Polymer optical fiber sensors—a review

Abstract

Polymer optical fibers (POFs) have significant advantages for many sensing applications,including high elastic strain limits, high fracture toughness, high flexibility in bending, highsensitivity to strain and potential negative thermo-optic coefficients. The recent emergenceof single-mode POFs has enabled high precision, large deformation optical fiber sensors.This article describes recent advances in both multi-mode and single-mode POFbased strain and temperature sensors. The mechanical and optical propertiesof POFs relevant to strain and temperature applications are first summarized.POFs considered include multi-mode POFs, solid core single-mode POFs andmicrostructured single-mode POFs. Practical methods for applying POF sensors, includingconnecting and embedding sensors in structural materials, are also described. Recentdemonstrations of multi-mode POF sensors in structural applications based on newinterrogation methods, including backscattering and time-of-flight measurements, areoutlined. The phase–displacement relation of a single-mode POF undergoing largedeformation is presented to build a fundamental understanding of the response ofsingle-mode POF sensors. Finally, this article highlights recent single-mode POFbased sensors based on polymer fiber Bragg gratings and microstructured POFs.