Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors

Abstract

Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO 2 ) and aluminum oxide (Al 2 O 3 ) with thicknesses from 30 to 220 nm have been evaluated numerically and compared. TiO 2 films were found to be the most promising candidates for the tuning of FPI reflectivity. In order to verify and illustrate the results of modelling, TiO 2 films with the thickness of 80 nm have been deposited on the tip of a single-mode optical fiber by atomic layer deposition (ALD). The thickness, the structure, and the chemical properties of the films have been determined. The ability of the selected TiO 2 films to modify the reflectivity of the Fabry-Pérot cavity, to provide protection of the fibers from aggressive environments, and to create multi-cavity interferometric sensors in FPI has then been studied. The presented sensor exhibits an ability to measure refractive index in the range close to that of silica glass fiber, where sensors without reflective films do not work, as was demonstrated by the measurement of the refractive index of benzene. This opens up the prospects of applying the investigated sensor in biosensing, which we confirmed by measuring the refractive index of hemoglobin and glucose.

A Fiber Optic Interferometric Sensor Platform for Determining Gas Diffusivity in Zeolite Films

“…This FOI sensor technology may be improved by employing CCD spectrometers to monitor frequency shift with high speed for measuring zeolites and molecules where large diffusivity values exist. Furthermore, the principle of the diffusivity measurement demonstrated in this study may be applied to the recently developed film-coated endface cavity FOIs [ 28 , 29 ] for determination of molecular and ionic diffusivities in liquid phases.…”

Tailoring the Optical Parameters of Optical Fiber Interferometer With Dedicated Boron‐Doped Nanocrystalline Diamond Thin Film

“…Optical fiber interferometers are commonly used as sensors in many areas of human life because of their small size, low weight, and very good metrological parameters . The metrological parameters of optical fiber interferometer (spatial resolution, stability, accuracy) are determined mainly by the visibility of the measured signal spectrum.…”

Investigation of A Slow-Light Enhanced Near-Infrared Absorption Spectroscopic Gas Sensor, Based on Hollow-Core Photonic Band-Gap Fiber

“…Conventional absorption spectroscopic sensor systems [ 3 , 4 , 5 ], such as cavity-enhanced absorption spectroscopy, are ultrasensitive, but are large and have a heavy tabletop instrument that requires a large gas cell with a long absorption path length. Recently, there has been an increasing emphasis on the miniaturization of chemical analysis systems and optics, such as lab-on-a-chip microsystems [ 6 , 7 , 8 ] and fiber optic sensors [ 9 , 10 ]. In particular, miniaturized gas sensors based on photonic hollow-core crystal (PHC) waveguides are receiving attention for achieving superior performance in optical signal processing and sensing applications [ 11 , 12 , 13 ].…”