Cascaded multicore fiber interferometers for enhanced bending sensing based on the Vernier effect.

In this paper, cascaded modal interferometers constructed by strongly-coupled seven-core fiber (SC-SCF) with different lengths are demonstrated for enhanced bending sensing based on Vernier effect. The free spectral range (FSR) of a single SC-SCF interferometer is determined by the length of SC-SCF. Two SC-SCF interferometers with different FSRs are cascaded, in which, one functions as the sensor while the other functions as the reference.