Open Access
Nanocoated optical fibre for lossy mode resonance (LMR) sensors and filters
(IEEE, 2015) Del Villar, Ignacio; Arregui San Martín, Francisco Javier; Corres Sanz, Jesús María; Bariáin Aisa, Cándido; Goicoechea Fernández, Javier; Ruiz Zamarreño, Carlos; Elosúa Aguado, César; Hernáez Sáenz de Zaitigui, Miguel; Rivero Fuente, Pedro J.; Socorro Leránoz, Abián Bentor; Urrutia Azcona, Aitor; Sánchez Zábal, Pedro; Zubiate Orzanco, Pablo; López Torres, Diego; Acha Morrás, Nerea de; Ascorbe Muruzabal, Joaquín; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Nanometer scale coatings with a complex refractive index deposited on optical fibre permit to obtain attenuation bands in the transmission spectrum, whose central wavelength coincides with the moment when a mode guided in the optical fibre cladding starts to be guided in the coating. Due to the complex refractive index of the coating, the guided mode is a lossy mode. Consequently, these attenuation bands receive the name of lossy mode resonances. This phenomenon can be used for development of ultra-high sensitivity photonic devices (for detection, among others, of volatile organic compounds, pH and refractive index) or for optical filtering. In this work, rules for adequate design are indicated based on numerical results obtained with FIMMWAVE and on experimental results that corroborate the theoretical predictions.
Open Access
Improving the width of lossy mode resonances in a reflection configuration D-shaped fiber by nanocoating laser ablation
(Optical Society of America, 2020) Fuentes Lorenzo, Omar; Vaiano, Patrizio; Del Villar, Ignacio; Corres Sanz, Jesús María; 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
The full width at half maximum (FWHM) of lossy mode resonances (LMRs) in the optical spectrum depends on the homogeneity of the thin film deposited. In this Letter, a method for improving the FWHM is applied for an LMR generated by a D-shaped optical fiber in reflection configuration. For this purpose, three samples with different attenuation were deposited with DC sputtering thin films of SnO2−x, and a further controlled immersion of the samples in water was performed. A laser-cleaner method was used to improve the FWHM characteristics of one of the samples from 106 to 53 nm. This improvement can be applied to thin-film-based sensors where there is a problem with the inhomogeneity of the coating thickness. Moreover, with this technique, it was proved that a coated length of just 3–4 mm permits the generation of an LMR, with implications for the miniaturization of the final device.
Open Access
Multi-sensing platform design with a grating-based nanostructure on a coverslip substrate
(Springer, 2023) Imas González, José Javier; Del Villar, Ignacio; Ruiz Zamarreño, Carlos; Mukhopadhyay, Subhas C.; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Two different thin film designs with a grating pattern are simulated on a soda lime coverslip, which acts as optical waveguide, with the purpose of generating both a lossy mode resonance (LMR) in transmission and reflection bands. This way both phenomena can be made sensitive to different parameters, leading to a multi-sensing device. The first design consists of a grating patterned in a SnO2 thin film deposited on the coverslip. The performance of the device in both transmission and reflection is numerically studied in air for different values of the grating pitch. Small grating pitches (in the order of the µm) are more suitable for generating the reflection bands while larger values (500 µm or more) are required to produce the LMR, when the reflection bands are no longer visible. Due to the inability to obtain both phenomena with this design, a second design is assessed, where the grating is combined with a section of constant thickness. In this case the desired response is obtained, which opens the path to use this device for multi-sensing applications, measuring several parameters at the same time.
Open Access
Tunable sensitivity in long period fiber gratings during mode transition with low refractive index intermediate layer
(IEEE, 2022) Del Villar, Ignacio; Montoya-Cardona, Jorge; Imas González, José Javier; Reyes-Vera, Erick; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Cruz, José Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Double-clad fibers where the second cladding has a lower refractive index than the first cladding, prove to be ideal structures for potentiating and tuning the sensitivity in long-period fiber gratings (LPFGs) operating in mode transition. When a thin film is deposited on the optical fiber, the second cladding performs acts as a barrier that initially prevents the transition to guidance in the thin film of one of the modes guided in the first cladding. Finally, the transition to guidance occurs with a sensitivity increase, in analogy to the tunnel effect observed in semiconductors. This improvement has been demonstrated both as a function of the thin film thickness and the surrounding medium refractive index, with enhancement factors of 4 and 2, respectively. This idea reinforces the performance of LPFGs, adding a new degree of freedom to the mode transition and the dispersion turning point phenomena. Moreover, the control of the variation of the effective index of cladding modes could be applied in other structures, such as tilted-fiber gratings or evanescent wave sensors.
Open Access
Generation of lossy mode resonances in planar waveguides toward development of humidity sensors
(IEEE, 2019) Fuentes Lorenzo, Omar; Corres Sanz, Jesús María; Matías Maestro, Ignacio; Del Villar, Ignacio; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Lossy mode resonances (LMRs) are typically obtained with optical fibre. The Kretschmann configuration is an alternative but LMRs are generated with angles approaching grazing incidence. In this work, a new setup is explored, based on the lateral incidence of light on conventional planar waveguides such as glass slides or coverslips. Indium tin oxide was deposited onto both types of waveguides generating LMRs. The results of the simulations carried out agree well with the experimental results. As an example of the potential of this new and simple optical configuration, a humidity sensor with a sensitivity of 0.212 nm/% relative humidity (RH) in the range from 65% to 90% of RH was developed, which expedites the development of other types of sensors already explored with LMR-based optical fibre sensors.
Open Access
Multichannel refractometer based on lossy mode resonances
(IEEE, 2022) Fuentes Lorenzo, Omar; Corres Sanz, Jesús María; Domínguez Rodríguez, Ismel; Del Villar, Ignacio; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this work a new multiparameter sensor platform based on lossy mode resonances is presented. The structure consists of a soda-lime optical slab waveguide butt-coupled to multimode optical fibers. A variable thickness thin-film is deposited to generate multiple independent resonances on the same waveguide, which can be monitored using a single spectrometer. In order to show the potentiality of the structure, a broad resonance was selectively narrowed by etching sections of the LMR producer thin film. The spectral width is progressively reduced, allowing to selectively isolate independent resonances, which opens the path for multiple LMR generation in the same spectra in a multiparameter sensing platform. The experimental results were corroborated with a theoretical analysis based on the finite difference method (FDM). As a proof of concept, two refractometers on the same waveguide were fabricated and tested using PDMS cells. This platform can be easily miniaturized in order to integrate multiple sensors at low cost, what can be of interest for the development of multi-analyte biosensors probes. IEEE
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
Generation of lossy mode resonances in a broadband range with multilayer coated coverslips optimized for humidity sensing
(Elsevier, 2020) Bohórquez Navarro, Dina Luz; Del Villar, Ignacio; Corres Sanz, Jesús María; Matías Maestro, Ignacio; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Coverslips deposited with a metallic oxide can be employed for generating lossy mode resonances by lateral incidence of light on the coverslip. Here it is demonstrated that with copper oxide the fading observed with other materials in the near infrared (NIR) wavelength range is avoided and LMRs can be obtained in a broadband range from 400 to 1700 nm, which permitted to observe the better performance in the NIR region compared to the visible region: the sensitivity to humidity is improved by more than a factor of two. However, copper oxide is not adequate for sensing humidity. The sensitivity of the device was optimized initially with a tin oxide coating and later with an additional layer of agarose, specifically adequate for the detection of humidity. The best performance was obtained with an agarose concentration 1% w/v, which permitted to observe a 10-fold sensitivity increase compared to the same device without agarose. This opens the path towards the development of environmental, chemical or biological sensors with an optimized sensitivity to a specific parameter to detect.
Open Access
Fiber-optic lossy mode resonance sensors
(Elsevier, 2014) Arregui San Martín, Francisco Javier; Del Villar, Ignacio; Corres Sanz, Jesús María; Goicoechea Fernández, Javier; Ruiz Zamarreño, Carlos; Elosúa Aguado, César; Hernáez Sáenz de Zaitigui, Miguel; Rivero Fuente, Pedro J.; Socorro Leránoz, Abián Bentor; Urrutia Azcona, Aitor; Sánchez Zábal, Pedro; Zubiate Orzanco, Pablo; López Torres, Diego; Acha Morrás, Nerea de; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
In the last 4 years, experimental evidences about the potential use of optical sensors based on Lossy Mode Resonances (LMR) have been presented in the literature. These LMR sensors have some similarities with Surface Plasmon Resonance (SPR) sensors, the gold standard in label-free, real-time biomolecular interaction analysis. In these new LMR sensors, if the non-metallic nanocladding of an optical waveguide fulfills the conditions explained in this work, coupling of light to the cladding modes happens at certain resonance wavelengths, which enables the use of LMR devices as refractometers and opens the door to diverse applications such as in biology and proteomics research. These highly sensitive refractometers have already shown sensitivities higher than 20,000 nm/RIU or 5x10-7 RIU and, given the youth of this field, it is expected to achieve even better values.
Open Access
Tunable optical fiber pH sensors based on TE and TM Lossy Mode Resonances (LMRs)
(Elsevier, 2016) Zubiate Orzanco, Pablo; Ruiz Zamarreño, Carlos; Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, a high sensitivity optical fiber pH sensor based on lossy mode resonance (LMR) generated with transversal electric (TE) and transversal magnetic (TM) polarized light is presented. Poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) polymeric thin-films fabricated onto side-polished Dshaped optical fibers are used as pH-sensitive as well as LMR supporting coatings. The adequate selection of the pH-sensitive coating fabrication parameters enables to obtain devices working at different pH regions. Two devices have been obtained in order to measure pH from 4.0 to 5.0 and from 7.0 to 8.0 respectively. Obtained optical fiber pH sensors based on TE and TM LMRs showed a maximum sensitivity of 69 nm/pH, which means a resolution of ∼0.0008 pH units by using a conventional communications Optical Spectrum Analyzer (OSA) with 0.06 nm resolution.