Choosing relative optical path delays in series-topology interferometric sensor arrays

We consider the problem of selecting relative optical path delays for a chain of Mach-Zehnder interferometric sensors which are to be multiplexed using a frequency modulated source (FMCW multiplexing) or a short coherence-length source (coherence multiplexing). Possible sets of delays which do not lead to crosstalk are described for two different series topologies. It is shown that the rapid growth of required delay with sensor number can be ameliorated if some cross-talk is allowed.