Dynamics for different light sources of the polarimetric fiber sensor used for strain measurement in composite material

Abstract

Polarimetric optical fiber sensors belong to phase sensors in which polarization state of the output light depends on birefringence of the fiber. In general, external stresses can change birefringence of the fibers. Hence polarimetric sensors may be used for strain monitoring inside composite materials. Length of the sensing fiber of the polarimetric sensor is relatively high, particularly when used to measure strain in composite material, thus light traveling through the sensing fiber may become depolarized and dynamics η of the sensor diminishes. In the paper it is shown that by the use of compensation, depolarization of the light passing through the sensor is significantly reduced. This allows use of less expensive and more robust light sources than laser diodes which are important when the sensor is designed to operate in harsh environment. A comparison of different light sources and sensing fibers for application in strain measurement in composite materials is presented and discussed and an influence of the lamination process on sensor dynamics is evaluated.