WDM systems I

Module 19 : WDM Components

Lecture : WDM Components - I

	$\includegraphics{wdm6}$
	The problem of using so many filters is that at each reflection there is some power loss which adds up to a substantial fraction of signal power. The way to minimize losses is to pass the signal through high and low pass filters which helps in splitting the signal into wavelength groups. If the incoming signal has $n$ wavelengths and we use, say, 4 pass filters of decreasing bandwidth for transmission, it would divide the signal into 5 groups each of which could then be demultiplexed using interference filters. If the groups contain $n/5$ wavelengths each, each wavelength would have been subjected to a maximum $n/5$ reflections (one reflection at the pass-filter and $n/5-1$ at the interference filter). It may be noted that the process does not reduce the number of filters.