Fiber U Self Study

Fiber Characterization For Long Haul and High Speed Networks

fiber characterization

Objectives: From this self-study lesson you should learn:
  • Which networks may require fiber characterization
  • What are Chromatic Dispersion (CD) and Polarization Mode Dispersion (PMD)
  • How CD and PMD affect high speed long distance transmission
  • What is Spectral Attenuation (SA)
  • How SA affects wavelength-division multiplexing
  • How one tests CD, PMD and SA

Fiber U Fiber Optic Testing self-study course or equivalent


One of the big advantages of fiber optics is its capability for long distance high-speed communications. Singlemode fiber attenuation at long wavelengths (~1550 nm) is extremely low. Fibers can be fusion spliced with virtually no loss. High-powered lasers, sophisticated transmission protocols and fiber amplifiers mean long distances are easily obtained. Dense wavelength division multiplexing (DWDM) allows up to 128 channels of signals on a single fiber.

However, for high-speed networks operating over very long distances, new factors limiting fiber performance become important. Chromatic dispersion, the dispersion caused by light of different wavelengths, and polarization mode dispersion, caused by the polarization of the light in the fiber, become factors limiting the bandwidth capacity of fiber links. Pulse broadening due to chromatic dispersion and the variation of fiber attenuation with wavelength can become issues with DWDM.

All these factors need testing on long distance networks to ensure proper link performance. Tests are performed on new installations to ensure the fiber being installed is capable of future upgrades. Older cable plants are tested to evaluate fibers for upgrades of legacy communications systems at slower speeds.

A suite of tests for these factors has been developed to test fibers for long distance high-speed networks. These tests are normally called “fiber
characterization,” but technically they are “fiber optic cable plant characterization” since it must include the complete end-to-end cable plant. That is what this course will cover.
The course leads you to read online or printed materials (with an emphasis on the online using the FOA Guide), watch FOA YouTube Videos, complete some activities and take the quizzes. Each lesson plan will be self-contained. Lesson plans open in new pages so the course overview page stays open to lead you to the next lesson or you may use the link at the bottom of the page.

Student Assignment

Read the references, watch the videos and take the quiz (Test Your Knowledge)

FOA YouTube Videos,
FOA Lecture 20: Other Fiber Optic Tests  (This video covers reflectance, bandwidth, PMD and CD for long haul SM systems and spectral attenuation for WDM systems.)

FOA Lecture 28, Fiber Characterization   (Testing long distance high speed networks)

Online FOA Guide
FOA Reference Guide to Fiber Optics
Testing long haul networks (CD, PMD, Spectral Attenuation)  (Note links to other relevant pages in the FOA Guide page.)

Reference Textbook
FOA Reference Guide to Fiber Optic Testing, Chapter 10  

FOA Textbook on fiber optic testing

Test Your Knowledge
Online Quiz  

FOA Certification
If you have a CFOT and appropriate experience, this course will help prepare you for the FOA CFOS/T specialist certification.

Fiber U Certificate
Get a "Fiber U Certificate of Completion" When You Complete The Course
After you complete the Fiber U Fiber Optic Testing online self-study course, you can now take an online exam and, when you pass the exam, get a "Certificate of Completion" for this course. You should complete all lessons including taking the quiz ("Test Your Comprehension") at the end of every lesson. When you think you are prepared, you can take an online exam for a nominal fee ($20) which will give you a "Certificate of Completion" for this course.

If you are working on FOA certification, print out (PDF) your completed case studies from Lesson 8 and save along with your Fiber U Certificate of Completion for your application for certification.

When you are ready, go here to take the Fiber U Fiber Characterization Certificate of Completion Exam  

Please note: receiving this Fiber U Certificate of Completion does not include FOA certification or membership but it does become documentation of your knowledge of fiber optics and should be part of your portfolio of documented knowledge, other training and work experience that can qualify you to apply for FOA direct CFOT certification through the FOA "Work to Cert" program.

Read more about the Fiber U Certificate of Completion program including detail directions on taking the exam.

For more information on the FOA and its certification programs, go to the FOA page on certification.

For information on the FOA "Work to Cert" direct certification program for those with industry experience, go here.


Table of Contents: The FOA Reference Guide To Fiber Optics

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