Recherche

Llera Miguel

Adjoint-e scientifique HES

Compétences principales

Adjoint-e scientifique HES

Téléphone: +41 32 930 13 81

Haute Ecole Arc - Ingénierie
Espace de l'Europe 11, 2000 Neuchâtel, CH

Institut
Arc-Ingénierie

BSc HES-SO en Industrial Design Engineering - Haute Ecole Arc - Ingénierie

Métrologie
Microscopie

En cours

EFOCT Novel current measurement system for power applications based on fibre optics sensing

Rôle: Collaborateur/trice

Financement: Innosuisse

Description du projet :

A current measurement system is developed for applications in high-voltage power grid facilities.

Equipe de recherche au sein de la HES-SO: Llera Miguel

Partenaires académiques: EPFL

Partenaires professionnels: Condis SA

Durée du projet: 01.07.2021 - 30.05.2023

Montant global du projet: 1'500'368 CHF

Statut: En cours

Flexfiber

Rôle: Requérant(e) principal(e)

Financement: Innosuisse

Description du projet :

Flexfiber aims to develop highly flexible optical fibers for Human physiological parameters measurement in delicate organs. The fiber, 10-15 cm long, must be fully biocompatible and will have a strong impact on standalone implants monitoring and also on surgical tooling.

Equipe de recherche au sein de la HES-SO: Llera Miguel

Durée du projet: 01.11.2019 - 31.01.2021

Statut: En cours

Terminés

FLEXFIBER

Rôle: Requérant(e) principal(e)

Financement: Innosuisse

Description du projet :

Flexfiber vise à développer des fibres optiques hautement flexibles pour la mesure des paramètres physiologiques humains dans les organes délicats. La fibre, d'une longueur de 10 à 15 cm, doit être entièrement biocompatible et aura un fort impact sur le suivi des implants autonomes et également sur l'outillage chirurgical.

Equipe de recherche au sein de la HES-SO: Flahaut Frédéric, Llera Miguel

Durée du projet: 01.11.2019 - 31.01.2021

Statut: Terminé

ACCORD

Rôle: Requérant(e) principal(e)

Financement: IMEC, Belgique

Description du projet : Projet européen de type SSA (Specific Support Action). Le projet vise à mettre en place une plate-forme pour stimuler les collaborations universités-industrie au niveau européen dans le domaine de la photonique. Le but étant de stimuler l'intégration des étudiants de la photonique dans l'industrie européenne et de faire converger la recherche dans le domaine aux besoins réels de l'industrie européenne. EU N° 034041

Equipe de recherche au sein de la HES-SO: Banakh Oksana, Llera Miguel

Partenaires académiques: Metrologie Qualité; Llera Miguel, Metrologie Qualité

Durée du projet: 10.01.2007 - 22.06.2010

Statut: Terminé

Les fibres multimodes et leur limite pour une application LAN

Rôle: Collaborateur/trice

Financement: HES-SO Rectorat; ARC Ingénierie; ARC Ingénierie

Description du projet : L'augmentation du trafic de données dans les réseaux locaux (LAN) impose une augmentation de leur bande passante. La solution la plus viable à moyen terme d'un point de vue technique et économique se base sur la fibre optique. Deux types principaux de fibres optiques existent : La fibre monomode et la fibre multimode. La monomode présente une bande passante très élevée, mais, dû au faible diamètre de son c'ur, nécessite une connectique très précise et de ce fait présente un coût relativement élevé. La fibre multimode, par contre, ne nécessite pas de connectique précise et présente donc un coût moindre. Le problème actuel de cette dernière est que sa bande passante a été qualifiée pour des longues distances (~km) mais qu'elle n'est pas maîtrisée pour les distances courtes.

Equipe de recherche au sein de la HES-SO: Donzelot Christophe, Llera Miguel, Prieur Claudio

Durée du projet: 09.03.2004 - 22.04.2007

Montant global du projet: 138'078 CHF

Statut: Terminé

2021

Few-mode elastomeric optical fibers

Scientifique ArODES

Llera Miguel, Flahaut Frédéric, Bergerat Sylvain, Benoit Justin, Lüthi Rowan, Mathez Frédéric, Le Floch Sébastien, Salvadé Yves

Optical Materials Express, 2021, vol. 11, no. 7, pp. 2288-2299

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Résumé:

We present a new approach for producing elastomeric optical fibers with an optical behaviour corresponding to a few-mode optical fiber. Different fibers have been produced by first fabricating thermoplastic polyurethane preforms and subsequently drawing them. The fiber attenuation has been measured by the cut-back technique and the fiber bending transmission tolerance evaluated. The fiber potential has been assessed through two basic experiments in order to highlight the benefits of elasticity and a reduced core diameter. Future potential of the proposed fiber is discussed and shows a very auspicious path towards new and unexplored applications.

Few-mode elastomeric optical fibers

Scientifique

Miguel Llera

Optical Materials Express, 2021 , vol. 11, no 7, pp. 2288-2299

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Résumé:

2019

Fiber Bragg grating-based thermometer for drill bit temperature monitoring

Scientifique ArODES

Llera Miguel, Hey Tow Kenny, Bergerat Sylvain, Meyer Yves, Monnerat Serge, Gloriod Olivier, Le Floch Sébastien, Salvadé Yves, Thévenaz Luc

Applied Optics, 2019, vol. 58, no. 22, pp. 5924-5930

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Résumé:

The temperature measurement of a drill bit during an implantology drilling process is proposed by using a fiber Bragg grating fitted inside the drill bit. Due to the rotational nature of the drilling process, a free-space fiber-optic rotary joint is used for interrogating the fiber Bragg grating. Due to mechanical clearances and interferometric noise induced at this rotary joint, signal integrity is strongly deteriorated and is not workable without adequate measures. These measures involve a proper fiber lensing and a signal processing in order to remove the interferometric noise. Finally, a heating measurement on an implantology drill bit is performed and discussed for drilling several holes on a pork jaw sample.

2017

Cyclic coding for Brillouin optical time-domain analyzers using probe dithering

Scientifique ArODES

Iribas Haritz, Loayssa Alayn, Sauser Florian, Llera Miguel, Le Floch Sébastien

Optics Express, 2017, vol. 25, no. 8, pp. 8787-8800

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Résumé:

We study the performance limits of mono-color cyclic coding applied to Brillouin optical time-domain analysis (BOTDA) sensors that use probe wave dithering. BOTDA analyzers with dithering of the probe use a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This avoids non-local effects while keeping the Brillouin threshold at its highest level, thus preventing the spontaneous Brillouin scattering from generating noise in the deployed sensing fiber. In these conditions, it is possible to introduce an unprecedented high probe power into the sensing fiber, which leads to an enhancement of the signal-to-noise ratio (SNR) and consequently to a performance improvement of the analyzer. The addition of cyclic coding in these set-ups can further increase the SNR and accordingly enhance the performance. However, this unprecedented probe power levels that can be employed result in the appearance of detrimental effects in the measurement that had not previously been observed in other BOTDA set-ups. In this work, we analyze the distortion in the decoding process and the errors in the measurement that this distortion causes, due to three factors: the power difference of the successive pulses of a code sequence, the appearance of first-order non-local effects and the non-linear amplification of the probe wave that results when using mono-color cyclic coding of the pump pulses. We apply the results of this study to demonstrate the performance enhancement that can be achieved in a long-range dithered dual-probe BOTDA. A 164-km fiber-loop is measured with 1-m spatial resolution, obtaining 3-MHz Brillouin frequency shift measurement precision at the worst contrast location. To the best of our knowledge, this is the longest sensing distance achieved with a BOTDA sensor using mono-color cyclic coding.

2016

Interferometric measurements beyond the coherence length of the laser source

Scientifique

Yves Salvadé, Frank Przygodda, Marcel Rohner, Albert Polster, Yves Meyer, Serge Monnerat, Olivier Gloriod, Miguel Llera, Renaud Matthey, Joab Di Francesco, Florian Gruet, Gaetano Mileti

Optics Express, 2016 , vol. 24

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Liquid-air based Fabry-Pérot cavity on fiber tip sensor

Scientifique

Miguel Llera

Optics Express, 2016 , vol. Vol. 24, no Issue 8, pp. 8054-8065

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Résumé:

This paper presents a Fabry-Perot fiber tip sensor based on an air-liquid filled cavity. The cavity is sealed off by a thin gold coated membrane of parylene C, between 300 and 350 nm, creating a particularly flexible diaphragm. In order to retrieve and track the cavity of interest from other cavities formed within the sensor tip, a signal processing of the feedback signal is performed by inverse fast Fourier transform. The experimental sensor has been manufactured and tested for temperature, giving cavity length sensitivities of 6.1 nm/°C and 9.6 nm/°C for temperature increase and decrease respectively. The external gas pressure response gives a sensitivity of 15 nm/kPa. The fiber sensor has also been adapted for force sensing after silicone embedment and has shown a sensitivity of about 8.7 nm/mN. Finally, the sensor has been tested on insertion into a human temporal bone, proving that it could be an interesting candidate for insertion force monitoring for robotic cochlear implantation.

2017

NANOCI—Nanotechnology based cochlear implant with gapless interface to auditory neurons

Conference ArODES

Miguel Llera, Edith Laux

Otology & Neurotology ; Proceedings of the ACI Alliance 14th International Cochlear Implants on Children Conference, San Francisco, CA, USA

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Résumé:

Cochlear implants (CI) restore functional hearing in the majority of deaf patients. Despite the tremendous success of these devices, some limitations remain. The bottleneck for optimal electrical stimulation with CI is caused by the anatomical gap between the electrode array and the auditory neurons in the inner ear. As a consequence, current devices are limited through 1) low frequency resolution, hence sub-optimal sound quality and 2), large stimulation currents, hence high energy consumption (responsible for significant battery costs and for impeding the development of fully implantable systems). A recently completed, multinational and interdisciplinary project called NANOCI aimed at overcoming current limitations by creating a gapless interface between auditory nerve fibers and the cochlear implant electrode array. This ambitious goal was achieved in vivo by neurotrophin-induced attraction of neurites through an intracochlear gel-nanomatrix onto a modified nanoCI electrode array located in the scala tympani of deafened guinea pigs. Functionally, the gapless interface led to lower stimulation thresholds and a larger dynamic range in vivo, and to reduced stimulation energy requirement (up to fivefold) in an in vitro model using auditory neurons cultured on multi-electrode arrays. In conclusion, the NANOCI project yielded proof of concept that a gapless interface between auditory neurons and cochlear implant electrode arrays is feasible. These findings may be of relevance for the development of future CI systems with better sound quality and performance and lower energy consumption. The present overview/review paper summarizes the NANOCI project history and highlights achievements of the individual work packages.

Brillouin optical time-domain analyzer for extended sensing range using probe dithering and cyclic coding

Conference ArODES

Florian Sauser, Miguel Llera, Sébastien Le Floch

Proceedings of the 25th International Conference on Optical Fiber Sensors, 24-28 April 2017, Jeju, Korea, Republic of

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Résumé:

We present an enhanced performance Brillouin optical time-domain analysis sensor that uses dual probes waves with optical frequency modulation and cyclic coding. The frequency modulation serves to increase the probe power that can be injected in the fiber before the onset of non-local effects and noise generated by spontaneous Brillouin scattering. This leads to higher detected signal-to-noise ratio (SNR), which is further increased by the coding gain. The enhanced SNR translates to extended range for the sensor, with experiments demonstrating 1-m spatial resolution over a 164 km fiber loop with a 3-MHz Brillouin frequency shift measurement precision at the worst contrast position. In addition, we introduce a study of the power limits that can be injected in the fiber with cyclic coding before the appearance of distortions in the decoded signal.

Enhancement of signal-to-noise ratio in Brillouin optical time domain analyzers by dual-probe detection

Conference ArODES

Florian Sauser, Miguel Llera, Sébastien Le Floch

Proceedings of the 25th International Conference on Optical Fiber Sensors, 24-28 April 2017, Jeju, Korea, Republic of

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Résumé:

We demonstrate a simple technique to enhance the signal-to-noise ratio (SNR) in Brillouin optical time-domain analysis sensors by the addition of gain and loss processes. The technique is based on the shift of the pump pulse optical frequency in a double-sideband probe system, so that the gain and loss processes take place at different frequencies. In this manner, the loss and the gain do not cancel each other out, and it makes possible to take advantage of both informations at the same time, obtaining an improvement of 3 dB on the SNR. Furthermore, the technique does not need an optical filtering, so that larger improvement on SNR and a simplification of the setup are obtained. The method is experimentally demonstrated in a 101 km fiber spool, obtaining a measurement uncertainty of 2.6 MHz (2σ) at the worst-contrast position for 2 m spatial resolution. This leads, to the best of our knowledge, to the highest figure-of-merit in a BOTDA without using coding or raman amplification.

Réalisations

Recherche

Llera Miguel

Adjoint-e scientifique HES

Compétences principales

Optics

Fiber optics engineering

Microtechnique

Adjoint-e scientifique HES