Seven-core fiber torsion sensor with microcavity structure based on intensity measurement

A seven-core fiber torsion sensor with microcavity structure based on intensity measurement is proposed. It is composed of a seven-core fiber (SCF) and two multi-mode fibers (MMF). The first end of the SCF has a microcavity structure. Because the mode fields between the MMF and SCF do not match at the splicing point, the phenomenon of mode interference will be formed between cladding modes and core modes. Experimental results show that in a clockwise situation, the intensity of transmission spectrum increases in the torsion range of 0 similar to 70 degrees, the torsion sensitivity is 0.098 dB/degrees. And in a counterclockwise situation, the intensity of transmission spectrum decreases, the torsion sensitivity is 0.103 dB/degrees. The sensor has a simple structure and easy to fabricate, so it has wide application prospects in the field of torsion sensing.