Wavelength-division Wavelength-division multiplexingmultiplexing

Explanation of the technology Explanation of the technology and their applicationand their application How the technology worksHow the technology works Variations of the technologyVariations of the technology Differences between WDM and Differences between WDM and other technologiesother technologies

Explanation of the Explanation of the Technology of the selected Technology of the selected

topictopic

Definition: …Definition: …sending signals of several different sending signals of several different wavelengths…wavelengths…

Advantages of WDMAdvantages of WDM - Capacity- Capacity

- Cost - Cost

- To avoid cross-talk- To avoid cross-talk

Wavelength Division Multiplexer is Wavelength Division Multiplexer is a device…a device…

WDM In TelecommunicationsWDM In Telecommunications - - Adds flexibility Increase the Adds flexibility Increase the

utilizationutilization

How the Technology WorksHow the Technology Works

The highway principle and the ~25 The highway principle and the ~25 THz optical fiber .THz optical fiber .

transmitting several different independent wavelengths transmitting several different independent wavelengths

simultaneouslysimultaneously..

Basic ConceptBasic Concept

1.1. laser must emit light at a different laser must emit light at a different wavelength.wavelength.

2.2. all the lasers' light multiplexed all the lasers' light multiplexed together onto a single optical fiber. together onto a single optical fiber.

Basic ConceptBasic Concept

33. . Transmitted through a high-Transmitted through a high-bandwidth optical fiber .bandwidth optical fiber .

Basic ConceptBasic Concept

44. . Signals must be demultiplexed at Signals must be demultiplexed at the receiving end( the receiving end( by distributing the total optical by distributing the total optical power to each output port and then requiring that each receiver power to each output port and then requiring that each receiver selectively recover only one wavelength by using a tunable selectively recover only one wavelength by using a tunable

optical filteroptical filter) )

CWDMCWDM

Definition: no use of EDFA if some Definition: no use of EDFA if some channel spacing and frequency channel spacing and frequency stability.stability.

procedure: two or more signals , procedure: two or more signals , different wavelengths.different wavelengths.

development: two transceivers , development: two transceivers , (GBIC) ((GBIC) (gigabit interface gigabit interface converterconverter) and (SFP) () and (SFP) (small form-small form-factor pluggablefactor pluggable) , easy ) , easy conversion for transporting.conversion for transporting.

DWDMDWDM

Definition: use of EDFA in different Definition: use of EDFA in different ways and capabilities.ways and capabilities.

Capable of EDFA: amplify any Capable of EDFA: amplify any optical signal.optical signal.

Need more stable wavelength or Need more stable wavelength or frequency.frequency.

Closer spacing wavelength.Closer spacing wavelength.

How the technology of Wavelength-How the technology of Wavelength-division multiplexing differs from division multiplexing differs from

other similar Technologiesother similar Technologies

WDM Vs TDMWDM Vs TDM WDM Vs FDMWDM Vs FDM WDM Vs SCMWDM Vs SCM WDM Vs CDMWDM Vs CDM WDM Vs SDMWDM Vs SDM

WDM Vs TDMWDM Vs TDM

TDM :electrical networks TDM :electrical networks & & optical network at < optical network at < 100-Gbps(Lower-speed )100-Gbps(Lower-speed )

WDM Vs FDMWDM Vs FDM

WDMWDM: applies to an optical carrier. : applies to an optical carrier. FDMFDM :applies to a radio carrier. :applies to a radio carrier.

Medium:Medium: WDMWDM: digital medium.: digital medium. FDMFDM: analog medium : analog medium

WDM Vs SCMWDM Vs SCM

WDMWDM : : modulating a ~terahertz optical carrier wave modulating a ~terahertz optical carrier wave with ~100s Mbps base band data .(The multiplexing and with ~100s Mbps base band data .(The multiplexing and demultiplexing: done optically )demultiplexing: done optically )

sub carrier multiplexing (SCM)sub carrier multiplexing (SCM) : : the the base band data are impressed on a ~gigahertz sub carrier base band data are impressed on a ~gigahertz sub carrier wave that is subsequently impressed on the THz optical wave that is subsequently impressed on the THz optical carrier. .(The multiplexing and demultiplexing: done carrier. .(The multiplexing and demultiplexing: done electronically )electronically )

WDM Vs CDMWDM Vs CDM

Code-division multiplexingCode-division multiplexing ( (CDM) : CDM) : each channel transmits its bits as a coded each channel transmits its bits as a coded

channel-specific sequence of pulses.channel-specific sequence of pulses.

WDM Vs SDMWDM Vs SDM

Space-division multiplexingSpace-division multiplexing ((SDM)SDM) : :each channel occupies its own spatial each channel occupies its own spatial coordinate, and all other channels cannot be transmitted coordinate, and all other channels cannot be transmitted

simultaneously on the same fibersimultaneously on the same fiber

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