Fiber U Basics

Lesson #5, Optical Fiber
FOA Reference Guide To Fiber Optics
And Study Guide To FOA Certification

FOA Reference Guide to Fiber Optics

Answers To Chapter Questions

Chapter 5 Quiz-Fiber


    1.    ANS:    A
Singlemode fiber cores are much smaller than multimode fibers so they only can carry one mode of light.

    2.    ANS:    B
Typical singlemode fiber has a core size around 9 microns.

    3.    ANS:    A
Since it carries only one mode, SM fiber suffers no modal dispersion which limits MM fiber and has much higher bandwidth.

    4.    ANS:    B
MM fiber operates at 850 and 1300 nm, while singlemode fiber is optimized for 1310 and 1550 nm.

    5.    ANS:    A
OM2 and OM3 (laser-optimized) fiber has a 50 micron core.

    6.    ANS:    A
Attenuation of the fiber contributes to the loss of the cable plant, along with connector losses.

    7.    ANS:    B
Scattering is the major cause of fiber attenuation.

    8.    ANS:    A
Most POF is large core step-index fiber, with a core ~1mm.

    9.    ANS:    A
Scattering is higher at shorter wavelengths, causing fiber attenuation of about 3 dB/km at 850 nm but only 1 dB/km at 1300 nm. MM fiber is rarely used at 1550 nm.

    10.    ANS:    C
Chromatic dispersion, caused by the fact that the speed of light in glass is a function of wavelength, affects both SM and MM fiber.

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