Lesson 3: Physical Layer Cabling: Fiber Optics Flashcards
Absorption
Light interaction with the atomic structure of the fiber material; also involves the conversion of optical power to heat
Backbone
Main fiber distribution. The primary path for data traffic to and from destinations and sources in the campus network
Cladding
Material surrounding the core, which must have a lower index of refraction to keep the light in the core
Dense Wavelength Division Multiplex (DWDM)
Incorporates the propagation of several wavelengths in the 1550 nm range for a single fiber
Dispersion
Broadening of a light pulse as it propagates through a fiber strand
Dispersion Compensating Fiber
Acts like an equalizer, canceling dispersion effects and yielding close to zero dispersion in the 1550 nm region
Distributed Feedback (DFB) Laser
A more stable laser suitable for use in DWDM systems
DL
Diode laser
Fiber Bragg Grating
A short strand of modified fiber that changes the index of refraction and minimizes intersymbol interference
Fiber Cross-connect
Optical patch panel used to interconnect fiber cables
Fiber, Light Pipe, Glass
Terms used to describe a fiber-optic strand
FTTB
Fiber to the Business
FTTC
Fiber to the Curb
FTTD
Fiber to the Desktop
FTTH
Fiber to the Home
Fusion Splicing
A long-term method where two fibers are fused or welded together
GBIC
Gigabit interface converter
Graded-index Fiber
The index of refraction is gradually varied with a parabolic profile
IC
Interconnect fibers branch exchange—item D shows the jumpers connecting the main fiber cross-connect (item B) to the active equipment (item C)
IDC
Intermediate distribution closet
Index-matching Gel
A jellylike substance that has an index of refraction much closer to glass than to air
Infrared Light
Light extending from 680 nm up to the wavelengths of the microwaves
Isolator
An inline passive device that allows optical power to flow only in one direction
LED
Light-emitting diode
Logical Fiber Map
Shows how the fiber is interconnected and data is distributed throughout a campus
Long-Haul
The transmission of data over hundreds or thousands of miles
Macrobending
Loss due to light breaking up and escaping into the cladding
Mechanical Splices
Two fibers joined together with an air gap, thereby requiring an index-matching gel to provide a good splice
Microbending
Loss caused by very small mechanical deflections and stress on the fiber
mm
Multimode
Mode Field Diameter
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
Multimode Fiber
A fiber that supports many optical waveguide modes
Numerical Aperture
A measure of a fiber’s ability to accept light
Optical Ethernet
Ethernet data running over a fiber link
Optical Spectrum
Light frequencies from the infrared on up
Physical Fiber Map
Shows the routing of the fiber but also shows detail about the terrain, underground conduit, and entries into buildings
Pulse Dispersion
Stretching of received pulse width because of multiple paths taken by the light
Received Signal Level (RSL)
The input signal level to an optical receiver
Refractive Index
Ratio of the speed of light in free space to its speed in a given material
Scattering
Caused by refractive index fluctuations; accounts for 96 percent of attenuation loss
SFP
Small Form Pluggable
Single-mode Fiber
Fiber cables with core diameters of about 7-10 µm; light follows a single path
sm
Single mode
SONET/SDH
Synchronous optical network; protocol standard for optical transmission in long-haul communication/synchronous digital hierarchy
STS
Synchronous transport signals
Tunable Laser
Laser in which the fundamental wavelength can be shifted a few nanometers, ideal for traffic routing in DWDM systems
Vertical Cavity Surface Emitting Lasers (VCSELs)
Lasers with the simplicity of LEDs and the performance of lasers
XENPAK, XPAK, X2, XFP, SFP+
The ten gigabit interface adapter
Zero-dispersion Wavelength
Point where the dispersion is actually zero
