Hybrid structure optical fiber sensor for simultaneous measurement of curvature and strain

A hybrid structure sensor is proposed for curvature and strain measurement. The sensor is fabricated by cascading the Michelson interferometer (MI) based on the up-taper and the Fabry-Perot interferometer (FPI) based on the air cavity. The MI is sensitive to curvature, and the FPI is sensitive to strain. Therefore, the cascade of sensing structures can realize the simultaneous measurement of curvature and strain. The curvature and strain sensitivity of the sensing structure are 2.59 nm/m-1 and 1.63 pm/με, respectively. The cascade of the FPI and the MI enables the end face of the MI to be effectively encapsulated, avoiding the crosstalk of external factors. The hybrid structure sensor has the advantages of simple structure, low cost, and easy preparation. The structure has the potential to be applied to structural health detection and biomedicine.