Study of Small Radial Stresses Sensing Using Polarization Properties of Fiber Bragg Grating

Different form the basic sensing theory of the fiber Bragg grating (FBG) sensors based on spectral analysis, a new method exploiting the polarization properties of FBG for radial stresses sensing is proposed. In this paper, the birefringence effects on FBG under radial stresses are analyzed and a numerical simulation based on the piecewise-uniform approach is also used to simulate the spectral responses of FBG under some typical radial stresses fields. The evolution of the polarization dependent loss (PDL) of FBG with wavelength for the transmitted signals with respect to the radial stresses is also studied theoretically and experimentally. The theoretical analysis suggests that the PDL of FBG is more suitable for measuring radial stresses than single spectral analysis because of its greater sensitivity. Good agreements between experimental results and numerical simulations have been obtained.