Sensing properties of asymmetric double-layer-covered tapered fibers

Abstract

A novel, to our knowledge, device based on a tapered optical fiber with a double-layer deposition including a metallic media is presented, and its properties are studied. The main novelty of the device consists of the introduction of a dielectric layer, whereas the systems depicted in the literature are simply metalcoated tapered fibers. The presence of the dielectric layer permits one to tune the response of the device to the refractive index of the surrounding medium. We have proved the suitability of this scheme for refractive-index sensing by depicting two measurement modes, namely, total power attenuation and spectral transmittance.

Surface plasmon resonance sensors based on uniform-waist tapered fibers in a reflective configuration

“…The RI of the mixture depends on the ethylene glycol concentration according to the following empirical law 13 :…”

“…10,13 The first one is decreasing the fiber diameter so that we can reach the evanescent field of the mode propagated by the unperturbed fiber. We follow the procedure developed by Kenny et al, 12 the so-called traveling burner.…”

“…We have chosen a first layer of Al 8 nm thick and a second layer of TiO 2 60 nm thick. The Al shows better adherence than Au to SiO 2 fibers, and it is best suited for SPR at wavelengths in the 600-1000 nm range, while the TiO 2 layer is used to tune the SPR response to the refractive index range of interest, 13,14 which relies on the interval 1.32-1.40 of aqueous solutions at wavelengths in the visiblenear-infrared spectral range.…”

“…10 With this method, it is possible to obtain uniform-waist tapered (UWT) fibers with a controlled length and a waist diameter in a highly reproducible way. Furthermore, SPR sensors with UWT fibers have shown a high sensitivity and dynamic range 10,[13][14][15] and could be the best option when the sample volume is not a critical parameter.…”

Surface plasmon interferometer in silicon-on-insulator: novel concept for an integrated biosensor

“…The resonance wavelength or resonance refractive index of SPR sensors can be tuned to some extent by using buffer layers between the dielectric waveguide layer and the gold layer or by choosing the appropriate metal [2,4,5,13]. The fact that our device is based on interference rather than phase-matching allows one to tune the response of the device much more easily.…”