Measurement of multipath interference in the coherent cross-talk regime

We compare various techniques to measure MPI in devices exhibiting distributed coherent crosstalk. Such devices are susceptible to deterministic noise as well as intermittent fading, and the measurement technique employed must capture both these manifestations of MPI. We evaluate several measurement techniques used to characterise MPI in few mode fibers. The coherent, distributed nature of MPI in few-mode fibers leads to fast fluctuations, manifesting in deterministic noise, as well as slow variations, reminiscent of fading in mobile communications systems. Slow temporal intensity variations of a CW DFB laser captures most of the relevant information.