F: Abbreviation for
Fahrenheit. Measure of temperature where pure water freezes at 32?and
boils at 212? |
| Fabry Perot: See FP. |
Failure
Rate: See FIT
Rate. |
Fall
Time: Also called turn-off time. The time required for the
trailing edge of a pulse to fall from 90% to 10% of its amplitude; the
time required for a component to produce such a result. Typically measured
between the 90% and 10% points or alternately the 80% and 20%
points. |
 |
FAR: Abbreviation for
federal acquisition regulation. The guidelines by which the U.S.
government purchases goods and services. Also the criteria that must be
met by the vendor in order to be considered as a source for goods and
services purchased by the U.S. government. |
Faraday
Effect: A phenomenon that causes some materials to rotate the polarization of light in the presence of a magnetic field parallel to the direction of
propagation. Also called magneto-optic effect. |
Far-End
Crosstalk: See wavelength
isolation. |
FBG: Abbreviation for fiber
Bragg gratings. See Bragg
grating. |
FCC: Abbreviation for
Federal Communications Commission. The U.S. Government board
of five presidential appointees that has the authority to regulate all
non-Federal Government interstate telecommunications as well as all
international communications that originate or terminate in the United
States. |
http://www.fcc.gov |
FC/PC: See FC. A threaded
optical connector that uses a special curved polish on the connector for
very low backreflection.
Good for single-mode or multimode fiber. |
 |
FCS: Abbreviation
for frame check sequence. An error-detection scheme that (a) uses parity
bits generated by polynomial encoding of digital signals, (b) appends
those parity bits to a digital signal, and (c) uses decoding algorithms
that detect errors in the received digital signal. |
FDA: Abbreviation for Food
and Drug Administration. Organization responsible for, among other things,
laser safety. |
http://www.fda.gov |
FDDI: Abbreviation for
fiber distributed data interface. 1) A dual counter-rotating ring local
area network. 2) A connector used in a dual counter-rotating ring
local area network (illustrated). |
 |
FDM: See frequency-division
multiplexing. |
FEC: See forward
error correcting. |
| Feeder: 1) Supplies the
input of a system, subsystem, or equipment, such as a transmission line or
antennae. 2) A coupling device between an antennae and its transmission
line. 3) A transmission facility between either the point of origin of the
signal or at the head-end of a distribution facility. |
| Ferrule: A rigid tube
that confines or holds a fiber as part of a connector assembly. |
 |
| FET: Abbreviation for field-effect transistor. A semiconductor so
named because a weak electrical signal coming in through one electrode
creates an electrical field through the rest of the transistor. This field
flips from positive to negative when the incoming signal does, and
controls a second current traveling through the rest of the transistor.
The field modulates the second current to mimic the first one, but it can
be substantially larger. |
Fiber Fuse: A mechanism
whereby the core of a single-mode
fiber can be destroyed at high optical power levels.
|
 |
| Fiber
Grating: An optical fiber in which the refractive index of
the core varies periodically along its length, scattering light in a way
similar to a diffraction grating, and transmitting or reflecting certain
wavelengths selectively. |
 |
| Fiber-in-the-loop (FITL): Fiber optic service to a node that is located in a
neighborhood. |
| Fiber Optic
Attenuator: A component installed in a fiber optic
transmission system that reduces the power in the optical signal. It is
often used to limit the optical power received by the photodetector to within the limits of the optical receiver. A fiber optic attenuator may
be an external device, separate from the receiver, or incorporated into
the receiver design as illustrated (far left). |
 |
| Fiber Optic
Cable: A cable containing one or more optical
fibers. |
| Fiber Optic Communication
System: The transfer of modulated or unmodulated optical
energy through optical fiber media which terminates in the same or
different media. |
| Fiber Optic
Link: A transmitter, receiver,
and cable
assembly that can transmit information between two points. |
 |
| Fiber Optic
Span: An optical
fiber/cable terminated at both ends which may include devices that
add, subtract, or attenuate optical signals. |
| Fiber Optic
Subsystem: A functional entity with defined bounds and
interfaces which is part of a system. It contains solid state and/or other
components and is specified as a subsystem for the purpose of trade and
commerce. |
 |
| Fiber-to-the-Curb (FTTC): Fiber optic
service to a node connected by wires to several nearby homes, typically on
a block. |
 |
| Fiber-to-the-Home (FTTH): Fiber optic service to a node located inside an
individual home. |
| Fibre Channel: An industry-standard specification that originated in Great
Britain which details computer channel communications over fiber optics at
transmission speeds from 132 Mb/s to 1062.5 Mb/s at distances of up to 10
kilometers. |
| Filter: A device which
transmits only part of the incident energy and may thereby change the
spectral distribution of energy. |
 |
| FIT Rate: Number of device failures in one billion device hours. |
| Fluoride
Glasses: Materials that have the amorphous structure of glass
but are made of fluoride compounds (e.g., zirconium fluoride) rather than
oxide compounds (e.g., silica). Suitable for very long wavelength
transmission. This material tends to be destroyed by water, limiting its
use. |
| FM (Frequency Modulation): A method of transmission in which the carrier frequency varies in
accordance with the signal. |
 |
| Forward
Error Correcting (FEC): A communication technique used to
compensate for a noisy transmission channel. Extra information is sent
along with the primary data payload to correct for errors that occur in
transmission. |
 |
| FOTP (Fiber Optic Test
Procedure): Standards developed and published by the Electronic Industries
Association (EIA) under the EIA-RS-455 series of standards. |
| Four Wave Mixing
(FWM): A nonlinearity common in DWDM systems where multiple wavelengths mix together to form new wavelengths,
called interfering products. Interfering products that fall on the
original signal wavelength become mixed with the signal, mudding the
signal, and causing attenuation. Interfering products on either side of
the original wavelength can be filtered out. FWM is most prevalent near
the zero-dispersion
wavelength and at close wavelength spacings. |
 |
| FP: Abbreviation for
Fabry-Perot. Generally refers to any device, such as a type of laser
diode, that uses mirrors in an internal cavity to produce multiple
reflections. |
| Free-Space Optics: Also called free-space
photonics. The transmission of modulated visible or infrared (IR) beams through the atmosphere via lasers, LEDs,
or IR-emitting
diodes (IREDs) to obtain broadband communications. |
| Frequency-division Multiplexing (FDM): A method of deriving two or more simultaneous, continuous
channels from a transmission medium by assigning separate portions of the
available frequency spectrum to each of the individual channels. |
| Frequency-shift Keying (FSK): Frequency modulation in which the modulating signal shifts the
output frequency between predetermined values. Also called frequency-shift
modulation, frequency-shift signaling. |
| Frequency Stacking: The process that
allows two identical frequency bands to be sent over a single cable by up converting one of the frequencies and "stacking" it with the
other. |
| Fresnel
Reflection Loss: Reflection losses at the ends of fibers
caused by differences in the refractive
index between glass and air. The maximum reflection caused by a
perpendicular air-glass interface is about 4% or about -14 dB. |
FSAN: Abbreviation for
full service access network. A forum for the world’s largest
telecommunications services providers and equipment suppliers to work
define broadband access networks based primarily on the ATM passive
optical network structure. |
http://www.fsanet.net/ |
| Full-duplex Transmission: Simultaneous bidirectional transfer of data. |
 |
| Fused
Coupler: A method of making a multimode or single-mode coupler by wrapping fibers together, heating them, and pulling them to form a
central unified mass so that light on any input fiber is coupled to all
output fibers. |
 |
| Fused Fiber: A bundle of fibers fused together so they maintain a fixed
alignment with respect to each other in a rigid rod. |
| Fusion Splicer: An instrument that permanently bonds two fibers together by
heating and fusing them. |
 |
| FUT: Abbreviation for fiber
under test. Refers to the fiber being measured by some type of test equipment. |
| FWHM: Abbreviation for
full width half maximum. Used to describe the width of a spectral emission
at the 50% amplitude points. Also known as FWHP (full width half
power). |
 |
| FWM: See four wave
mixing. |
