Finite element analysis of a novel weak-pressure sensor based on fiber Bragg gratings in photonic crystal fibers

The fiber Bragg grating has been widely used in sensors. We have studied the spectral properties of uniform Bragg gratings in photonic crystal fibers under transverse pressure. By the finite element method, the relation between the birefringence and the pressure was simulated in bare photonic crystal fibers. The results show that the birefringence is changed even under weak pressure. A new method based on polarization-dependent loss is presented for measuring pressure. The maximal amplitude of the polarization-dependent loss varies linearly in the pressure range of 0 to 4 MPa with a slope of 0.75 MPa−1.