Wave multiplexer and demultiplexer

Basic passive elements of systems with multiplexing of the wavelenght are multiplexer and demultiplexer of the wave lenght. They allow to combine many signals with different wavelenghts, incoming via separate inputs into one signal (multiplexer) or to divide the input signal with many wavelenghts between many outputs in such way, that to each output comes only one signal with specific wavelenght (demultiplexer).