Lesson 3: Physical Layer Cabling: Fiber Optics

Question 1

Absorption

Answer 1

Light interaction with the atomic structure of the fiber material; also involves the conversion of optical power to heat

Question 2

Backbone

Answer 2

Main fiber distribution. The primary path for data traffic to and from destinations and sources in the campus network

Question 3

Cladding

Answer 3

Material surrounding the core, which must have a lower index of refraction to keep the light in the core

Question 4

Dense Wavelength Division Multiplex (DWDM)

Answer 4

Incorporates the propagation of several wavelengths in the 1550 nm range for a single fiber

Question 5

Dispersion

Answer 5

Broadening of a light pulse as it propagates through a fiber strand

Question 6

Dispersion Compensating Fiber

Answer 6

Acts like an equalizer, canceling dispersion effects and yielding close to zero dispersion in the 1550 nm region

Question 7

Distributed Feedback (DFB) Laser

Answer 7

A more stable laser suitable for use in DWDM systems

Question 8

DL

Answer 8

Diode laser

Question 9

Fiber Bragg Grating

Answer 9

A short strand of modified fiber that changes the index of refraction and minimizes intersymbol interference

Question 10

Fiber Cross-connect

Answer 10

Optical patch panel used to interconnect fiber cables

Question 11

Fiber, Light Pipe, Glass

Answer 11

Terms used to describe a fiber-optic strand

Question 12

FTTB

Answer 12

Fiber to the Business

Question 13

FTTC

Answer 13

Fiber to the Curb

Question 14

FTTD

Answer 14

Fiber to the Desktop

Question 15

FTTH

Answer 15

Fiber to the Home

Question 16

Fusion Splicing

Answer 16

A long-term method where two fibers are fused or welded together

Question 17

GBIC

Answer 17

Gigabit interface converter

Question 18

Graded-index Fiber

Answer 18

The index of refraction is gradually varied with a parabolic profile

Question 19

IC

Answer 19

Interconnect fibers branch exchange—item D shows the jumpers connecting the main fiber cross-connect (item B) to the active equipment (item C)

Question 20

IDC

Answer 20

Intermediate distribution closet

Question 21

Index-matching Gel

Answer 21

A jellylike substance that has an index of refraction much closer to glass than to air

Question 22

Infrared Light

Answer 22

Light extending from 680 nm up to the wavelengths of the microwaves

Question 23

Isolator

Answer 23

An inline passive device that allows optical power to flow only in one direction

Question 24

LED

Answer 24

Light-emitting diode

Question 25

Logical Fiber Map

Answer 25

Shows how the fiber is interconnected and data is distributed throughout a campus

Question 26

Long-Haul

Answer 26

The transmission of data over hundreds or thousands of miles

Question 27

Macrobending

Answer 27

Loss due to light breaking up and escaping into the cladding

Question 28

Mechanical Splices

Answer 28

Two fibers joined together with an air gap, thereby requiring an index-matching gel to provide a good splice

Question 29

Microbending

Answer 29

Loss caused by very small mechanical deflections and stress on the fiber

Question 30

mm

Answer 30

Multimode

Question 31

Mode Field Diameter

Answer 31

The actual guided optical power distribution, which is typically a micron or so larger than the core diameter; single-mode fiber specifications typically list the mode field diameter

Question 32

Multimode Fiber

Answer 32

A fiber that supports many optical waveguide modes

Question 33

Numerical Aperture

Answer 33

A measure of a fiber's ability to accept light

Question 34

Optical Ethernet

Answer 34

Ethernet data running over a fiber link

Question 35

Optical Spectrum

Answer 35

Light frequencies from the infrared on up

Question 36

Physical Fiber Map

Answer 36

Shows the routing of the fiber but also shows detail about the terrain, underground conduit, and entries into buildings

Question 37

Pulse Dispersion

Answer 37

Stretching of received pulse width because of multiple paths taken by the light

Question 38

Received Signal Level (RSL)

Answer 38

The input signal level to an optical receiver

Question 39

Refractive Index

Answer 39

Ratio of the speed of light in free space to its speed in a given material

Question 40

Scattering

Answer 40

Caused by refractive index fluctuations; accounts for 96 percent of attenuation loss

Question 41

SFP

Answer 41

Small Form Pluggable

Question 42

Single-mode Fiber

Answer 42

Fiber cables with core diameters of about 7-10 µm; light follows a single path

Question 43

sm

Answer 43

Single mode

Question 44

SONET/SDH

Answer 44

Synchronous optical network; protocol standard for optical transmission in long-haul communication/synchronous digital hierarchy

Question 45

STS

Answer 45

Synchronous transport signals

Question 46

Tunable Laser

Answer 46

Laser in which the fundamental wavelength can be shifted a few nanometers, ideal for traffic routing in DWDM systems

Question 47

Vertical Cavity Surface Emitting Lasers (VCSELs)

Answer 47

Lasers with the simplicity of LEDs and the performance of lasers

Question 48

XENPAK, XPAK, X2, XFP, SFP+

Answer 48

The ten gigabit interface adapter

Question 49

Zero-dispersion Wavelength

Answer 49

Point where the dispersion is actually zero