Abstract:
wavelength-division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fiber by using different wavelengths (colours) of laser light to carry different signals. This allows for a multiplication in capacity, in addition to enabling bidirectional communications over one strand of fiber. This is a form of frequency division multiplexing (FDM) but is commonly called wavelength division multiplexing.in wavelength division multiplexing a technique to upgrade the transmission bandwidth capacities of existing systems.The major implementations of wavelength multiplexer/demultiplexer devices are discussed in this seminar and especially optical efficiency, spectral stability, crosstalk performance and the number of channels that may be provided

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for more read
http://en.wikipediawiki/Wavelength-divis...ltiplexing
http://networks.cs.ucdavis.edu/~mukherje...node4.html
http://openlearn.open.ac.uk/mod/resource...?id=203416