Characterization of embedded fiber Bragg grating sensors written in high-birefringent optical fibers subjected to transverse loading

Experimental, analytical and finite-element-simulation approaches are presented for the characterization of fibre Bragg grating sensors written in conventional monomode and polarization-mantaining fibres subjected to transverse loading. Firstly, a diametrical-load configuration is considered. Numerical simulations show the behaviour to be nonlinear as a function of the applied load when an appropriate analytical model for the opto-mechanical response is employed. Secondly, experiments are carried out with the sensors embedded in epoxy specimens, when the latter are subjected to transversal biaxial loading. The response is monitored as a function of the vertical/horizontal load ratio. A finite-element model of the specimen with the embedded fibre and the previous analytical procedure are used to calculate the strain distributions in the fibre core resulting from loading, and predict the corresponding Bragg wavelength shifts. Experimental results are then compared to numerical predictions.