Wavelength-division multiplexing

DWDMwavelength division multiplexingWDMdense wavelength division multiplexingdense wavelength-division multiplexingCWDMwavelength division multiplexedwave division multiplexingcoarse wavelength division multiplexingDense Wavelength Division Multiplexing (DWDM)
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.wikipedia
226 Related Articles

Fiber-optic communication

fiber-opticfiber optic communicationsfiber-optic network
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.
The fourth generation of fiber-optic communication systems used optical amplification to reduce the need for repeaters and wavelength-division multiplexing to increase data capacity.

Multiplexing

multiplexedmultiplexmultiplexes
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.
A variant technology, called wavelength-division multiplexing (WDM) is used in optical communications.

Optical fiber

fiber opticfiber opticsfiber-optic
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.
Each fiber can carry many independent channels, each using a different wavelength of light (wavelength-division multiplexing (WDM)).

Optical add-drop multiplexer

OADMoptical (de)multiplexerOptical Add/Drop Multiplexer
With the right type of fiber, it is possible to have a device that does both simultaneously and can function as an optical add-drop multiplexer.
An optical add-drop multiplexer (OADM) is a device used in wavelength-division multiplexing systems for multiplexing and routing different channels of light into or out of a single mode fiber (SMF).

Frequency-division multiplexing

frequency division multiplexingFDMfrequency division multiplex
The term WDM is commonly applied to an optical carrier, which is typically described by its wavelength, whereas frequency-division multiplexing typically applies to a radio carrier which is more often described by frequency.
An analogous technique called wavelength division multiplexing is used in fiber-optic communication, in which multiple channels of data are transmitted over a single optical fiber using different wavelengths (frequencies) of light.

Fabry–Pérot interferometer

Fabry–PérotetalonFabry–Pérot etalon
The optical filtering devices used have conventionally been etalons (stable solid-state single-frequency Fabry–Pérot interferometers in the form of thin-film-coated optical glass).

Optical Transport Network

OTNG.798Optical Transport
An ONE may Re-time, Re-Amplify, Re-shape (3R) but it does not have to be 3R – it can be purely photonic.

G.709

G.709/Y.1331ODUkRecommendation G.709
It is a standardized method for transparent transport of services over optical wavelengths in DWDM systems.

Optical amplifier

optical amplifiersEDFAoptical amplification
By using WDM and optical amplifiers, they can accommodate several generations of technology development in their optical infrastructure without having to overhaul the backbone network.
The broad gain-bandwidth of fiber amplifiers make them particularly useful in wavelength-division multiplexed communications systems as a single amplifier can be utilized to amplify all signals being carried on a fiber and whose wavelengths fall within the gain window.

Multiplexer

demultiplexermultiplexersMUX
A WDM system uses a multiplexer at the transmitter to join the several signals together and a demultiplexer at the receiver to split them apart.

Single-mode optical fiber

single-mode fibersingle-modeSMF
Most WDM systems operate on single-mode fiber optical cables which have a core diameter of 9 µm.
By using optical amplifiers and dispersion-compensating devices, state-of-the-art DWDM optical systems can span thousands of kilometers at 10 Gbit/s, and several hundred kilometers at 40 Gbit/s.

Arrayed waveguide grating

Arrayed waveguide gratings (AWG) are commonly used as optical (de)multiplexers in wavelength division multiplexed (WDM) systems.

Multi-mode optical fiber

multi-mode fibermulti-modemultimode
Certain forms of WDM can also be used in multi-mode fiber cables (also known as premises cables) which have core diameters of 50 or 62.5 µm.
Some 200 and 400 Gigabit Ethernet speeds use wavelength-division multiplexing (WDM) even for multi-mode fiber which isn't specified up to and including OM4.

IPoDWDM

IP over DWDM (IPoDWDM) is a technology used in telecommunications networks to integrate IP Routers and Switches in the OTN (Optical Transport Network).

Synchronous optical networking

SONETSDHSynchronous Digital Hierarchy
EDFAs were originally developed to replace SONET/SDH optical-electrical-optical (OEO) regenerators, which they have made practically obsolete. The introduction of the ITU-T G.694.1 frequency grid in 2002 has made it easier to integrate WDM with older but more standard SONET/SDH systems.
Where fiber exhaustion is a concern, multiple SONET signals can be transported over multiple wavelengths on a single fiber pair by means of wavelength-division multiplexing, including dense wavelength-division multiplexing (DWDM) and coarse wavelength-division multiplexing (CWDM).

10 Gigabit Ethernet

10GBASE-T10GbE10 GbE
The 10GBASE-LX4 10 Gbit/s physical layer standard is an example of a CWDM system in which four wavelengths near 1310 nm, each carrying a 3.125 gigabit-per-second (Gbit/s) data stream, are used to carry 10 Gbit/s of aggregate data. Cisco's Enhanced WDM system combines 1 Gb Coarse Wave Division Multiplexing (CWDM) connections using SFPs and GBICs with 10 Gb Dense Wave Division Multiplexing (DWDM) connections using XENPAK, X2 or XFP DWDM modules.
It uses four separate laser sources operating at 3.125 Gbit/s and coarse WDM with four unique wavelengths around 1310 nm.

Frequency grid

ITU standardized
The introduction of the ITU-T G.694.1 frequency grid in 2002 has made it easier to integrate WDM with older but more standard SONET/SDH systems.
The most common frequency grid used for fiber-optic communication is that used for channel spacing in Dense Wavelength Division Multiplexing (DWDM) at wavelengths around 1550 nm and defined by ITU-T G.694.1.

Dark fibre

dark fiberdark fiber networkdark fibre network
The availability of wavelength-division multiplexing reduced the demand for fibre by increasing the capacity that could be placed on a single fibre by a factor of as much as 100.

Super-channel

A super-channel is an evolution in Dense Wavelength Division Multiplexing (DWDM) in which multiple, coherent optical carriers are combined to create a unified channel of a higher data rate, and which is brought into service in a single operational cycle.

XFP transceiver

XFPXFIXFP ports
Cisco's Enhanced WDM system combines 1 Gb Coarse Wave Division Multiplexing (CWDM) connections using SFPs and GBICs with 10 Gb Dense Wave Division Multiplexing (DWDM) connections using XENPAK, X2 or XFP DWDM modules.
They can operate over a single wavelength or use dense wavelength-division multiplexing techniques.

Transponder

transpondersCground beacon
See also transponders (optical communications) for different functional views on the meaning of optical transponders.

Optical mesh network

Optical Mesh Networksmesh networksmesh optical networks
Technological advancements in optical transport switches in the first decade of the 21st century, along with continuous deployment of dense wavelength-division multiplexing (DWDM) systems, have led telecommunications service providers to replace their SONET ring architectures by mesh-based architectures for new traffic.

Add-drop multiplexer

Add Drop Multiplexersadd/drop branching unitsADM
ADMs can be used both in long-haul core networks and in shorter-distance "metro" networks, although the former are much more expensive due to the difficulty of scaling the technology to the high data rates and dense wavelength division multiplexing (DWDM) used for long-haul communications.

ITU-T

CCITTITU Telecommunication Standardization SectorTelecommunication Standardization Sector

Small form-factor pluggable transceiver

SFPQSFPSFP+
Some GBIC and small form factor pluggable (SFP) transceivers utilize standardized CWDM wavelengths.