Open Access
Generation of lossy mode resonances by deposition of high-refractive-index coatings on uncladded multimode optical fibers
(IOP Publishing Ltd, 2010) Del Villar, Ignacio; Ruiz Zamarreño, Carlos; Sánchez Zábal, Pedro; Hernáez Sáenz de Zaitigui, Miguel; Fernández Valdivielso, Carlos; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A comparative study of lossy mode resonances generated by depositing two different materials is presented. The two materials selected are indium tin oxide (ITO) and indium oxide. The two materials present different dielectric dispersion, which leads to the generation of single-peak lossy mode resonances with the ITO coated optical fibers and dual-peak lossy mode resonances with the In2O3 coated optical fibers. The obvious advantage of a dual-peak based measurement in the sensors field is enhanced by a sensitivity increase observed in sensors based on In2O3 if compared with those based on ITO. These characteristics are analyzed both theoretically and experimentally.
Open Access
An antibacterial coating based on a polymer/sol-gel hybrid matrix loaded with silver nanoparticles
(Springer, 2011) Rivero Fuente, Pedro J.; Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Ruiz Zamarreño, Carlos; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work a novel antibacterial surface composed of an organic-inorganic hybrid matrix of tetraorthosilicate and a polyelectrolyte is presented. A precursor solution of tetraethoxysilane (TEOS) and poly(acrylic acid sodium salt) (PAA) was prepared and subsequently thin films were fabricated by the dip-coating technique using glass slides as substrates. This hybrid matrix coating is further loaded with silver nanoparticles using an in situ synthesis route. The morphology and composition of the coatings have been studied using UV-VIS spectroscopy and atomic force microscopy (AFM). Energy dispersive X-ray (EDX) was also used to confirm the presence of the resulting silver nanoparticles within the thin films. Finally the coatings have been tested in bacterial cultures of genus Lactobacillus plantarum to observe their antibacterial properties. It has been experimentally demonstrated that these silver loaded organic-inorganic hybrid films have a very good antimicrobial behavior against this type of bacteria.
Open Access
Etched and nanocoated single-mode multimode single-mode (SMS) fibers for detection of wind turbine gearbox oil degradation
(IEEE, 2019) Del Villar, Ignacio; Goñi Carnicero, Jaime; Vicente Gómara, Adrián; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua, 2017/PI044
The application of an etching process in a single-mode multimode single-mode (SMS) fiber allows monitoring the change of refractive index of wind turbine gearbox oil due to temperature and degradation with a limitation at short temperatures, where the transmission and attenuation bands in the optical spectrum fade. The application of a black tin oxide nanocoating solves this issue and allows tuning the refractive index region where the sensitivity is maximum. The SMS was designed for operating at short wavelengths, where the setup is less expensive. The experimental results were contrasted with a theoretical analysis developed with FIMMWAVE, which allowed understanding better the phenomena involved in the experiments.
Open Access
Long period fiber gratings with overlay of variable refractive index
(IEEE, 2005) Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
A theoretical analysis is presented of a long-period fiber grating (LPFG) with an overlay of variable refractive index. The highest sensitivity of the resonance wavelengths to variations in the refractive index of the overlay can be optimized. There are two key points for a good design: the selection of an overlay refractive index close to that of the cladding of the LPFG and the overlay thickness. The problem is analyzed with a numerical method based on coupled-mode theory.
Open Access
Generation of surface plasmon resonance and lossy mode resonance by thermal treatment of ITO thin-films
(Elsevier, 2014) Del Villar, Ignacio; Ruiz Zamarreño, Carlos; Hernáez Sáenz de Zaitigui, Miguel; Sánchez Zábal, Pedro; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Silicon wafers coated with IndiumTinOxide (ITO) by application of sputtering technique have been characterized after different post-annealing techniques, showing that this last factor is critical for the quality of the thin-film and for the creation and tuning of both surface plasmon resonances and lossy mode resonances. By adequate selection of the ITO thin-film thickness both resonances can be tracked in the same spectrum, which can be used in sensor and optical communications fields.
Open Access
Optimization of sensors based on multimode interference in single-mode–multimode– single-mode structure
(IEEE, 2013) Del Villar, Ignacio; Socorro Leránoz, Abián Bentor; Corres Sanz, Jesús María; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
By coating a single-mode–multimode–single-mode (SMS) structure with a complex refractive index thin-film the central wavelength of the transmission and attenuation bands of the optical spectrum can be shifted. By adequate selection of multimode segment length and diameter, the thin-film thickness and the thin-film refractive index, the sensitivity of the device to the surrounding medium refractive index, the thickness of the thin-film or the refractive index of the thin-film can be optimized. Experimental results are corroborated numerically with the transfer matrix method.
Open Access
A comparative study of two different approaches for the incorporation of silver nanoparticles into layer-by-layer films
(Springer, 2014) Rivero Fuente, Pedro J.; Goicoechea Fernández, Javier; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, a comparative study about the incorporation of silver nanoparticles (AgNPs) into thin films is presented using two alternative methods, the in situ synthesis process and the layer-by-layer embedding deposition technique. The influence of several parameters such as color of the films, thickness evolution, thermal post-treatment, or distribution of the AgNPs along the coatings has been studied. Thermal post-treatment was used to induce the formation of hydrogel-like AgNPs-loaded thin films. Cross-sectional transmission electron microscopy micrographs, atomic force microscopy images, and UV-vis spectra reveal significant differences in the size and distribution of the AgNPs into the films as well as the maximal absorbance and wavelength position of the localized surface plasmon resonance absorption bands before and after thermal post-treatment. This work contributes for
Open Access
D-shape optical fiber pH sensor based on lossy mode resonances (LMRs)
(IEEE, 2016-01-07) Zubiate Orzanco, Pablo; Ruiz Zamarreño, Carlos; Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
The fabrication and characterization of an optical fiber pH sensor based on Lossy Mode Resonances (LMRs) is presented. PAH/PAA polymeric thin-films fabricated onto side-polished D-shaped optical fibers are used as LMR supporting coatings. The thickness of PAH/PAA coatings can be modified as a function of the external medium pH. As a consequence of this variation, the effective refractive index of the structure will change, producing a shift of the LMR. The fabricated sensor has been used to measure pH from 4.0 to 5.0. This pH sensor showed a sensitivity of 101.3 nm per pH unit, which means a resolution of ~6×10-4 pH units by using a conventional communications Optical Spectrum Analyzer (OSA), which is an improvement over commercial pH sensors.
Open Access
Deposition of coatings on long-period fiber gratings: tunnel effect analogy
(Springer, 2006) Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
The sensitivity of Long-period fiber gratings (LPFGs), coated with high-refractive-index thin film overlays, to the refractive index and the thickness of the overlay, and to the ambient refractive index, can be enhanced with a design based on a two-overlay coating of an LPFG. The first overlay of lower refractive index than the cladding affects the guidance of a cladding mode in the second overlay of higher refractive index than the cladding. This causes a more abrupt cladding modal redistribution than with the deposition of a unique high-refractive-index overlay. The phenomenon is analyzed with a method based on a vectorial analysis of modes and the application of coupled mode theory.
Open Access
High sensitivity humidity sensor based on cladding-etched optical fiber and lossy mode resonances
(Elsevier, 2016) Ascorbe Muruzabal, Joaquín; Corres Sanz, Jesús María; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work a high sensitivity optical fiber humidity sensor (OFHS) is presented. The configuration chosen for this purpose is a cladding-etched single mode optical fiber (CE-SMF) coated with a thin film of tin oxide (SnO2). The etching has been made using hydrofluoric acid (HF) and the coating has been fabricated by means of sputtering. Tin oxide was used to build the nano-coating which produces the Lossy Mode Resonance (LMR) and works as sensitive material. Theoretical and experimental results are shown and compared. The device was tested using a climatic chamber in order to obtain the response of the OFHS to relative humidity. Changes greater than 130 nm have been obtained for relative humidity varying from 20% to 90%, which gives a sensitivity of 1.9 nm/%RH.