With the exponential growth in communications, caused largely by the
wide acceptance of the Internet, many carriers have found their
estimates of fiber needs have been highly underestimated. Although most
cables included many spare fibers when installed, this growth has used
many of them and new capacity is required. Make use of a number of ways
to improve this problem, eventually the WDM has shown more cost
effective in most cases.
WDM Definition:
Wave
Division Multiplexing (WDM) enables multiple data streams of varying
wavelengths ("colors") to become combined right into a single fiber,
significantly enhancing the overall capacity from the fiber. WDM can be
used in applications where considerable amounts of traffic are needed
over long distance in carrier networks. There's two types of WDM
architectures: Course Wave Division Multiplexing (CWDM) and Dense Wave
Division Multiplexing (DWDM).
WDM System Development History:
A
WDM system uses a multiplexer in the transmitter to become listed on
the signals together, and a demultiplexer at the receiver to separate
them apart. With the right type of fiber it is possible to have a device
that does both simultaneously, and can work as an optical add-drop
multiplexer. The optical filtering devices used have conventionally been
etalons (stable solid-state single-frequency Fabry¡§CP¡§|rot
interferometers by means of thin-film-coated optical glass).
The
idea was first published in 1980, and by 1978 WDM systems appeared to be
realized in the laboratory. The first WDM systems combined 3 signals.
Modern systems are designed for as much as 160 signals and can thus
expand a fundamental 10 Gbit/s system over a single fiber pair to in
excess of 1.6 Tbit/s.
WDM systems are well-liked by
telecommunications companies because they allow them to expand the
capacity of the network without laying more fiber. By utilizing WDM and
optical amplifiers, they can accommodate several generations of
technology rise in their optical infrastructure without needing to
overhaul the backbone network. Capacity of a given link can be expanded
by simply upgrades towards the multiplexers and demultiplexers at each
end.
This is often made by use of optical-to-electrical-to-optical
(O/E/O) translation in the very edge of the transport network, thus
permitting interoperation with existing equipment with optical
interfaces.
WDM System Technology:
Most WDM
systems operate on single-mode fiber optical cables, which have a core
diameter of 9 µm. Certain forms of WDM may also be used in multi-mode
fiber cables (also referred to as premises cables) which have core
diameters of fifty or 62.5 µm.
Early WDM systems were expensive
and complicated to operate. However, recent standardization and better
understanding of the dynamics of WDM systems make WDM less expensive to
deploy.
Optical receivers, as opposed to laser sources, tend to be
wideband devices. Therefore the demultiplexer must provide the
wavelength selectivity of the receiver in the WDM system.
WDM
systems are split into different wavelength patterns,
conventional/coarse (CWDM) and dense (DWDM). Conventional WDM systems
provide up to 8 channels within the 3rd transmission window (C-Band) of
silica fibers around 1550 nm. Dense wavelength division multiplexing
(DWDM) uses the same transmission window but with denser channel
spacing. Channel plans vary, but a typical system would use 40 channels
at 100 GHz spacing or 80 channels with 50 GHz spacing. Some technologies
are capable of 12.5 GHz spacing (sometimes called ultra dense WDM).
Such spacings are today only achieved by free-space optics technology.
New amplification options (Raman amplification) enable the extension of
the usable wavelengths towards the L-band, pretty much doubling these
numbers.
Coarse wavelength division multiplexing (CWDM) in
contrast to conventional WDM and DWDM uses increased channel spacing to
allow less sophisticated and thus cheaper transceiver designs. To supply
8 channels on one fiber CWDM uses the whole frequency band between
second and third transmission window (1310/1550 nm respectively)
including both windows (minimum dispersion window and minimum
attenuation window) but the critical area where OH scattering may occur,
recommending using OH-free silica fibers in case the wavelengths
between second and third transmission window ought to be used. Avoiding
this region, the channels 47, 49, 51, 53, 55, 57, 59, 61 remain and
these are the most commonly used.Each WDM Optical MUX includes its
optical insertion loss and isolation measures of every branch. WDMs are
available in several fiber sizes and kinds (250µm fiber, loose tube,
900µm buffer, Ø 3mm cable,simplex fiber optic cable or duplex fiber cable).
WDM,
DWDM and CWDM are based on the same idea of using multiple wavelengths
of sunshine on one fiber, but differ within the spacing of the
wavelengths, quantity of channels, and also the capability to amplify
the multiplexed signals within the optical space. EDFA provide an
efficient wideband amplification for that C-band, Raman amplification
adds a mechanism for amplification in the L-band. For CWDM wideband
optical amplification is not available, limiting the optical spans to
many tens of kilometres.
Regardless if you are WDM Optical MUX
expert or it is your first experience with optical networking
technologies, FiberStore products and services are equipped for
simplicity of use and operation across all applications. If you want to
choose some fiber optic cable to connect the WDM, you are able to make
reference to our fiber optic cable specifications.Have any questions,
pls contact us.
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