High-resolution fiber laser sensor for strain and temperature measurements using matrix demodulation

Structural health monitoring demands high-resolution and demodulation measurements of strain and temperature simultaneously. Here, we propose an erbium-doped fiber ring laser (EDFRL) which is integrated with a polarization maintaining fiber inserted Sagnac interferometer (PMF-SI) and a fiber Bragg grating (FBG) to achieve this purpose. Leveraging the narrow full width at half maximum (FWHM) and high coherence of the EDFRL, the proposed sensor achieves ultrahigh resolution (R) of 0.015 °C for temperature measurement and 1.96 με for strain measurement respectively, surpassing most reported fiber laser-based sensors. A matrix is utilized to decouple the cross-sensitivity between temperature and strain owing to the e differential responses of PMF-SI and FBG. The detection errors are < 0.183 °C for temperature measurement and < 15 με for strain measurement, respectively. Owing to the high-resolution and decoupling method, the proposed sensor can measure temperature and strain simultaneously with good performance.