Ultrasensitive Optical Electric Field Sensor Based on Harmonic Vernier Effect

This article proposed and demonstrated an ultrasensitive optical electric field sensor (OES) by hybrid cascaded configuration of a Fabry-Perot interferometer (FPI) and a fiber Sagnac interferometer (FSI). The FPI is fabricated by a LiNbO3 (LN) crystal with length of 1.04 mm, while the FSI consists of a certain length of Panda polarization-maintain fiber (PMF). The sensitivity of the
${E}$
-field can be significantly enhanced through the utilization of high-order harmonic Vernier effect (HVE) by employing two interferometers. The experimental results show that the sensor is capable of measuring
${E}$
-field 0–1.01 V/
$\mu \text{m}$
, with the sensitivity of 4.38 nm/E (40 times that of a single FPI). The results of many experiments demonstrate the sensor has excellent stability, with the
${E}$
-field sensitivity stabilized at 4.38 ± 0.0016 nm/E and a repeatability error of only
$3.65\times 10^{-{4}}$
. The sensor exhibits a low detection limit (DL) of merely
$1.13\times 10^{-{2}}$
E. Additionally, the temperature compensation of
${E}$
-field sensors can be achieved by utilizing the sensitivity coefficient matrix. The proposed
${E}$
-field sensor overcomes the inherent limitation of half-wave voltage for measuring
${E}$
-field range, eliminating the need to incorporate a 1/4 wave plate into its structure. And it fundamentally eliminates disturbances caused by variations in light intensity on the sensor output. Applications using this sensor confirmed that it is expected to find widespread use in measurements of intense
${E}$
-fields.