101483423-Fiber-Characterization-Training.pdf

1. Fiber Characterization Assessing the fiber’s capacity` Assessing the fiber’s capacity` Tim Yount Market Manager - Fiber Optic Test Solutions JDSU Fiber Optic Division

2. Optical Communication Networks There are a large variety of network topologies possible according to distance reach, environments, bandwidth and transmission speeds. High Speed DWDM network Access/FTTx network - HFC, RFoG, Docsis PON © 2007 JDSU. All rights reserved. 2 Buildings Multi-home Units Residential CO/Headend/M TSO Local Convergence Point Network Access Points

3. Fiber Review Singlemode Optical Fiber

4. Light propagation is a function of Attenuation, dispersion and non-linearities. 0 1 2 2 = = = = + + + + ∂ ∂ ∂ ∂ − − − − + + + + ∂ ∂ ∂ ∂ A A A A i A i γ γ γ γ β β β β α α α α NOT FOR USE OUTSIDE VERIZON AND JDSU 4 Attenuation, Dispersion, 0 2 1 2 2 2 = = = = + + + + − − − − + + + + ∂ ∂ ∂ ∂ A A dT A A i z A i γ γ γ γ β β β β α α α α

8. Elements of Loss Fiber Attenuation Caused by scattering absorption of light as it travels through the fiber Measured as function of wavelength (dB/km) © 2007 JDSU. All rights reserved. 8 Pin (Emitted Power) Pout (Received power) Power variation OTDR Trace of a fiber link

9. Bending Losses Microbending – Microbending losses are due to microscopic fiber deformations in the core-cladding interface caused by induced pressure on the glass © 2007 JDSU. All rights reserved. 9 the glass Macrobending – Macrobending losses are due to physical bends in the fiber that are large in relation to fiber diameter Attenuation due to macrobending increases with wavelength (e.g. greater at 1550nm than at 1310nm)

10. Optical Return Loss (ORL) Amount of transmitted light reflected back to the source PAPC PPC Pelement PAPC PBS PBS PBS Source (Tx) Receiver (Rx) PR © 2007 JDSU. All rights reserved. 10 PT: Output power of the light source PAPC: Back-reflected power of APC connector PPC: Back-reflected power of PC connector PBS: Backscattered power of fiber PR: Total amount of back-reflected power ORL (dB) = 10.Log 0 ) ( R T P P PT ORL is measured in dB and is a positive value. The higher the number, the smaller the reflection - yielding the desired result.

11. Effects of High ORL (Low values) Increase in transmitter noise – Reducing the OSNR in analog video transmission – Increasing the BER in digital transmission systems Increase in light source interference – Changes central wavelength and output power © 2007 JDSU. All rights reserved. 11 – Changes central wavelength and output power Higher incidence of transmitter damage The angle reduces the back-reflection of the connection. SC - PC SC - APC

12. Chromatic Dispersion Chromatic Dispersion (CD) is the effect that different wavelengths (colors or spectral components of light) travel at different speed in a media (Fiber for ex.) The more variation in the velocity, the more the individual pulses spread which leads to overlapping. © 2007 JDSU. All rights reserved. 12 Pulse Spreading

13. Dispersion Compensation The Good News: CD is stable, predictable, and controllable – Dispersion zero point and slope obtained from manufacturer – Dispersion compensating fiber (“DC fiber”) has large negative dispersion – DC fiber modules correct for chromatic dispersion in the link © 2007 JDSU. All rights reserved. 13 – DC fiber modules correct for chromatic dispersion in the link Tx Rx DC modules fiber span delay [ps] 0 d

14. V V Polarization Mode Dispersion Different polarization modes travel at different velocities presenting a different propagation time between the two modes (PSPs). The resulting difference in propagation time between polarization modes is called Differential Group Delay (DGD). PMD is the average value of the Differential Group Delay (mean DGD), so called PMD delay ∆τ ∆τ ∆τ ∆τ [ps], expressed by the PMD delay coefficient ∆τ ∆τ ∆τ ∆τc [ps/√km] © 2007 JDSU. All rights reserved. 14 DGD v1 v2 V1 V2 Perfect SM Fiber span

15. What are my PMD limitations ? According to the theoretical limits or equipment manufacturers specs, determine the PMD delay [ps] margin. – PMD varies randomly so abs. value to be used with care. – Consider margin knowing “typical” variation (from the data) occur in a 10-20% magnitude. What are my distance limitations due to PMD? – PMD coefficient [ps/√km ] calculated Max Distance @ 0.5ps√km © 2007 JDSU. All rights reserved. 15 10 Gbit/s (OC-192) 40 Gbit/s (OC-768 2.5 Gbit/s (OC-48) 6,400 km 400 km 25 km DGD v1 v2

16. Connector Contamination Understanding Contamination on Fiber Optic Connectors and Its Effect on Signal Performance

17. Focused On the Connection Bulkhead Adapter Fiber Connector Fiber Ferrule © 2009 JDSU. All rights reserved. JDSU CONFIDENTIAL PROPRIETARY INFORMATION 17 Fiber connectors are widely known as the WEAKEST AND MOST PROBLEMATIC points in the fiber network. Alignment Sleeve Alignment Sleeve Physical Contact

18. What Makes a GOOD Fiber Connection? Perfect Core Alignment Physical Contact The 3 basic principles that are critical to achieving an efficient fiber optic connection are “The 3 P’s”: Light Transmitted © 2009 JDSU. All rights reserved. JDSU CONFIDENTIAL PROPRIETARY INFORMATION 18 Physical Contact Pristine Connector Interface Core Cladding CLEAN Today’s connector design and production techniques have eliminated most of the challenges to achieving Core Alignment and Physical Contact.

19. What Makes a BAD Fiber Connection? A single particle mated into Today’s connector design and production techniques have eliminated most of the challenges to achieving CORE ALIGNMENT and PHYSICAL CONTACT. What remains challenging is maintaining a PRISTINE END FACE. As a result, CONTAMINATION is the #1 source of troubleshooting in optical networks. © 2007 JDSU. All rights reserved. 19 A single particle mated into the core of a fiber can cause significant back reflection, insertion loss and even equipment damage. DIRT Core Cladding Back Reflection Insertion Loss Light

20. Illustration of Particle Migration 11.8µ 15.1µ 10.3µ Core Cladding © 2007 JDSU. All rights reserved. 20 Each time the connectors are mated, particles around the core are displaced, causing them to migrate and spread across the fiber surface. Particles larger than 5µ usually explode and multiply upon mating. Large particles can create barriers (“air gaps”) that prevent physical contact. Particles less than 5µ tend to embed into the fiber surface, creating pits and chips. Actual fiber end face images of particle migration

21. Characterizing the Fiber Plant Understanding Fiber Link and Network Characterization

22. What is Fiber Characterization? Fiber Characterization is simply the process of testing optical fibers to ensure that they are suitable for the type of transmission (ie, WDM, SONET, Ethernet) for which they will be used. The type of transmission will dictate the measurement standards used © 2007 JDSU. All rights reserved. 22 Trans type Speed PMD Max CD Max SONET 10 Gbs 10 ps 1176ps/nm Ethernet 10 Gbs 5 ps 738 ps/nm SONET 40 Gbs 2.5 ps 64 ps/nm

23. Link Network Characterization Link Characterization – It measures the fiber performance and the quality of any interconnections – The suite of tests mostly depend on the user’s methods and procedures – It could be uni-directional or bi- Network Characterization – It provides the network baseline measurements before turning the transmission system up. – Network Characterization includes measurements through the optical amplifiers, dispersion compensators, and any elements in line. – It is a limited suite of tests as compared to Link Characterization © 2007 JDSU. All rights reserved. 23 – It could be uni-directional or bi- directional – Tests – Connector Inspection, IL, ORL, OTDR, PMD, CD, AP compared to Link Characterization Point B Point A CWDM/DWDM Optical Network Optical Amp. Video Headend DWD M Optica l Netwo rk ROADM Optical Amplifier Router

24. Testing the Fiber Plant Connector inspection Insertion Loss OTDR Optical Return Loss Polarization Mode Dispersion (PMD) Chromatic dispersion (CD) Attenuation profile (AP) @ On @ Charge LASER ON/OFF PREV LEVEL ADJUST MENU ENTER CW/ FMOD ☼ LASER ON/OFF PREV LEVEL ADJUST MENU ENTER CW/ FMOD ☼ ☼

26. Inspect, Clean, Inspect, and Go! Fiber inspection and cleaning are SIMPLE steps with immense benefits. 4 4 Connect 2 2 Clean 1 1 Inspect 3 3 Inspect © 2007 JDSU. All rights reserved. 26 ■ If the fiber is clean, CONNECT the connector. NOTE: Be sure to inspect both sides (patch cord “male” and bulkhead “female”) of the fiber interconnect. ■ If the fiber is dirty, use a simple cleaning tool to CLEAN the fiber surface. ■ Use a probe microscope to INSPECT the fiber. – If the fiber is dirty, go to step 2, cleaning. – If the fiber is clean, go to step 4, connect. ■ Use a probe microscope to RE-INSPECT (confirm fiber is clean). – If the fiber is still dirty, go back to step 2, cleaning. – If the fiber is clean, go to step 4, connect.

27. Measuring Insertion Loss The insertion loss measurement over a complete link requires a calibrated source and a power meter. This is a unidirectional measurement, however could be performed bi-directionally for operation purposes Calibrated Light Source Optical power meter © 2007 JDSU. All rights reserved. 27 Calibrated Light Source d B m W M e n u Ca nc el d B 2s Perm Optical power meter d B m W d B Pt Pr This measurement is the most important test to be performed, as each combination of transmitter/receiver has a power range limit. It is the difference between the transmitted power and the received power at the each end of the link

28. Measuring Optical Return Loss Different methods available The 2 predominant test methods: – Optical Continuous Wave Reflectometry (OCWR) • A laser source and a power meter, using the same test port, are connected to the fiber under test. – Optical Time Domain Reflectometry (OTDR) © 2007 JDSU. All rights reserved. 28 OCWR method – Optical Time Domain Reflectometry (OTDR) • The OTDR is able to measure not only the total ORL of the link but also section ORL (cursor A – B) OTDR method

29. Optical Time Domain Reflectometer (OTDR) OTDR depends on two types of phenomena: - Rayleigh scattering - Fresnel reflections. © 2007 JDSU. All rights reserved. 29 Rayleigh scattering and backscattering effect in a fiber Light reflection phenomenon = Fresnel reflection

30. How does OTDR work ? An Optical Time Domain Reflectometer (OTDR) operates as one-dimensional radar allowing for complete scan of the fiber from only one end. The OTDR injects a short pulse of light into one end of the fiber and analyzes the backscatter and reflected signal coming back The received signal is then plotted into a backscatter X/Y display in dB vs. distance Event analysis is then performed in order to populate the table of results. OTDR Block Diagram Example of an OTDR trace © 2007 JDSU. All rights reserved. 30 OTDR Block Diagram Example of an OTDR trace Distance Fiber under test

31. Optical Time Domain Reflectometer (OTDR) Detect, locate, and measure events at any location on the fiber link © 2007 JDSU. All rights reserved. 31 Fusion Splice Connector or mechanical Splice Gainer • OTDR tests are often performed in both directions and the results are averaged, resulting in bi-directional event loss analysis. • OTDRs most commonly operate at 1310, 1550 and 1625 nm singlemode wavelengths. Macrobend Fiber end or break

32. Contamination and Signal Performance Fiber Contamination and Its Effect on Signal Performance CLEAN CONNECTION Back Reflection = -67.5 dB Total Loss = 0.250 dB 1 1 © 2007 JDSU. All rights reserved. 32 Total Loss = 0.250 dB DIRTY CONNECTION Back Reflection = -32.5 dB Total Loss = 4.87 dB 3 3 Clean Connection vs. Dirty Connection This OTDR trace illustrates a significant decrease in signal performance when dirty connectors are mated.

33. 10 seconds PMD Light Source Measuring PMD Different PMD standards describing test methods • IEC 60793-1-48/ ITU-T G.650.2/ EIA/TIA Standard FOTP-XXX The broadband source sends a polarized light which is analyzed by a spectrum analyzer after passing through a polarizer PMD Receiver © 2007 JDSU. All rights reserved. 33 ps by a spectrum analyzer after passing through a polarizer The PMD measurement range should be compatible the transmission bit rate. In order to cover a broad range of field applications, it should be able to measure between 0.1 ps and 60 ps. PMD measurement is typically performed unidirectional. When PMD results are too close to the system limits, it may be required to perform a long term measurement analysis in order to get a better picture of the variation over the time.

34. Dealing with PMD PMD constraints increase with: – Channel Bit rate – Fiber length (number of sections) – Number of channels (increase missing channel possibility) PMD decreases with: – Better fiber manufacturing control (fiber geometry…) © 2007 JDSU. All rights reserved. 34 – Better fiber manufacturing control (fiber geometry…) – PMD compensation modules. PMD is more an issue for old G652 fibers (1996) than newer fibers At any given signal wavelength the PMD is an unstable phenomenon, unpredictable. So has to be measured

35. Measuring CD There are different methods to measure the chromatic dispersion. IEC 60793- 1-42 / ITU-T G650.1; EIA/TIA-455- FOTP-175B The Phase Shift method is the most versatile one. It requires a source (broadband or narrow band) and a receiver (phase meter) to be connected to each end of the link The Chromatic dispersion measurement will be performed over a given CD Light Source CD Receiver © 2007 JDSU. All rights reserved. 35 The Chromatic dispersion measurement will be performed over a given wavelength range and results will be correlated to the transmission system limits according to the bit rate being implemented. Parameters to be controlled in such way to correlate to the equipment specifications: – Total link dispersion. – Dispersion slope – Zero dispersion wavelength and associated slope

36. Measuring AP Every fiber presents varying levels of attenuation across the transmission spectrum. The purpose of the AP measurement is to represent the attenuation as a function of the wavelength. A reference measurement of the source and fiber jumpers is required prior to performing the Water peak Broadband Light Source Narrowband Receiver © 2007 JDSU. All rights reserved. 36 jumpers is required prior to performing the measurements. The receiver records the attenuation per wavelength of the source used for transmission. This could be used to determine amplifier locations and specifications, and could have an impact on channel equalization (macro or micro-bends). Spectral attenuation measurements are typically performed unidirectional. The wavelength measurement range should be at least equivalent to transmission system: C-band or C+L band. IEC 60793-1-1 Optical fibers – Part 1-1: Generic Specification – GeneralTest procedure ITU-T G.650.1 C+L DWDM Band AP results

38. Wrap Up

39. The Tools for Installing Maintaining Networks Fiber Links Inspection Cleaning Loss/ ORL Test sets OTDR Dispersion testers (PMD and CD) Attenuation Profile testers Network / Transport © 2007 JDSU. All rights reserved. 39 Network / Transport Inspection Cleaning Power Meters Ethernet Testers BER Testers Optical Spectrum Analyzers Network Characterization (System Total Dispersion)

40. QA and Resources Questions Contacts Name - Company (Title) Phone E-mail Fred Ingerson – 4th Wave (JDSU Mfg Rep) (315) 436-0895 fred@4th-wave.com Mark Leupold – JDSU (MSO Acct Mgr) (540) 226-6284 mark.leupold@jdsu.com © 2007 JDSU. All rights reserved. 40 Mark Leupold – JDSU (MSO Acct Mgr) (540) 226-6284 mark.leupold@jdsu.com John Swienton – JDSU (FO App Specialist) (413)231-2077 john.swienton@jdsu.com Greg Lietaert – JDSU (FO Prod Line Mgr) (240) 404 2517 gregory.lietaert@jdsu.com Tim Yount – JDSU (FO Test Mkt Mgr) (207)329-3342 tim.yount@jdsu.com For more on Fiber Characterization visit: www.jdsu.com/characterization There you’ll find… Technical Posters, White Papers, Quick Start Guides, FO Guidebooks, Product and Service Information, and more…

101483423-Fiber-Characterization-Training.pdf

101483423-Fiber-Characterization-Training.pdf

Recommandé

Contenu connexe

Similaire à 101483423-Fiber-Characterization-Training.pdf

Similaire à 101483423-Fiber-Characterization-Training.pdf(20)

Plus de Mohamedshabana38

Plus de Mohamedshabana38(20)

Dernier

Dernier(20)

101483423-Fiber-Characterization-Training.pdf