PLATE BEAM-SPLITTERS AND SYMMETRICAL MULTIPORTS

We show that for experimental arrangements with few nonvacuum inputs t he fully symmetric multiport can be replaced by a simpler partially sy mmetric multiport. This device is equivalent to a beam splitter arrang ement where the number of necessary beam splitters increases linearly with increasing number of inputs, that is it is considerably simpler t o realize owning to the smaller number of components needed.