A four core fiber temperature and strain dual parameter sensor based on T-shaped taper

Abstract

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper is proposed and prepared. The sensor is composed of single-mode fiber (SMF), multi-mode fiber (MMF), and four core fiber (FCF). Among them, MMF plays a role in beam expansion, and FCF is tapered and fused with SMF to form a T-shaped taper structure, thereby preparing a sensor based on Mach Zehnder interference principle. When the external environmental temperature and strain change, due to thermal effect and elastic optical effect, the refractive index of the FCF cladding and fiber core changes differently, resulting in shift in the interference spectrum. Based on the temperature and strain sensitivity at different interference valleys, the temperature and strain dual parameter matrix equation of the sensor can be obtained. The experimental results indicate that when the temperature rises within the range of 30 ℃ to 90 ℃, the sensor spectrum shows a red shift phenomenon, and the maximum temperature sensitivity can reach 55 pm/ ℃. When the strain increases within the range of 0 με∼ 2000 με, the transmission spectrum of the sensor exhibits a blue shift phenomenon, and the maximum strain sensitivity can reach −2.6 pm/ με. Finally, based on the experimental results, the matrix equation for dual parameter sensing can be obtained. This sensor is easy to manufacture and has high sensitivity. It can measure sensing parameters normally in micro magnetic and micro electric field environments.