Outline

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 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
6
Next generation optical networks 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 challengesfor the 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

• Types and 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

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 (lt 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
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

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
• ATT offers 1000 or more mirrors
• Lucent offers 1024 ports in their LambdaRouter

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 41 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
TX
RX
21
WDM System
22
Testing WDM Systems

• Eye 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 Eye Diagram
24
WDM Experimental Systems

• 320 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 components

• Power 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 and Transparent 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, "The Lucent
  LambdaRouter MEMS technology of the future here
  today," 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, "A Novel
  rearrangeable Non-Blocking Architecture for MEMS
  Optical Space Switch," 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.
  10451047, July 1998.
• K. Fukuchi et al., "10.92 Tb/s (273 x 40 Gb/s)
  Triple-band/ultra-dense WDM Optical-Repeatered
  Transmission Experiment," OFC 2001 Technical
  Digest, 2001, pp. PD24/13.
• 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 Pages1615 - 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 1178 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.

27
WDM Technology References

• Rajiv Ramaswami Optical Fiber Communication
  From Transmission to Networking
  http//www.comsoc.org/livepubs/ci1/public/anniv/ra
  ma.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.htm
  l
• http//www2.rad.com/networks/1999/wdm/wdm.htmFigu
  re15

28
Questions

• When an optical 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 next

• Answer 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?