Resonance-based optical fiber refractometers

Here, it is presented a study of optical fiber refractometers based on resonances supported by different thin-film coatings. These coatings consist of different materials, such as noble metals and metal oxides fabricated onto the core of the optical fibers. The dielectric constants of the deposited materials determine the presence of the resonances. Thus, noble metals, such as gold and silver, thanks in part to their negative real part of the optical permittivity enable the generation of surface plasmon resonances (SPR). Meanwhile, conductive metal oxides, such as titanium dioxide (TiO₂) and indium tin oxide (ITO), with a positive real part of its optical permittivity make it possible to produce lossy mode resonances (LMR). Gold, silver, TiO₂ and ITO refractometers show sensitivities of 1468, 3617, 114 and 1546 nm/refractive index unit (RIU) respectively. Fabricated devices present a promising platform for the fabrication of multipurpose sensors by the addition of the adequate coating.