Wide-range OFDR strain sensor based on the femtosecond-laser-inscribed weak fiber Bragg grating array

A wide-range OFDR strain sensor was demonstrated based on femtosecond-laser-inscribed weak fiber Bragg grating (WFBG) array in standard SMF. A WFBG array consisting of 110 identical WFBGs was successfully fabricated along a 56 cm-long SMF. Compared with SMF, the cross-correlation coefficient of WFBG array was improved to 0.9 under the strain of 10,000 µε. The position deviation under the strain of 10,000 µε, i.e., 2.5 mm, could be accurately obtained and compensated simply by using peak finding algorithm. The maximum measurable strain of single- and multi-point strain sensing was up to 10,000 µε without using any additional algorithms, where the sensing spatial resolution was 5 mm.