Improvements in electric field sensor sensitivity by exploiting a tangential field configuration

This paper presents improvements to slab-coupled optical fiber sensors (SCOS) for electric-field sensing. The improvements are based on changing the crystal cut and orientation of the slab waveguide in combination with altering the input light polarization. Traditional SCOS are fabricated using z-cut potassium titanyl phosphate crystals and are operated with TM polarized light. They have been shown to detect fields as low as 100 V/m. By using an x-cut crystal and TE polarized light, the sensitivity to electric fields is increased 8x due to, primarily, an increase in electric field penetration into the slab by exploiting a tangential boundary condition, and secondly, an increase to the effective electro-optic coefficient of the slab.