Module 19 : WDM Components
Lecture     : WDM Components - I
 
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The filter $ F_1$is a short wavelength pass filter while $ F_2$is a long wavelength pass filter. Light from the input port becomes parallel at the end of the lens. The shorter wavelength is reflected by $ F_2$and enters through $ F_1$to the lower ouput fiber. The longer wavelength enters through $ F_2$and is reflected by the plane mirror. It is focussed on to the second output port through the filter $ F_1$. The same principle can be used to design a multiplexer.

A sequence of interference filters, each of which is designed to transmit a single wavelength can be used to design a DEMUX, as shown in the figure. To demultiplex $ n$wavelengths, we would need $ n-1$such filters. The transmitted signal at each port is collected by a lens and fed to the output fiber of the DEMUX.

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