Influence of the lamination process on the strain sensitivity of the fiber sensors embedded in composite materials

Fiber-optic sensors based on highly birefringent (HB) polarization- maintaining (PM) fibers represent a promising generation of sensing devices also known as polarimetric fiber sensors. They utilize polarization (phase) modulation within fibers to sense external perturbations [1]. HB polarimetric sensors can be made temperature insensitive but to measure strain they require means for setting a zero strain reference. Composite structures are made from two or more constituent materials with significantly different physical or chemical properties and they remain separate and distinct in a macroscopic level within the finished structure. This feature allows for the introduction of an optical fiber sensors matrix into the composite material. In this paper we present experimental evidence that the interactions between the composite material and optical fibers during manufacturing process are very significant. The lamination process can dramatically change the strain sensitivity of the highly birefringent (HB) fibers.