Modern electronics are often shielded with metallic packaging to protect them from harmful electromagnetic radiation. In order to determine the effectiveness of the electronic shielding, there is a need to perform non-intrusive measurements of the electric field within the shielding. The requirement to be non-intrusive requires the sensor to be all dielectric and the sensing area needs to be very small. The non-intrusive sensor is attained by coupling a slab of non-linear optical material to the surface of a D shaped optical fiber and is called a slab coupled optical fiber sensor (SCOS). The sensitivity of the SCOS is increased by using an organic electro-optic (EO) polymer.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.