WDM systems I

Module 19 : WDM Components

Lecture : WDM Components - I

	$\includegraphics[width=\textwidth]{wdm1}$
	A wavelength multiplexer (MUX) combines incident wavelengths and launches the output to the fiber. At the receiving end a demultiplexer (DEMUX) reverses the above and separates the signal into the components. Multiplexers are generally based on one of two principles, viz., angular dispersion and optical filtering. Prism and reflection gratings are used for separating wavelengths. The same elements can combine wavelengths on reversing the direction of the beams.
	$\includegraphics[width=\textwidth]{wdm2}$ Reflection gratings can also be used to separate wavelengths. By choosing a suitable periodic structure for the grating, it is possible to coincide the directions of constructive interference and specular reflection from the grating for a given order and wavelength. The technique is known as blazing .