Plasmonic sensors based on tilted Bragg gratings in multicore optical fibers

Bare and gold-coated tilted fiber Bragg gratings (TFBGs) can nowadays be considered as a mature technology for volume and surface refractometric sensing, respectively. As for other technologies, a continuous effort is made towards the production of even more sensitive sensors, thereby enabling a high-resolution screening of the surroundings and the possible detection of rare events. To this aim, we study in this work the development of TFBG refractometers in 4-core fibers. In particular, we show that the refractometric sensitivity of the cut-off mode can reach 100 nm/RIU for a bare grating. Using another demodulation method, a tenfold sensitivity increase is obtained when tracking the extremum of the SPR (surface plasmon resonance) envelope for a gold-coated TFBG configuration. Immobilization of DNA probes was performed as a proof-of-concept to assess the high surface sensitivity of the device. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Bare and gold-coated tilted fiber Bragg gratings (TFBGs) are mature technologies for volume and surface refractometric sensing. Efforts are being made to produce more sensitive sensors for high-resolution screening of surroundings and detection of rare events. This study explores the development of TFBG refractometers in 4-core fibers, achieving high sensitivity and surface sensitivity with DNA probes immobilization as proof.