Experimental Demonstration to Enhance the Curvature Sensitivity of a Fiber Mach-Zehnder Interferometer Based on a Waist-Enlarged Technique Using Polymer

A fiber curvature sensor based on a Mach-Zehnder Interferometer (MZI) constructed using the waist-enlarged technique to splice a segment of non-zero dispersion-shifted fiber (NZ-DSF) between two segments of single mode fiber (SMF) is proposed and experimentally demonstrated. All fabricated sensors presented an improvement in their curvature sensitivity when they were coated with polydimethylsiloxane (PDMS) polymer. The sensor that exhibited the best performance was 6.5 cm long, with a curvature sensitivity of 8.27 nm/m-1 in a range of 0.69 m-1 (from 1.08 to 1.77 m-1). This sensitivity is 3.22 times higher than that of the sensor without polymer. Additionally, the sensor coated with polymer exhibited cross-sensitivity that is 2.23 times smaller than the sensor without polymer. The easy fabrication and notable performance of this device makes it alluring for structural health monitoring.