Performance analysis of all-fiber polarimetric strain sensor for composites structural health monitoring

An improved design comprising a multifiber configuration for a polarimetric fiber optic sensor in real time structural health monitoring is presented in this paper. The sensor is in the form of a multifiber assembly composed of a high-birefringent (HiBi) sensing fiber and a single mode polarization maintaining (PM) fiber or a HiBi fiber as a lead-in and lead-out fiber, all spliced in sequence. The polarization behavior of the assembly is analyzed theoretically using Stokes matrix method for the monochromatic case. Based on this model a phase shift compensation method for multifiber sensors is proposed. The design also helps reduce the bulky optical component in the sensor. The static and dynamic responses of these multifiber sensors are experimentally evaluated to test the structural integrity of composites.