Page 297 - Optical Switching And Networking Handbook

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282 Glossary

Lambda (l) An optical wavelength.
Laser An acronym for light amplification by the stimulated
emission of radiation. A light source that produces, through
stimulated emission, coherent, near-monochromatic light. Lasers
in fiber optics are usually solid-state semiconductor types.
Light In a strict sense, the region of the electromagnetic spec-
trum that can be perceived by human vision, designated by the
visible spectrum, and nominally covering the wavelength range
of 0.4 m to 0.7 m. In the laser and optical communication
fields, custom and practice have extended usage of the term to
include the much broader portion of the electromagnetic spec-
trum that can be handled by the basic optical techniques used
for the visible spectrum. This region has not been clearly
defined. Athough, as employed by most workers in the field, it
may be considered to extend from the near ultraviolet region of
approximately 0.3 m, through the visible region, and into the
mid-infrared region to 30 m.
Lightpath Analogous to virtual circuits in the ATM world, a
lightpath is a virtual circuit in the optical domain that could con-
sist of multiple spans, each using a different physical wavelength
for the transmission of information across an optical network.
Line One or more SONET sections, including network elements
at each end, capable of accessing, generating, and processing
Line Overhead.
Line Terminating Equipment (LTE) Network elements such
as add/drop multiplexers or digital cross-connect systems that
can access, generate, and process Line Overhead.
Megabits per second (Mbps) One million bits per second.
Metropolitan Area Network (MAN) A network covering
an area larger than a local area network (LAN); a wide area
network (WAN) covering a metropolitan area. Usually, it is an
interconnection of two or more LANs.

Micrometer One millionth of a meter. Abbreviated m.