High sensitivity strain sensor based on cascaded cladding mode resonant double-clad fiber and simple mode fiber

A high sensitivity strain sensor based on cascaded cladding mode resonant double-clad fiber (DCF) and simple mode fiber is proposed. The basic principle of the sensor is analyzed, and the preparation of the sensor is performed. In different length of double-clad fiber, the strain sensing characteristics are analyzed detailedly. Experimental results show that, as the length of the connected double-clad fiber increases, the trough of the resonant spectrum will gradually increase. That is, the length of the access DCF is inversely proportional to the free spectral range. With the increase of tensile force, the resonance spectrum is blue shift, and the tension sensitivity can be up to -1.87nm/mε.