Optical frequency domain reflectometry cross-interference noise suppression method based on the Kramers-Kronig relation

Optical frequency domain reflectometry (OFDR) is a distributed measurement and sensing technology that is usually characterized by its high precision, high spatial resolution, and high sensitivity. However, cross-interference due to the random interference amongst Rayleigh backscattering(RBS) in sensing fibers may lead to crosstalk and raise of the noise floor, which degrades measurement accuracy. In this work, we propose an OFDR demodulation scheme based on Kramers- Kronig (KK) relation. Based on a verified establishment of KK relation in typical OFDR measurement process, a nonlinear mapping from the beat-signal amplitude to the phase is exploited by reconstructing the complex beat signal via KK relation. It allows accessing to the complex beat note spectrum with single-end photo-detection and enables phase demodulation. Experimental results show that the accurate estimation for the phase spectrum among the beat note frequency components. It also verified that with a reduced hardware complexity, the suppression for coherent fading and cross-interference noise can be helpful for practical sensing applications.