-and-continue devices are Impact of synchronization in WDM system, should WL be synchronized? To what degree? WLC, how practical are they where are the recent developments?
• 29.
  What is nextAnswer the questions Present a better view of the network and its needs More on proposed switch architecture [2,4,6] and the difference with the planar lightwave circuit switching [19,20] We talk about optical amplitiers What is the difference between the optical and electrical amplifiers requiring 3R? Both costwise and size wise Is the size an issue? What about the delay? So optical amplifiers are very critical in all-optical network design? In case of OeO is the amplifier format/rate dependent? I am sure it is because it does some kind of B1 error checking, as is the case for SONET About wavelength conversions and their technological advances The main issue is that current WLC are big and bulky, design wise they are very bulky. So it have 1024 of them …you can imagine the problem So what can be done? Make them smaller? Can you find a module from Alcatel? More on optical devices: filtering devices, tap-and-continue devices What is Autonomous Switched Optical Networks (ASON) and why are they useful [16] Some basic information on the difference between the SOA and EDFA amplifiers – their BW, output power, gain, etc. So what are the regeneration techniques? What is the problem if you convert the incoming WL into electrical signals?