Miniaturized fiber coupled RF E-field sensor with high sensitivity

Electric field measurements with high spatial resolution and high sensitivity are desirable in many technical and medical applications, such as EMC or antenna measurements. Furthermore, the possibility to measure single field components on board during the design and development phase of printed circuit boards is another envisaged market for microwave E-field sensors. Obviously, utilizing optical sensor systems for E-field measurements in the RF frequency range offer the advantage of minimizing interference with the measured field together with the potential to obtain frequency selective amplitude and phase information of the measured field. Due to the availability of efficient small-size electrooptic converters it is possible to develop miniaturized sensor heads with large dynamic range and high sensitivity. We present the results of small-size (l0mmx8mmx2mm) optically powered sensor that uses the sensitivity of an electroabsorption modulator linked to a short monopole antenna via a transimpedance amplifier.