High Sensitivity Strain Sensors Using Four-Core Fibers through a Corner-Core Excitation

Lina Suo, Ya-Pei Peng, Cheng-Kai Yao, Shijie Ren, Xinhe Lu, Nan-Kuang Chen
2022 Micromachines  
A weakly-coupled multicore fiber can generate supermodes when the multi-cores are closer to enter the evanescent power coupling region. The high sensitivity strain sensors using tapered four-core fibers (FCFs) were demonstrated. The fan-in and fan-out couplers were used to carry out light coupling between singlemode fibers and the individual core of the FCFs. A broadband lightsource from superlumminescent diodes (SLDs) was launched into one of the four cores arranged in a rectangular
more » ... on. When the FCF was substantially tapered, the asymmetric supermodes were produced to generate interferences through this corner-core excitation scheme. During tapering, the supermodes were excited based on a tri-core structure initially and then transited to a rectangular quadruple-core structure gradually to reach the sensitivity of 185.18 pm/μԑ under a tapered diameter of 3 μm. The asymmetric evanescent wave distribution due to the corner-core excitation scheme is helpful to increase the optical path difference (OPD) between supermodes for improving the strain sensitivity.
doi:10.3390/mi13030431 pmid:35334723 pmcid:PMC8949566 fatcat:cll4nblpdbak7h6ke3ss4kakie