Multicore Fiber Enabled Fading Suppression in φ-OFDR Based High Resolution Quantitative DVS

Coherent fading has long been regarded as a critical issue in phase-sensitive optical frequency domain reflectometry (
$\varphi $
-OFDR) based distributed fiber-optic sensing. Here, we report on an approach for fading noise suppression in
$\varphi $
-OFDR using multi-core fiber (MCF). By exploiting the independent nature of the randomness in the distribution of the refractive index in each of the cores, the phase fluctuations due to the fading phenomena can be effectively alleviated by applying a weighted vectorial averaging for the Rayleigh backscattering (RBS) traces obtained from each of the cores with their distinct fading distribution. The proposed
$\varphi $
-OFDR with a commercial seven-core fiber has achieved quantitative distributed vibration sensing with ~2.2 nm length precision and 2 cm sensing resolution along a 500 m MCF, corresponding to a resolution-to-range factor as high as
${\sim }4\times 10^{-5}$
. Featuring long distance, high sensitivity, high spatial resolution, and fading robustness, it shows promising potential in various sensing techniques for a wide range of practical scenarios.