LiNbO₃ Crystal Intense Electric Field Sensor Coupled With Twisted Polarization Maintaining Fiber
Jiahong Zhang, Xinyu Wang, Yuanying Zhang
Abstract
A lithium niobite (LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , LN) optical intense electric field sensor with linear operating point set by twisting the polarization-maintaining fiber (PMF) was designed, developed and experimentally demonstrated. Experimental results reveal that the coupling efficiency of the sensor is improved by 25.3% compared with traditional optical electric field sensor using the 1/4 wave plate. Besides, for measurement of intense power frequency electric field, the linear measurement range of the sensor is 12.8 ~ 524 kV /m, and the linear correlation coefficient is 0. 9989. For measurement of lightning electromagnetic pulse (LEMP), it was found that the sensor detected waveform was superimposed with resonant noise of 720 kHz and 980 kHz. Theoretical analysis yielded a relationship between the direction of the applied electric field, crystal size and resonant frequency. The resonance energy was eventually dispersed by using a trapezoidal LN crystal, and it was found the resonant noise has been suppressed to below -30 dB.