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Working mechanism of WDM

Short answer

Wavelength Division Multiplexing assigns each signal a distinct laser wavelength. A prism or diffraction grating multiplexer combines them into one optical fiber. At the receiver, a demultiplexer separates the wavelengths to individual detectors, increasing fiber capacity without interference. Dense WDM (DWDM) supports up to160 channels.

Explain the working mechanism of WDM.

Wavelength division multiplexing (WDM) is an analog multiplexing technique for optical fibre in which signals of different wavelengths (colours) of light are combined and sent together in one fibre. It is the same idea as FDM, but applied to light.

Working

  1. Each input is carried by its own laser at a different wavelength λ1, λ2, λ3 ...
  2. A multiplexer (prism or diffraction grating) combines these narrow beams into one beam that goes through a single fibre.
  3. At the receiving end a demultiplexer splits the beam back into separate wavelengths, and each goes to its own detector.
 λ1 -->|      |                 |      |--> λ1
 λ2 -->| MUX  |==== fibre ======| DMUX |--> λ2
 λ3 -->|      |                 |      |--> λ3

Channels do not interfere because their wavelengths differ. Dense WDM (DWDM) carries 40 to 160 channels in one fibre, which multiplies capacity many times.

✓ Answer checked by Claude Sonnet 5.5

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