Wavelength selection switches for optical application

DETAILED DESCRIPTION This invention is based on the observation that, by making use of filters that selectively passes and reflects radiation of different wavelengths, it is possible to reduce the number of components as well as the overall size of the Add-Drop module.
Thus, one embodiment of the invention is directed towards an apparatus for transmitting radiation of multiple wavelengths.
A first input channel carries radiation of one or more wavelengths and a second input channel carries radiation of a first wavelength to be added.
At least one filter is placed between the channels.
When a switch member is placed in a first position between the channels, radiation carried by the first input channel is received by an output channel and the radiation of the first wavelength carried by the second input channel is received by another output channel.
When the switch member is in the second position between these channels, at least some of the radiation carried by the two input channels impinges on at least one filter.
This causes radiation of all but one of the wavelengths carried by the first input channel and the radiation of the first wavelength to be directed towards a first one of the two output channels and radiation of the wavelength carried by the first input channel but not received by the first output channel be directed towards the remaining output channel.