Fiber-optic axial-strain sensor based on in-cavity micro-bubble fabry-perot interferometer

In this paper, a novel fiber-optic axial-strain sensor based on a micro-cavity Fabry-Perot interferometer (FPI) is proposed and experimentally realized. This micro-cavity FPI is mainly composed of a micro-air-bubble in a tapered hollow-core fiber fabricated by arc-discharged multiple-tapering technique. The experimental results show that the maximum sensitivity of axial-strain can reach ∼8.9 p.m./με in the range from 0 to 1100 με with high linearity. Additionally, high repeatability and ultra-low crosstalk of temperature (∼0.078 με/°C) are demonstrated, which brings a detection accuracy of 1.5 %. With the merits of compactness, low cost and ease of fabrication, the proposed sensor is very promising and potential to high precision axial-strain related measurement.