Finite element analysis of piezoelectric polymer-coated D-fiber intended for electric field sensing

We report, for the first time, the advantage of using a polymer-coated D-fiber over conventional circular fiber as the sensing element in an all-fiber electric field sensor. Finite element analysis has been used to study the strains in a D-fiber subjected to an external electric field. The optical D-fiber carrying a transversely poled piezoelectric poly(vinylidene fluoride) polymer coating was modeled by using three-dimensional stress analysis. The response of the D-fiber electric field sensor was determined over a wide frequency range from 100 Hz to 50 MHz. The modeling predicts that the resulting strains will cause a phase shift of 0.06 rad / V/ m in the low-frequency (axially unconstrained) region and 0.002 Pad / V/ m in the high-frequency (axially constrained) region. An increase in the phase modulation sensitivity by a factor of 3 compared to conventional circular fiber has been achieved by utilizing the unique properties of the D-fiber structure.