Chapter 10
Wavelength Division Multiplexing
(WDM)
Abstract Wavelength division multiplexing or WDM allows the combining of
a number of independent information-carrying wavelengths onto the same fiber,
because of the wide spectral region in which optical signals can be transmitted
efficiently. This chapter addresses the operating principles of WDM, describes a
wide array of optical sources and passive components needed to implement WDM
links, examines the functions of a generic WDM link, and discusses the internationally standardized spectral grids that designate independent channels for wavelength
multiplexing schemes.
A distinctive operational feature of an optical fiber is that it has a wide spectral region
in which optical signals can be transmitted efficiently. For full-spectrum fibers used
over long distances this region includes an over 400-nm spectrum in the O-band
through the L-band, whereas the 260-nm spectrum in the T-band can be employed
for shorter links such as in data centers. The light sources used in high-capacity
optical fiber communication systems emit in a narrow wavelength band of less than
1 nm, so many different independent optical channels can be used simultaneously in
different segments of a desired wavelength range. The technology of combining a
number of such independent information-carrying wavelengths onto the same fiber
is known as wavelength division multiplexing or WDM [1–6].
Section 10.1 addresses the operating principles of WDM, examines the functions of a generic WDM link, and discusses the internationally standardized spectral
grids that designate independent channels for wavelength multiplexing schemes.
Sections 10.2 through 10.6 describe various categories of passive optical components that are needed to insert separate wavelengths into a fiber at the transmitting
end and separate them into individual channels at the destination. An important factor
in deploying these components in a WDM system is to avoid inter-channel interference by ensuring that optical signal power from one channel does not drift into the
spectral territory occupied by adjacent channels.
Applications of WDM techniques are found in all levels of communication
links including long-distance terrestrial and undersea transmission systems, metro
networks, data center links, and fiber-to-the-premises (FTTP) networks. Chapter 13
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
G. Keiser, Fiber Optic Communications,
https://doi.org/10.1007/978-981-33-4665-9_10
383
Wavelength Division Multiplexing
(WDM)
Abstract Wavelength division multiplexing or WDM allows the combining of
a number of independent information-carrying wavelengths onto the same fiber,
because of the wide spectral region in which optical signals can be transmitted
efficiently. This chapter addresses the operating principles of WDM, describes a
wide array of optical sources and passive components needed to implement WDM
links, examines the functions of a generic WDM link, and discusses the internationally standardized spectral grids that designate independent channels for wavelength
multiplexing schemes.
A distinctive operational feature of an optical fiber is that it has a wide spectral region
in which optical signals can be transmitted efficiently. For full-spectrum fibers used
over long distances this region includes an over 400-nm spectrum in the O-band
through the L-band, whereas the 260-nm spectrum in the T-band can be employed
for shorter links such as in data centers. The light sources used in high-capacity
optical fiber communication systems emit in a narrow wavelength band of less than
1 nm, so many different independent optical channels can be used simultaneously in
different segments of a desired wavelength range. The technology of combining a
number of such independent information-carrying wavelengths onto the same fiber
is known as wavelength division multiplexing or WDM [1–6].
Section 10.1 addresses the operating principles of WDM, examines the functions of a generic WDM link, and discusses the internationally standardized spectral
grids that designate independent channels for wavelength multiplexing schemes.
Sections 10.2 through 10.6 describe various categories of passive optical components that are needed to insert separate wavelengths into a fiber at the transmitting
end and separate them into individual channels at the destination. An important factor
in deploying these components in a WDM system is to avoid inter-channel interference by ensuring that optical signal power from one channel does not drift into the
spectral territory occupied by adjacent channels.
Applications of WDM techniques are found in all levels of communication
links including long-distance terrestrial and undersea transmission systems, metro
networks, data center links, and fiber-to-the-premises (FTTP) networks. Chapter 13
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
G. Keiser, Fiber Optic Communications,
https://doi.org/10.1007/978-981-33-4665-9_10
383