Seven-core fiber embedded ultra-long period grating for curvature, torsion or temperature sensing

• Published in: Optics communications Vol. 536; p. 129351
• Main Authors: Wang, Xinyu, Wang, Yu, Ling, Qiang, Zhang, Qishuang, Luo, Weixuan, Yu, Zhangwei, Tao, Chenning, Jiang, Xiuli, Chen, Haiyun, Guan, Zuguang, Chen, Daru
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2023
• Subjects: Curvature; Long period fiber grating; Optical fiber sensor; Seven-core fiber; Torsion; Long period fiber grating; Seven-core fiber; Curvature; Torsion; Optical fiber sensor
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2023.129351

We have proposed and experimentally demonstrated a novel seven-core fiber (SCF) embedded ultra-long period grating (EU-LPFG) structure for curvature, torsion or temperature sensing. The EU-LPFG is fabricated by periodically splicing a SCF and a single mode fiber (SMF) just by using a fusion splicer and a microscope. Due to the periodic refractive index modulation, the EU-LPFG forms two resonant peaks in only 8-period SMF-SCF structure with a total length of 5.0 mm, has high curvature, torsion or temperature sensitivity of 31.26 nm/m−1, 0.19 nm/(rad/m) and 0.53 nm/°C in the range of 0.36–1.61 nm/m−1, 0–57.12 rad/m, 30–100 °C, respectively. According to the compact structure, simple fabricated method, high curvature and torsion sensitivity and ability to measure temperature, the proposed novel SCF-embedded EU-LPFG can be used as the competitive all-fiber sensor in harsh environment applications. •A novel, low-cost sensor based on seven-core fiber embedded ultra-long period grating has been proposed and discussed in detail.•The sensor exhibits excellent sensing performance, with a maximum curvature sensitivity of 31.26 nm/m−1, a torsion sensitivity of 0.19 nm/(rad/m) and a temperature sensitivity of 0.53 nm/°C•The sensor is compact and cheap to make.