Page 21 - Optical Switching And Networking Handbook

6 Chapter 1

Receiver A receiver is an electronic device that converts optical
signals to electrical signals. Your antenna receives radio signals.
A fiberoptic receiver—usually an electronics component called a
diode—similarly receives light signals.

Single-mode fiber This type of fiber is used typically for long dis-
tances. Single-mode fiber is optical fiber that is designed for the
transmission of a single ray or mode of light as a carrier and is used
for long-distance signal transmission. Single-mode fiber has a much
smaller core than multimode fiber.

Time-division multiplexing (TDM) A scheme in which numer-
ous signals are combined for transmission on a single communica-
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tions line or channel. Each signal is broken up into many segments,
each having very short duration. The circuit that combines signals
at the transmitting end of a communications link is known as a mul-
tiplexer. It accepts the input from each individual end user, breaks
each signal into segments, and assigns the segments to the compos-
ite signal in a rotating, repeating sequence. The composite signal
thus contains data from all the end users. At the other end of the
long-distance cable, the individual signals are separated out by
means of a circuit called a demultiplexer and routed to the proper
end users. Think of a road system where you have a six-lane high-
way. Suddenly you come to a single-lane bridge. Protocol states that
politely, each lane will in turn enable one vehicle to cross the bridge.
Therefore, each input (lane) grabs the entire bandwidth (the lane)
and passes its traffic (the cars) one at a time. This is shown in Fig-
ure 1-5 with the single-lane bridge analogy.

Transmitter Just as a radio transmitter sends out radio signals,
an optical transmitter—usually a light-emitting diode (LED) or a
laser—sends out optical signals.

Wavelength-division multiplexer (WDM) A fiberoptic device
used to separate signals of different wavelengths carried on one

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