Self-referenced antiresonant reflecting guidance mechanism for directional bending sensing with low temperature and strain crosstalk

A sensitive one-dimensional vector bending fiber-optic sensor based on self-referenced antiresonant reflecting guidance mechanism has been proposed and experimentally demonstrated. Two symmetric air holes in the hollow-core photonic crystal fiber (HCPCF) were infiltrated with refractive index matching liquids with different refractive indices, which formed a self-referenced anti-resonant reflecting optical waveguide. The bending of the HCPCF induces a wavelength shift of lossy dip in the transmission spectrum. Specially, the one-dimensional bending orientation can be detected through the wavelength interval between two lossy dips due to the asymmetric refractive index change of the silica cladding for two resonators. The bending sensitivities are 4.86 and −4.84 nm/m⁻¹ for the curvatures of the 0° and 180° bending orientations in a bending range from 0 to 0.88 m⁻¹, respectively. Moreover, the temperature and strain crosstalk of the proposed sensor can be eliminated through the compensated self-referenced anti-resonant reflecting optical waveguide. The proposed fiber sensor can be used for the monitoring of the structural health of infrastructures.