A temperature-insensitive electric field sensor utilizing HF-etched tilted gratings in
a high refractive index solution (E7 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.