Design of a lithium niobate electric field sensor with improved sensitivity

This paper analyzes the effect of the crystal geometry size on measurement sensitivity. It is concluded that the sensitivity of the sensor can be improved by increasing the size of the lithium niobite (LN) crystal along the direction of the applied electric field while reducing the size along the vertical direction of the applied electric field. Four sensors with LN crystal sizes of 3 x 3 x 42.2 mm3, 3 x 6 x 42.2 mm3, 6 x 6 x 42.2 mm3 and 3 x 18 x 42.2 mm3 are designed and fabricated. The experiment results indicate that the sensitivity increases by a factor of 3.7 with the crystal thickness and length unchanging while the crystal width is increased from 3 mm to 18 mm. The sensor sensitivity increases by a factor of 5 with the crystal width and length unchanging while the crystal thickness is reduced from 6 mm to 3 mm. Further analysis shows that by designing the sensor using a trapezoidal crystal, the resonant of the sensor can be suppressed. Experimental results show that the piezoelectric resonance of the sensor using trapezoidal LN is suppressed by 60 % compared with that using cuboid LN.