Sensitivity enhanced electric field sensing with etched tilted fiber Bragg grating and a liquid crystal

A temperature-insensitive electric field sensor utilizing HF-etched tilted gratings in a high refractive index solution (E 7 liquid crystal) is proposed. The electric field causes a change in the original arrangement of molecules, thereby altering the refractive index of liquid crystals. This study demonstrates that a combination of liquid crystal and HF-etched tilted gratings effectively excites the cladding leakage mode of the tilted grating. Compared to a non-etched tilted fiber Bragg grating, the proposed sensor exhibits higher sensitivity to electric fields. The experimental results show that the electric field sensitivity of a tilted grating with a diameter of 17.7 µm is 0.024 dB/(kV/cm). The influence of external temperature on the electric field sensor of this design is relatively small, only showing a sensitivity of 0.003 dB/°C. This characteristic is very attractive in practical applications such as industry and healthcare.