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

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/degrees C in the range of 0.36-1.61 nm/m-1, 0-57.12 rad/m, 30- 100 degrees 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.

Automated summary

We have proposed and 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) using a fusion splicer and a microscope. It has high sensitivity and ability to measure curvature, torsion, and temperature in a compact structure, making it suitable for harsh environment applications.