Liquid Crystal-Embedded Tilted Fiber Grating Electric Field Intensity Sensor

We propose and experimentally demonstrate a novel electric field intensity sensor by using a tilted fiber Bragg grating (TFBG) interacting with liquid crystal. The TFBG is surrounded by the liquid crystal whose effective refractive index changes over the range from 1.53 to 1.70 in response to the strength of external electric fields. The guiding properties of cladding modes excited in the TFBG are, therefore, sensitive to the external electric field. By monitoring the amplitude of a selected cladding mode resonance, we measured electric field strength over a range of 1.0–4.8 kV/cm. The sensor demonstrated better than 99% linearity with a sensitivity of 0.287 dB/kV/cm. Temperature cross-sensitivity can be effectively reduced by referenced to the core mode of the proposed TFBG sensor.