Simultaneous measurement of micro-displacement and temperature based on balloon-like interferometer and fiber Bragg grating

Abstract

An optical fiber sensor based on balloon-like interferometer and fiber Bragg grating (FBG) for simultaneous measurement of micro-displacement and temperature has been presented and experimentally investigated. The single-mode fiber (SMF) with coating stripped is designed into a balloon-like shape to form a modal interferometer. The interference occurs between the core mode and cladding mode induced by the bending. With the micro-displacement increasing, the radius of balloon-like interferometer changes, which results in the variation of interference fringe of balloon-like interferometer, while the Bragg wavelength of FBG remains the same. With the change of temperature, the interference fringe of balloon-like interferometer and Bragg wavelength of FBG will shift. Thus the simultaneous measurement of micro-displacement and temperature can be achieved. From the experimental results, sensitivities of the balloon-like interferometer for the micro-displacement and temperature are 180 pm/μ m and 105 pm/°C.