Simultaneous measurement of micro-displacement and temperature based on balloon-like single-mode fiber cascaded with Sagnac interferometer

Abstract

A dual-parameter sensor based on balloon-like single-mode fiber (SMF) cascaded with Sagnac interferometer (SI) to measure displacement and temperature simultaneously is proposed, and the experimentally proved. The balloon-like structure made by bending SMF is sensitive to micro-displacement and temperature. The SI is inserted into a polarization maintaining fiber (PMF). The SI can be utilized not only for temperature measurement but also as temperature compensation for micro-displacement measurement by balloon-like SMF. By optimizing the length of the PMF, the resonant dips of the two structures are independent of each other. Experimental results indicate that the displacement and temperature sensitivities of the composite sensor reach to –326 pm/um and –1.317 nm/℃, respectively. Additionally, this fiber sensor has the advantages of simple structure, high sensitivity, and good stability, which exhibits applications in fields that require precise temperature control.