Sensitivity improvement of integrated optical E-field sensor based on common path interferometer

Integrated optical E-field sensors (IOESs) have been widely applied in electromagnetic field measurements. IOES based on common path interferometer (CPI) has remarkable advantages such that it has better temperature stability of the operating point and satisfying controllability of the optical bias. But the sensitivity of the CPI based IOES is so low that it cannot meet the sensitivity requirement, even for intense E-field measurement. In this research, the sensitivity was improved by designing dipole antennas and electrodes around the waveguide. Firstly, the principle of the sensor is analyzed, showing that the sensitivity cannot be notably improved by increasing the device dimension. Secondly, the relationship between the half-wave E-field and the dipole antenna/ electrode parameters is presented, with the conclusion that the length of the antenna and the distance between the electrodes will significantly affect the half-wave E-field. Thirdly, the experimental results are illustrated. The difference between the designed value and the measured result of the half-wave E-field is less than 5 %, and the fabricated sensor has a linear dynamic range from 10 kV/m to 400 kV/m. The sensitivity is improved by about 20 times with the dipole antenna and electrode.