20
1 Perspectives on Lightwave Communications
Optical
transmitter
Optical
receiver
Passive or active optical devices
(optical filters, couplers, switches)
Cabled optical fibers
Optical amplifier
Information
sources
Optical connecters
Information
recipients
Video
Audio
Data
Video
Audio
Data
Fig. 1.10 Main constituents of an optical fiber communications link
consisting of a photodetector plus amplification and signal-restoring circuitry. Additional components include optical amplifiers, connectors, splices, couplers, regenerators (for restoring the signal-shape characteristics), and other passive components
and active photonic devices.
The cabled fiber is one of the most important elements in an optical fiber link
as is described in Chaps. 2 and 3. In addition to protecting the glass fibers during
installation and service, the cable may contain copper wires for powering optical
amplifiers or signal regenerators, which are needed periodically in long-distance
links for amplifying and reshaping the signal. A variety of fiber types with different
performance characteristics exist for a wide range of applications. To protect the glass
fibers during installation and service, there are many different cable configurations
depending on whether the cable is to be installed inside a building, underground
in ducts or through direct-burial methods, outside on poles, or under water. Very
low-loss optical connectors and splices are needed in all categories of optical fiber
networks for joining cables and for attaching one fiber to another.
Analogous to copper cables, the installation of optical fiber cables can be either
aerial, in ducts, undersea, or buried directly in the ground, as illustrated in Fig. 1.11.
As Chap. 2 describes, the cable structure will vary greatly depending on the specific
application and the environment in which it will be installed. Owing to installation and/or manufacturing limitations, individual cable lengths for in-building or
terrestrial applications will range from several hundred meters to several kilometers.
Practical considerations such as reel size and cable weight determine the actual length
of a single cable section. The shorter segments tend to be used when the cables are
pulled through ducts. Longer lengths are used in aerial, direct-burial, or underwater
applications.
Workers can install optical fiber cables by pulling or blowing them through ducts
(both indoor and outdoor), laying them in a trench outside, plowing them directly
into the ground, suspending them on poles, or laying or plowing them underwater.
Although each method has its own special handling procedures, they all need to
adhere to a common set of precautions. These include avoiding sharp bends of the
1 Perspectives on Lightwave Communications
Optical
transmitter
Optical
receiver
Passive or active optical devices
(optical filters, couplers, switches)
Cabled optical fibers
Optical amplifier
Information
sources
Optical connecters
Information
recipients
Video
Audio
Data
Video
Audio
Data
Fig. 1.10 Main constituents of an optical fiber communications link
consisting of a photodetector plus amplification and signal-restoring circuitry. Additional components include optical amplifiers, connectors, splices, couplers, regenerators (for restoring the signal-shape characteristics), and other passive components
and active photonic devices.
The cabled fiber is one of the most important elements in an optical fiber link
as is described in Chaps. 2 and 3. In addition to protecting the glass fibers during
installation and service, the cable may contain copper wires for powering optical
amplifiers or signal regenerators, which are needed periodically in long-distance
links for amplifying and reshaping the signal. A variety of fiber types with different
performance characteristics exist for a wide range of applications. To protect the glass
fibers during installation and service, there are many different cable configurations
depending on whether the cable is to be installed inside a building, underground
in ducts or through direct-burial methods, outside on poles, or under water. Very
low-loss optical connectors and splices are needed in all categories of optical fiber
networks for joining cables and for attaching one fiber to another.
Analogous to copper cables, the installation of optical fiber cables can be either
aerial, in ducts, undersea, or buried directly in the ground, as illustrated in Fig. 1.11.
As Chap. 2 describes, the cable structure will vary greatly depending on the specific
application and the environment in which it will be installed. Owing to installation and/or manufacturing limitations, individual cable lengths for in-building or
terrestrial applications will range from several hundred meters to several kilometers.
Practical considerations such as reel size and cable weight determine the actual length
of a single cable section. The shorter segments tend to be used when the cables are
pulled through ducts. Longer lengths are used in aerial, direct-burial, or underwater
applications.
Workers can install optical fiber cables by pulling or blowing them through ducts
(both indoor and outdoor), laying them in a trench outside, plowing them directly
into the ground, suspending them on poles, or laying or plowing them underwater.
Although each method has its own special handling procedures, they all need to
adhere to a common set of precautions. These include avoiding sharp bends of the