Influence of Angular Orientation of the Embedded Highly Birefringent Fiber on PMD Changes under Axial Stress

Abstract

In the paper we present results of the research on polarization mode dispersion changes inside the polarimetric optical fiber sensors based on highly birefringent optical fibers embedded into composite materials with different angular orientations of the optical axes. Based on measurements made for different types of highly birefringent optical fiber sensors we have shown that strain sensitivities after lamination process are different in comparison to the data obtained before lamination. Our results indicate that polarization mode dispersion in side-hole highly birefringent fibers under axial stress strongly depends on fiber orientation in the composite material suggesting that orientation of the polarization axes of the highly birefringent fiber can be responsible for behavior of the fiber inside the composite material.

Influence of lamination process on optical fiber sensors embedded in composite material

“…8a), unlike vertical axial orientation, where relative PMD values were decreasing with induced axial stress (Fig. 8b) [17]. The change of the PMD is a consequence of the changes in the birefringence.…”

Numerical Analysis of Stress Distribution in Embedded Polymer and Silica-Glass Highly Birefringent Fibers

“…Depending on the orientation of the fiber relative to the generated stress, changes in birefringence due to the polymerization shrinkage can be either positive or negative [5,6]. It is not easy to measure birefringence changes of the HB fiber that occur during the lamination process.…”

“…To analyze the outgoing polarization at the fiber output, a second polarizer (analyzer) should be also oriented at 45 degrees with respect to both birefringence axes of the fiber. The value of PMD can be calculated by using the following formula: (5) where: c is the speed of light,  1 and  2 respectively represent the lower and upper bounds of the wavelength range and N is the number of light oscillations for a chosen wavelength range.…”