Validation of a single-mode polymer optical fiber sensor and interrogator for large strain measurements

A single-mode polymer optical fiber (POF) in a Mach-Zehnder interferometer configuration is validated for the measurement of tensile nominal elongation of the POF up to 10%. The single-mode POF sensors were unmounted and surface mounted on aluminum tensile coupons for strain measurements. The measured strains from the POF sensors were compared to extensometer measurements for validation. The phase response of the interferometer was measured with a 3 x 3 coupler interrogator. The coupler arrangement was configured to permit the extraction of potential intensity changes in the sensor arm. The phase-shift-strain response of the POF sensors was repeatable for the loading and unloading measurements. The nonlinearity of the phase-shift-strain response was greater than that measured during pure tensile loading of the POF, presumably due to the behavior of the adhesive between the optical fiber and the aluminum coupons.