Coupled-core fiber Bragg gratings for low-cost sensing

[EN] Sensors based on Bragg gratings inscribed in conventional single mode fibers are expensive due to the need of a sophisticated, but low-speed, interrogation system. As an alternative to overcome this issue, in this work, it is proposed and demonstrated the use of coupled-core optical fiber Bragg gratings. It was found that the relative reflectivity from such gratings changed when the coupled-core fiber was subjected to point or periodic bending. This feature makes the interrogation of such gratings simple, fast, and cost-effective. The reflectivity changes of the gratings are attributed to the properties of the supermodes supported by the coupled-core fiber. As potential applications of the referred gratings, intensity-modulated vector bending and vibration sensing are demonstrated. We believe that the results reported here can pave the way to the development of many inexpensive sensors. Besides, coupled-core fiber Bragg gratings may expand the use of grating technology in other areas.This work is part of the Projects No. PGC2018-101997-B-I00 and RTI2018-094669-B-C31 funded by the MCIN/AEI/10.13039/501100011033/and FEDER, Una manera de hacer Europa; and the scholarship PAID-01-18 Granted by the Universitat Politecnica de Valencia