| W: Abbreviation for Watt. A linear measurement
of optical power, usually expressed in milliwatts, microwatts, and nanowatts. |
| WAN: See Wide Area Network. |
Waveguide: A material
medium that confines and guides a propagating
electromagnetic wave. In the microwave regime,
a waveguide normally consists of a hollow
metallic conductor, generally rectangular,
elliptical, or circular in cross-section.
This type of waveguide may, under certain
conditions, contain a solid or gaseous dielectric
material. In the optical regime, a waveguide
used as a long transmission line consists
of a solid dielectric filament
(fiber), usually circular
in cross-section. In integrated optical circuits an optical waveguide may consist of a thin
dielectric film. In the RF regime, ionized
layers of the stratosphere and the refractive
surfaces of the troposphere may also serve
as a waveguide. |
| Waveguide
Coupler: A coupler in which light
gets transferred between planar waveguides. |
| Waveguide
Dispersion: The part of chromatic dispersion arising from the different speeds light travels
in the core and cladding of a single-mode
fiber (i.e., from the fiber’s waveguide
structure). |
|
| Wavelength: The distance
between points of corresponding phase of two
consecutive cycles of a wave. The wavelength
relates to the propagation velocity, and the
frequency, by: |
Wavelength =
Propagation Velocity / Frequency |
Wavelength Adapter: A device which receives
one wavelength and outputs a second wavelength,
usually to take a standard signal and convert
it to an ITU wavelength. |
| Wavelength-division Multiplexing (WDM): Sending several signals through one fiber with different
wavelengths of light. |
 |
| Wavelength
Isolation: A WDM’s isolation of
a light signal in the desired optical channel
from the unwanted optical channels. Also called
far-end crosstalk. |
| Wavelength
Routing Switch (WRS): A switch, used
in optical networks, that routes
wavelengths as required to specific terminals
in the network. |
| Wavelength
Selective Coupler: A device which
couples the pump laser wavelength
to the optical fiber while
filtering out all other unwanted wavelengths.
Used in erbium-doped fiber amplifiers. |
| Wavelength
Stability: The maximum deviation of
the peak wavelength of an optical source from its average
wavelength. |
| WDM: See wavelength-division multiplexing. |
| Weather
Fade: In satellite systems, the loss
of a satellite signal due to extremely heavy
(and generally very localized) rain, snow,
or other extreme weather. |
| Wide Area
Network (WAN): A
physical or logical network that provides
capabilities for a number of independent devices
to communicate with each other over a common
transmission-interconnected topology in geographic
areas larger than those served by local area networks or metropolitan area networks. |
 |
| Wideband: Possessing
large bandwidth. |
| Wireless: A network or terminal that uses electromagnetic
waves, such as RF, infrared, laser, visible
light, and acoustic energy, not wires,
for telecommunications. |
| WWW
(World Wide Web) : The collection of millions of graphical pages
that heavily utilize HTML to provide access
to information. One of the key components
of the Internet. |
