A LiNbO₃ Optical Sensor for Measurement of the 2-D Intensive Electric Field Vectors

Based on the Pockels effect of LiNbO3 (LN) crystals, a 2-D intensive electric field sensor has been designed, fabricated, and experimentally verified. By using only a single LN crystal, the two orthogonal electric field components can be simultaneously measured, which results in the sensor structure being greatly simplified. Experimental results show that under the power frequency intensive electric field, the linear measurable electric field ranges of the sensor x-axis and y-axis are <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.82-387$ </tex-math></inline-formula> kV/m and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$13.87-383$ </tex-math></inline-formula> kV/m, respectively. When the electric fields are 33.2, 46.2, 83.1, and 116.9 kV/m, by rotating in the xoy plane for 360°, the maximum relative errors of the measured synthesized electric field are 4.51%, 4.32%, 4.08%, and 2.40%, respectively. When the electric field is 33.21 V/m and the resolution bandwidth (RBW) of the spectrum analyzer is 10 Hz, the frequency response fluctuations of the sensor x-axis and y-axis are within ±2 dB from 10 to 600 MHz. Besides, the minimum measurable electric fields are 3.90 and 11.85 V/m, respectively, which results in the linear dynamic ranges are about 99.6 and 89.9 dB, respectively. The developed sensor can be used to measure two orthogonal electric field vectors of a 2-D intensive electric field.