High sensitivity Sagnac interferometric strain sensor based polarization maintaining fibre enhanced coupling

A high sensitivity, simple fabrication all-fibre strain sensor is proposed and demonstrated experimentally. The sensor consists of a section of Panda-type polarization maintaining fibre (PMF) built into a Sagnac interferometer. The Panda-type PMF is intentionally spliced to the single-mode fibre through enhanced fusion splicing to excite high-order polarized modes. The enhanced fusion splicing characterizes a large magnitude of overlap. The measured strain sensitivity reaches up to 32 pm/mu epsilon and the strain resolution of 0.63 mu epsilon has been achieved. The proposed fibre strain sensor characterizing easy fabrication and high sensitivity can be a good candidate in the field of structural health monitoring.