Theoretical and Experimental Analysis of the Directional RI Sensing Property of Tilted Fiber Grating

In this article, we have theoretically and experimentally investigated the unique vector refractive index (RI) sensing property of tilted fiber grating (TFG). Due to orthogonal symmetric structure, TFGs would mainly achieve coupling between core mode two polarization LP1m cladding mode. And numerical simulation results showed that coefficient fundamental is higher than others. experiment, furthermore observed field distribution excessively TFG (Ex-TFG) long period (LPFG), which indicated evanescent shows an asymmetric near with lobes oriented along fast axis TFG, one LPFG has a circularly distribution. addition, by employing side-immersion method, measured azimuth RI sensitivities Ex-TFG, Bragg (TFBG) LPFG, exhibited both Ex-TFG TFBG shown direction-dependency sensitivity, sensitivity almost half slow axis, independent. Overall, experiment show inherently directional property, could be potentially applied in area.