Rayleigh scattering-based single mode-graded index multimode-coreless fiber structure for distributed liquid detection

Abstract

Liquid sensing is crucial in numerous industrial contexts, from chemical processing to power transformers, ensuring safety and operational optimization. While electrochemical liquid sensors are common, they pose safety risks, especially when monitoring hazardous liquids. Optical fiber sensors, with advantages like immunity to electromagnetic fields and resistance to chemical corrosion, present a safer alternative. These sensors are primarily used for detecting pipeline oil leakages and liquid level sensing. However, current sensors face challenges in detecting liquid spills across multiple locations and require improved spatial resolution. This paper presents what we believe to be a novel single mode-graded index multimode-coreless fiber sensing structure that directly interacts with liquids. Integrated with a distributed optical fiber sensing system, this sensor can detect liquid droplets with high precision, as demonstrated by the successful identification and size estimation of four consecutive oil droplets. Our approach offers an innovative solution for distributed liquid droplet detection and it paves the way for industrial liquid detecting applications.