High-sensitivity fiber Bragg grating transverse force sensor based on centroid measurement of polarization-dependent loss

The transverse force measurement by virtue of 'stress-induced birefringence effects' of a fiber Bragg grating (FBG) written in a standard telecom single-mode fiber is attractive in the field of internal strain sensing in materials and structures. However, the measurement suffers from the drawback of low transverse force sensitivity of the FBG. In this paper, we propose utilizing the centroid information of the polarization-dependent loss (PDL) evolution of FBG for transverse force measurements. The evolution of the PDL with wavelength for the transmitted signals with respect to transverse force was analyzed and numerically simulated. Experiments were carried out to verify the reasonability and feasibility of the measurement method. Good agreement between experimental results and numerical simulations has been obtained.