Nowadays, many people rely on optical networking systems for telecommunications, and the demand for a higher-speed network is growing dramatically. Wavelength Division Multiplexing (WDM) techniques deployed in optical transport network may be the suitable methods to meet this demand.

ITU-T defines an Optical Transport Network (OTN) as a set of Optical Network Elements (ONE) connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals. It was designed to create a transparent, hierarchical network by using wavelength-division multiplexing (WDM).

In fiber optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity. WDM is similar to frequency-division multiplexing (FDM) except one aspect that the former is commonly applied to an optical carrier (which is typically described by its wavelength), whereas the latter typically applies to a radio carrier (which is more often described by frequency).

A WDM system uses a multiplexer at the transmitter to join the signals together, and a demultiplexer at the receiver to split them apart. It is divided into different wavelength patterns, CWDM (coarse-wavelength division multiplexing) and DWDM (dense-wavelength division multiplexing). CWDM is a technology mostly applied for cost- effective consideration, while DWDM is utilized to increase bandwidth over existing fiber optic backbones.

Based on DWDM technology, there are a series of DWDM equipment, such as DWDM transceivers, and DWDM multiplexers and demultiplexers. For example, DWDM multiplexer, generally called DWDM MUX, is widely used in WDM fiber optical networks to receive an optical data signal from the client-layer, such as Synchronous optical networking [SONET/SDH] or another type of data signal, and convert this signal into the electrical domain and re-transmits the signal at a specific wavelength using a 1,550 nm band laser. These data signals are then combined together into a multi-wavelength optical signal using an optical multiplexer, for transmission over a single fiber. In contrast, DWDM demultiplexer, generally called DWDM DEMUX, is used to separate the multi-wavelength optical signal back into individual data signals and output them on separate fibers for client-layer systems (such as SONET/SDH). The image below just shows how multiplexer and demultiplexer work.

As for DWDM price, it is a little expensive for some consumers since this kind of technology needs high-precision filters and lasers which operate at a constant temperature. High-precision, high-stability lasers are expensive, giving rise to a high price of DWDM.

The use of WDM in optical transport network can effectively multiply the bandwidth of fiber optic communication systems Fiberstore provides various WDM optical network solutions, such as transceivers, multiplexers, splitters, amplifiers, attenuators, and so on. You can visit Fiberstore for more information about WDM devices.

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