Distributed Few-Mode Fiber Point Sensor

Point sensors, where a short piece of few-mode fiber (FMF) is spliced between single-mode fibers (SMF), work by monitoring the phase shift in the interference between two guided modes of the FMF, induced by e.g. changes in the temperature or the strain applied to the FMF. So far, such sensors have only been demonstrated as single-point sensors. Here, the method of [3], introduced to distinguish the interference between the fundamental mode and two higher-order modes, is applied to separate the interferences generated in FMF sections of different lengths.