Distributed optical fiber sensing of micron-scale particles

Abstract

Distributed sensing of micron-scale particles is achieved with an exposed-core microstructured optical fiber using optical frequency domain reflectometry. The reference and sample signals of the interferometer are generated in the same fiber path, which gives this fully fiber-integrated sensor the potential to be used as a portable probe for in-vivo sensing. This sensing concept has great advantages over reported single-point fiber sensors due to its distributed sensing property. We demonstrate the technique using 10 μm polystyrene beads, by detecting their locations along the fiber through backscatter of the exposed-core fiber’s evanescent field. A simplified theoretical model is proposed to estimate the relationship between the particle’s size and detection distance after considering the system’s inherent losses. The proposed sensing platform offers opportunities for distributed sensing of biological targets.