Plasmonic sensors based on tilted Bragg gratings in multicore optical fibers

Abstract

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.

Novel Specialty Optical Fibers and Applications

“…The mid-IR MFs could further broaden the frequency combs by SC generation when the generated SC maintains coherence with the pump laser. In 2012, Marandi et al used a subharmonic OPO and subsequent SC generation in the tapered MF to convert the pulses of a conventional 1.5-micrometer frequency comb source to mid-IR [106]. The spectrum of the MF output extended from 2.2 to 5 µm at 40 dB below the peak (Figure 7e1).…”

“…The result shows that for refractive index sensing, the higher the tilted angle the higher the sensor sensitivity. Tilted fiber Bragg gratings in 4-core fibers have also been used to develop refractometers [106]. Thanks to the reduction in the core-surrounding medium distance in the multicore fiber, higher sensitivity can be achieved in comparison with their counterparts in SMF.…”

Analysis of Demodulation Methods of Tilted Fibre Bragg Gratings Based on the Local Shift of the Cladding Mode Group

“…It is mainly SRI measurements that lead to the creation and research of new structures and applications of TFBGs. The development of measurement methods for TFBGs also uses special types of optical fibres [3]. Unlike other fibre optic methods for determining SRI, TFBGs do not require removing the fibre cladding or implementing a special sensor head [4].…”

Multicore Fiber Bending Sensors with High Sensitivity Based on Asymmetric Excitation Scheme

“…The lights are confined within the core for uniform FBGs, allowing them to be used for physical measurements of temperature, strain, or pressure. However, for special applications such as biosensing, interactions with the surrounding medium are required, and are usually obtained using cladding mode excitation [ 11 , 12 ]. On the other hand, fiber interferometers are also good options for bending sensing, since the angular displacement can lead to variations in the optical path difference (OPD) between the interfering optical beams to change the resonant wavelengths [ 13 ].…”