Fernández Vallejo, Montserrat

person.page.identifierURI

https://academica-e.unavarra.es/handle/2454/49024

Last Name

Fernández Vallejo

First Name

Montserrat

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Ingeniería Eléctrica y Electrónica

person.page.observainves

750618

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8522

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Now showing 1 - 10 of 19

Open Access
Comparative study of ring and random cavities for fiber lasers
(Optical Society of America, 2014) Fernández Vallejo, Montserrat; Rota Rodrigo, Sergio; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
An experimental comparison of three fiber laser structures with the same Raman gain medium is presented in order to establish the main pros and cons of each basic scheme. The first fiber laser is based on a hybrid ring–random fiber laser, the second one is a pure ring fiber laser, and the last one is a random fiber laser. Several aspects have been taken into account in the study. First, from the optical point of view, the parameters of interest compared are output power, lasing threshold, slope efficiency, power fluctuations, and the longitudinal modes have been analyzed. Second, the possible utilization of fiber lasers in digital modulated optical communication systems is also studied.
Open Access
Stabilization of dual-wavelength erbium doped ring fiber lasers by single-mode operation
(IEEE, 2010) Quintela, M. A.; Pérez Herrera, Rosa Ana; Canales, Irene; Fernández Vallejo, Montserrat; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a novel single-longitudinal-mode (SLM) dual-wavelength laser configuration is proposed and demonstrated. This laser is based on ring resonators, and employs fiber Bragg gratings to select the operation wavelengths. It includes a short piece of highly doped Er-fiber that acts as the active medium. The stable SLM operation is guaranteed when the two lasing channels present similar output powers. This behavior is shown for different pump powers.
Open Access
L-band multiwavelength single-longitudinal mode fiber laser for sensing applications
(IEEE / OSA, 2012) Pérez Herrera, Rosa Ana; Ullán Nieto, Ángel; Leandro González, Daniel; Fernández Vallejo, Montserrat; Quintela, M. A.; Loayssa Lara, Alayn; López Higuera, José Miguel; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a novel single-longitudinal-mode (SLM) four-wavelength laser configuration for sensing applications in the L-band is proposed and experimentally demonstrated. The sensor system presented here is based on ring resonators, and employs fiber Bragg gratings to select the operation wavelengths. The stable SLM operation is guaranteed when all the lasing channels present similar output powers. It is also experimentally demonstrated that when a SLMbehavior is achieved, lower output power fluctuations are obtained. Characterization of the lasing structure for temperature sensing is also shown.
Open Access
Optical fiber networks for remote fiber optic sensors
(MDPI, 2012) Fernández Vallejo, Montserrat; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This paper presents an overview of optical fiber sensor networks for remote sensing. Firstly, the state of the art of remote fiber sensor systems has been considered. We have summarized the great evolution of these systems in recent years; this progress confirms that fiber-optic remote sensing is a promising technology with a wide field of practical applications. Afterwards, the most representative remote fiber-optic sensor systems are briefly explained, discussing their schemes, challenges, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered.
Open Access
Internal modulation of a Random fiber laser
(Optical Society of America, 2013) Bravo Acha, Mikel; Fernández Vallejo, Montserrat; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A characterization of a modulated random mirror laser has been experimentally carried out. Unlike conventional internally modulated fiber lasers, no distortion of the modulating frequency or self-mode-locking effects were measured. The behavior of the laser using pulsed and analog modulation up to 12 GHz is shown.
Restricted
Desarrollo de estructuras basadas en redes de disfracción de fibra óptica para sensores y láseres
(2008) Fernández Vallejo, Montserrat; López-Amo Sáinz, Manuel; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa
Open Access
Random fiber lasers: application to fiber optic sensors networks
(IEEE, 2017) López-Amo Sáinz, Manuel; Leandro González, Daniel; Miguel Soto, Verónica de; Bravo Acha, Mikel; Fernández Vallejo, Montserrat; Pérez Herrera, Rosa Ana; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
Recently, random mirrors have been proposed as a method to create fiber laser cavities. This kind of cavity is based on cooperative Rayleigh scattering, which is generated along a fiber due to the material inhomogeneities presented in that fiber. In this work, basics of Random fiber lasers and different demonstrated lasing sensors systems for interrogating arrays of optical fiber sensors are shown. These systems use different kinds of amplification and cavities schemes and can interrogate optical fiber sensors located up to 225 km away.
Open Access
46-km-long Raman amplified hybrid double-bus network with point and distributed Brillouin sensors
(IEEE, 2012) Fernández Vallejo, Montserrat; Olier Aguado, David; Zornoza Indart, Ander; Pérez Herrera, Rosa Ana; Díaz Lucas, Silvia; Elosúa Aguado, César; Bariáin Aisa, Cándido; Loayssa Lara, Alayn; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We experimentally demonstrate a 46-km hybrid network that combine point and distributed Brillouin sensors. The proposed sensor network multiplexes low-cost intensity point sensors based on fiber-optic tapers, which are able to measure vibrations in the 0.01 to 50 Hz frequency range. The sensor network with a double-bus is a low noise configuration, which offers a higher optical signal to noise ratio and dynamic range than a single-bus. Thus, the number of sensors to be multiplexed could increase or we could reach further distances. The system also deploys remote distributed Raman amplification to extend the sensing range.
Open Access
Robust fiber-optic sensor networks
(Springer, 2012) Pérez Herrera, Rosa Ana; Fernández Vallejo, Montserrat; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The ability to operate despite failure will become increasingly important as the use of optical sensor networks grows, and the amount of sensing information to be handled by a sensor network is increasing, especially for safety and security applications. In this review, the four categories of protection to allow service to be reestablished after a failure (dedicated/shared and line/path) are thoroughly discussed. This paper also presents an overview of the most representative robust fiber-optic sensor systems, discussing their schemes, pros and cons.
Open Access
Advanced graphene-based transparent conductive electrodes for photovoltaic applications
(MDPI, 2019) Fernández, Susana; Boscá, Alberto; Pedrós, Jorge; Inés Ortigosa, Andrea; Fernández Vallejo, Montserrat; Arnedo Gil, Israel; González, José Pablo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
New architectures of transparent conductive electrodes (TCEs) incorporating graphene monolayers in different configurations have been explored with the aim to improve the performance of silicon-heterojunction (SHJ) cell front transparent contacts. In SHJ technology, front electrodes play an important additional role as anti-reflectance (AR) coatings. In this work, different transparent-conductive-oxide (TCO) thin films have been combined with graphene monolayers in different configurations, yielding advanced transparent electrodes specifically designed to minimize surface reflection over a wide range of wavelengths and angles of incidence and to improve electrical performance. A preliminary analysis reveals a strong dependence of the optoelectronic properties of the TCEs on (i) the order in which the different thin films are deposited or the graphene is transferred and (ii) the specific TCO material used. The results shows a clear electrical improvement when three graphene monolayers are placed on top on 80-nm-thick ITO thin film. This optimum TCE presents sheet resistances as low as 55 Ω/sq and an average conductance as high as 13.12 mS. In addition, the spectral reflectance of this TCE also shows an important reduction in its weighted reflectance value of 2-3%. Hence, the work undergone so far clearly suggests the possibility to noticeably improve transparent electrodes with this approach and therefore to further enhance silicon-heterojunction cell performance. These results achieved so far clearly open the possibility to noticeably improve TCEs and therefore to further enhance SHJ contact-technology performance.