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Wavelength division multiplexing


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  • Light and its nature have caused a lot of ink to flow during these last decades. Its dual behavior is partly explained by (1)Double-slit experiment of Thomas Young - who represents the photon’s motion as a wave - and also by (2)the Photoelectric effect in which the photon is considered as a particle. A Revolution: SALEH THEORY solves this ambiguity and this difficulty presenting a three-dimensional trajectory for the photon's motion and a new formula to calculate its energy. More information on
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Wavelength division multiplexing

  1. 1. Is the set of technique that allow thesimultaneous transmission of multiple signals across a single data link.
  2. 2. Multiplexing Analog Digital TDMFDM WDM diagram
  3. 3.  a multiplexing technique working in the wavelength domain An analog multiplexing technique to combine optical signal.
  4. 4.  The concept was first published in 1970, and by 1978 WDM systems were being realized in the laboratory. The first WDM systems only combined two signals. Modern systems can handle up to 160 signals and can thus expand a basic 10 Gbit/s fiber system to a theoretical total capacity of over 1.6 Tbit/s over a single fiber pair.
  5. 5.  In fiber-optic communications Wavelength –division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fiber by using different (colours) of laser light to carry different signals.
  6. 6. With the exponential growth in communications, caused mainly by the wide acceptance of the Internet, many carriers are finding that their estimates of fiber needs have been highly underestimated. Although most cables includedmany spare fibers when installed, this growth has used many of them and new capacity is needed.
  7. 7. 1)installing more cables,2) increasing system bit rate to multiplex more signals3) wavelength division multiplexing.
  8. 8. 1)CWDM2)DWDM
  9. 9.  DWDM No official or standard definition Implies more channels more closely spaced that WDM DWDM-based networks create a lower cost way to quickly respond to customers bandwidth demands and protocol changes. A key advantage to DWDM is that its protocol- and bit-rate independent.
  10. 10.  CWDM No official or standard definition number of channals is fewer than in dense wavelength division multiplexing (DWDM) but more than in standard wavelength division multiplexing (WDM). Laser emmission
  11. 11.  CWDM system have channel at wavelengths spaced 20 nanometers (nm). DWDM 0.4 nm spacing Energy tolerance
  12. 12. • WDM technology allows multiple connections over one fiber thus reducing fiber plant requirement. – This is mainly beneficial for long-haul applications. – Campus applications require a cost benefit analysis.• WDM technology can also provide fiber redundancy.• WDM provides a managed fiber service.