DWDM Tutorial Prerequisite Training - Fujitsu

1 DWDMT utorialNovember 15, 2002 Prerequisite TrainingPrerequisite TrainingDWDMR elease , November 15, 2002 All other products or services mentioned in this document are identified by the trademarks, service marks,or product names as designated by the companies that market those products or services or own thosemarks. Inquiries concerning such products, services, or marks should be made directly to those companiesThis document and its contents are provided by Fujitsu Network Communications, Inc. (FNC) for guidancepurposes only. This document is provided as is with no warranties or representations whatsoever, eitherexpress or implied, including without limitation the implied warranties of merchantability and fitness for pur-pose. FNC does not warrant or represent that the contents of this document are error free. Furthermore, the contents of this document are subject to update and change at any time without notice byFNC, since FNC reserves the right, without notice, to make changes in equipment design or componentsas progress in engineering methods may warrant.

2 No part of the contents of this document may be copied,modified, or otherwise reproduced without the express written consent of and Copyrights Unpublished work and only distributed under restriction. Copyright Fujitsu Network Communications, Inc. All Rights Reserved. FNC is a trademark of Fujitsu Network Communications, Inc. (FNC).Alcatel is a registered trademark of TeraLight is a trademark of is a registered trademark of Corning CorporationDS and SMF-28 are trademarks of Corning CorporationDS is a trademark of CorningE-LEAF is a registered trademark of is a trademark of Lucent Plus, TrueWave RS and TrueWave Classic are registered trademarks of Lucent CorporationSEI PureGuide is a trademark of Sumitomo Electric Industries (SEI)IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Incorporated. Release , November 15, 2002iDWDMT able of ContentsPurpose.

3 1 Objectives .. 1 Why dwdm ? .. 2 Discrete Transport Channels vs dwdm Transport .. 2 Service Provider Advantages .. 3 Types of multiplexing .. 4 Time division multiplexing .. 4 wavelength division multiplexing .. 5 Varieties of WDM .. 5 WDM .. 5 CWDM .. 5 dwdm .. 5 Optical multiplexing Technology .. 6 Optical multiplexing Filters .. 6 Thin-Film Filter .. 6 Fiber Bragg Gratings .. 7 Arrayed Waveguides .. 8 Periodic Filters, Frequency Slicers, Interleavers .. 9 Optical Network .. 10 Tunable Laser .. 11 Lasers as the Signal Source .. 11 Safety Concerns .. 11 Modulator .. 12 Amplifiers and Regeneration .. 12 Network Routes and Regeneration .. 13 Erbium-Doped Fiber Amplifiers .. 13 The EDFA Amplifier .. 14 Fiber Bands .. 14 Amplifier Requirements .. 14 Raman Amplifiers .. 15 Distributed Raman .. 15 Other Optical Amplifiers .. 16 Optical Network Considerations.

4 17 Signal Bandwidth and Filtering .. 17 ITU-T Grid .. 18 Signal Power in the System .. 18 Coding Types .. 19 Non-Return to Zero .. 19 Return to Zero .. 19 Optical Duobinary .. 20 Carrier Suppressed Return-to-Zero .. 20 Impairments to dwdm Transmission .. 21 Bit Error Rate .. 21 Eye Pattern .. 21 Forward Error Correction - Solution to BER .. 22Q-Factor .. 23 DWDMT able of ContentsRelease , November 15, 2002iiOptical Signal-to-Noise Ratio .. 23 Types of Forward Error Correction .. 24In-Band FEC .. 24 Out-of-Band FEC .. 24 Receiver Parameters .. 25 Noise Figure .. 25 Nonlinear OSNR Impairments .. 26 Spectrum after Preemphasis .. 26 The Optical Media .. 27 Optical Fiber Characteristics .. 27 Fibers .. 27 SMF Fiber Designs .. 28 Fiber Attenuation .. 29 Attenuation Loss in S-, C-, and L-Bands .. 29 Attenuation of Optical Signal .. 30 Signal Amplification.

5 30 Cross-Talk in dwdm Systems .. 31 Compensating for Cross-Talk in dwdm Systems .. 31 Fiber Dispersion .. 31 Chromatic Dispersion .. 31 Chromatic Dispersion Tolerance .. 32 Dispersion Compensators .. 33 Dispersion Slope and Limits .. 33 Chirp .. 34 Polarization Mode Dispersion .. 35 PMD Effect .. 35 Polarization Mode Dispersion Compensation .. 37 Effective Polarization Mode Dispersion Compensation .. 37 End of Course Evaluation .. 38 dwdm Self-Evaluation .. 38 Self-Evaluation Sheet (Electronic) .. 41 Release , November 15, 2002iiiDWDMList of FiguresFigure 1: Discrete Channels .. 2 Figure 2: dwdm Transport .. 2 Figure 3: Time division multiplexing .. 4 Figure 4: wavelength division multiplexing .. 5 Figure 5: WDM Filters .. 6 Figure 6: Thin-Film Filter Concept .. 7 Figure 7: Fiber Bragg Grating .. 7 Figure 8: Arrayed Waveguide (Demultiplexer).

6 8 Figure 9: Combined Devices .. 9 Figure 10: Optical Network Drawing .. 10 Figure 11: Tunable Laser .. 11 Figure 12: Laser Signal Sources .. 12 Figure 13: Regeneration .. 12 Figure 14: Network Regeneration .. 13 Figure 15: EDFA .. 13 Figure 16: EDFA Amplifier .. 14 Figure 17: Fiber Bands and Amplifiers .. 14 Figure 18: Distributed Raman Amplifiers .. 15 Figure 19: Optical Amplifiers .. 16 Figure 20: Optical Network Spectrum .. 17 Figure 21: Signal Bandwidth .. 17 Figure 22: dB ratio .. 18 Figure 23: Reference Power .. 18 Figure 24: Non-Return to Zero .. 19 Figure 25: Return to Zero .. 19 Figure 26: Optical Duobinary .. 20 Figure 27: Eye Pattern vs. Data Stream .. 21 Figure 28: Eye Pattern Display .. 22 Figure 29: Forward Error Correction .. 22 Figure 30: Q-Factor .. 23 Figure 31: OSNR .. 23 Figure 32: OOB-FEC Example.

7 24 Figure 33: Receiver Parameters .. 25 Figure 34: Noise Figure .. 25 Figure 35: Before Preemphasis .. 26 Figure 36: After Preemphasis .. 26 Figure 37: Optical Media .. 27 Figure 38: MMF and SMF .. 27 Figure 39: Fiber Mechanical Construction .. 28 Figure 40: Fiber Attenuation .. 29 Figure 41: Fiber Signal Loss in S-, C-, and L-Bands .. 29 Figure 42: Power Levels .. 30 Figure 43: Dispersion and WDM .. 31 Figure 44: Chromatic Dispersion .. 32 Figure 45: Dispersion Effects .. 32 Figure 46: Compensation Modules .. 33 DWDMList of FiguresRelease , November 15, 2002ivFigure 47: Dispersion Slope and Limits .. 34 Figure 48: Chirp .. 35 Figure 49: Polarization Mode Dispersion .. 36 Figure 50: PMD Compensation .. 37 Release , November 15, 20021 TutorialDWDMP urposeThis Tutorial provides Prerequisite information about dense wavelength division multiplexing ( dwdm ) systems.

8 Since dwdm systems are derived from wavelength division multiplexing (WDM) systems, and recently the introduction of coarse wavelength division multiplexing (CWDM) systems each of these similar technologies will be discussed and inter related to dwdm . This material is applicable to all dwdm courses offered by Fujitsu Network Communications, Inc. (FNC). A list of acronyms used in this Tutorial is in Table 2, and Table 3 provides dwdm completion of this lesson, the student should be able to: Understand basic dwdm theory and operational concepts Describe functions of the major components used in dwdm Describe dwdm limitationsTutorialDWDMR elease , November 15, 20022 Why dwdm ?Dense wavelength division multiplexing permits rapid network deployment and significant network cost reduction. Use of dwdm allows deployment of less fiber and hardware with more bandwidth being available relative to standard SONET Transport Channels vs dwdm TransportTraditional SONET, TCP/IP, ATM, and voice over Internet Protocol (VoIP)1 are transmitted over discrete channels, each requiring a fiber pair between the end points.

9 Figure 1 shows nine channels, each at 10 Gb/s, using nine discrete fiber pairs. This traditional SONET method requires 3 regenerators to condition the signals across each fiber path between each of the nine nodes, a total of 27 1: Discrete ChannelsDense wavelength division multiplexing systems allow many discrete transport channels to be carried over a single fiber pair. Nine discrete channels share the fiber pair with an aggregate bandwidth of 90 Gb/s in Figure 2: dwdm Transport1 VoIP is a method of digitizing voice to allow it to occupy less bandwidth and therefore allow more voice channels over a given XSONET9 XSONETSONET NE REGEN REGEN REGEN SONET NE ILAILAILADWDMDWDM9 XSONET SONET NE ILA ILA ILA SONET NE 9 XSONETR elease , November 15, 20023 TutorialDWDMS ervice Provider AdvantagesThe service provider uses an existing installed fiber plant more effectively by incorporating dwdm systems.

10 Comparing Figure 1 to Figure 2, the service provider recovers eight fiber pairs to expand its network for its investment in two 9-channel ( wavelength ) dwdm terminals and three in-line amplifiers (ILAs), as described reduces the cost per bit sent and received over the network. In Figure 1, the distances require three regenerator sites for traditional SONET traffic. In Figure 2, these 27 regenerators are removed and replaced by three ILAs. The cost of an ILA is typically 50 percent of the cost of a SONET regenerator and the single ILA carries all nine traffic of all types can now be carried over the dwdm infrastructure shown in Figure 2. Thereby enabling faster speed to market of multiservice traffic offerings at a lower cost for new services to be transported over the dwdm , November 15, 20024 Types of MultiplexingMultiplexing is sending multiple signals or streams of information through a circuit at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end.