• Negative refraction in a prism made of stacked subwavelength hole arrays 

      Navarro Cía, Miguel Upna; Beruete Díaz, Miguel Upna; Sorolla Ayza, Mario Upna; Campillo, Igor (Optical Society of America, 2008)   Artículo / Artikulua  OpenAccess
      Metamaterial structures are artificial materials that show unconventional electromagnetic properties such as negative refraction index, perfect lenses, and invisibility. However, losses are one of the big challenges to be ...
    • Negative refraction through an extraordinary transmission left-handed metamaterial slab 

      Beruete Díaz, Miguel Upna; Navarro Cía, Miguel Upna; Sorolla Ayza, Mario Upna; Campillo, Igor (American Physical Society, 2009)   Artículo / Artikulua  OpenAccess
      In this work we present numerical and experimental results of negative refraction through a negative index metamaterial based on miniaturized extraordinary transmission stacked subwavelength hole arrays, also known as ...
    • A new muscle architecture model with non-uniform distribution of muscle fiber types 

      Navallas Irujo, Javier Upna; Malanda Trigueros, Armando Upna; Gila Useros, Luis; Rodríguez Falces, Javier Upna; Rodríguez Carreño, Ignacio Upna (World Academy of Science, Engineering and Technology, 2007)   Artículo / Artikulua  OpenAccess
      According to previous studies, some muscles present a non-homogeneous spatial distribution of its muscle fiber types and motor unit types. However, available muscle models only deal with muscles with homogeneous ...
    • Nonbianisotropic complementary split ring resonators as angular selective metasurfaces 

      Rodríguez Ulibarri, Pablo Upna; Beruete Díaz, Miguel Upna (Optical Society of America, 2017)   Artículo / Artikulua  OpenAccess
      In this work, a metasurface with unconventional angular performance and composed by a nonbianisotropic complementary split ring resonator (NB-CSRR) is analyzed numerically and experimentally. A numerical study comparing ...
    • Nonlinear dynamics of vertical-cavity surface-emitting lasers 

      Panajotov, Krassimir; Sciamanna, Marc; Gatare, Ignace; Arizaleta Arteaga, Mikel; Thienpont, Hugo (Hindawi / Wiley, 2011)   Artículo / Artikulua  OpenAccess
      Nonlinear dynamics of Vertical-Cavity Surface-Emitting Lasers (VCSELs) induced by optical injection, optical feedback, current modulation and mutual coupling is reviewed. Due to the surface emission and cylindrical symmetry ...
    • Novel highly sensitive protein sensors based on tapered optical fibres modified with Au-based nanocoatings 

      Urrutia Azcona, Aitor Upna; Bojan, Kartheka; Marques, Leonel; Mullaney, Kevin; Goicoechea Fernández, Javier Upna; James, Stephen; Clark, Matt; Tatam, Ralph; Korposh, Sergiy (Hindawi Publishing Corporation, 2016)   Artículo / Artikulua  OpenAccess
      Novel protein sensors based on tapered optical fibres modified with Au coatings deposited using two different procedures are proposed. Au-based coatings are deposited onto a nonadiabatic tapered optical fibre using (i) a ...
    • On the performance of the zoned fishnet metamaterial lens with positive and negative reference phase 

      Pacheco Peña, Víctor Upna; Minin, Igor V.; Minin, Oleg V.; Beruete Díaz, Miguel Upna (IEEE, 2016)   Artículo / Artikulua  OpenAccess
      In this letter, several converging fishnet metalenses are designed using both the zoning and reference phase techniques. They are engineered with a focal length of 1.5λ0 at the design frequency of 55 GHz (λ0 = 5.45 mm) at ...
    • One-way quasiplanar terahertz absorbers using nonstructured polar dielectric layers 

      Rodríguez Ulibarri, Pablo Upna; Serebryannikov, Andriy E.; Beruete Díaz, Miguel Upna (American Physical Society, 2017)   Artículo / Artikulua  OpenAccess
      A concept of quasiplanar one-way transparent terahertz absorbers made of linear isotropic materials is presented. The resulting structure consists of a homogeneous absorbing layer of polar dielectric, GaAs, a dispersion-free ...
    • Optical fiber networks for remote fiber optic sensors 

      Fernández Vallejo, Montserrat Upna; López-Amo Sáinz, Manuel Upna (MDPI, 2012)   Artículo / Artikulua  OpenAccess
      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 ...
    • Optical fiber sensors based on nanoparticle-embedded coatings 

      Urrutia Azcona, Aitor Upna; Goicoechea Fernández, Javier Upna; Arregui San Martín, Francisco Javier Upna (Hindawi Publishing Corporation, 2015)   Artículo / Artikulua  OpenAccess
      The use of nanoparticles (NPs) in scientific applications has attracted the attention of many researchers in the last few years. The use of NPs can help researchers to tune the physical characteristics of the sensing coating ...
    • Optical fibre sensors using graphene-based materials: a review 

      Hernáez Sáenz de Zaitigui, Miguel Upna; Ruiz Zamarreño, Carlos Upna; Melendi Espina, Sonia; Bird, Liam; Mayes, Andrew; Arregui San Martín, Francisco Javier Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      Graphene and its derivatives have become the most explored materials since Novoselov and Geim (Nobel Prize winners for Physics in 2010) achieved its isolation in 2004. The exceptional properties of graphene have attracted ...
    • Optimization in nanocoated D-shaped optical fiber sensors 

      Del Villar, Ignacio Upna; Zubiate Orzanco, Pablo Upna; Ruiz Zamarreño, Carlos Upna; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna (Optical Society of America, 2017)   Artículo / Artikulua  OpenAccess
      Nanocoated D-shaped optical fibers have been proven as effective sensors. Here, we show that the full width at half minimum (FWHM) of lossy mode resonance can be reduced by optimizing the nanocoating width, thickness and ...
    • Optimization of a pin surface as a solution to suppress cavity modes in a packaged W-band microstrip receiver 

      Rebollo Mugueta, Ainara Upna; Gonzalo García, Ramón Upna; Ederra Urzainqui, Íñigo Upna (IEEE, 2014)   Artículo / Artikulua  OpenAccess
      A pin surface structure has been used in the upper metal plate of a packaged W-band RF front-end receiver in order to suppress the propagation of unwanted modes. A full parametric analysis of the periodic structure within ...
    • Optimization of sensitivity in long period fiber gratings with overlay deposition 

      Del Villar, Ignacio Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna; Lalanne, Philippe (Optical Society of America, 2005)   Artículo / Artikulua  OpenAccess
      The deposition of an overlay of higher refractive index than the cladding in a Long Period Fiber Grating (LPFG) permits to improve the sensitivity to ambient refractive index changes in a great manner. When the overlay is ...
    • Optimization of sensors based on multimode interference in single-mode–multimode– single-mode structure 

      Del Villar, Ignacio Upna; Socorro Leránoz, Abián Bentor Upna; Corres Sanz, Jesús María Upna; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna (IEEE, 2013)   Artículo / Artikulua  OpenAccess
      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 ...
    • An optimized method based on digitalized Lissajous curve to determine lifetime of luminescent materials on optical fiber sensors 

      Ridruejo Muro, Adrián; Acha Morrás, Nerea de Upna; Elosúa Aguado, César Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna (Hindawi Publishing Corporation, 2016)   Artículo / Artikulua  OpenAccess
      A method is proposed to determine lifetime of luminescent emissions based on the phase shift measurement employing the digitalized Lissajous representation: this diagram has been typically used with analogical algorithms, ...
    • Optimized strain long-period fiber grating (LPFG) sensors operating at the dispersion turning point 

      Del Villar, Ignacio Upna; Fuentes, Omar; Chiavaioli, Francesco; Corres Sanz, Jesús María Upna; Matías Maestro, Ignacio Upna (IEEE, 2018)   Artículo / Artikulua  OpenAccess
      Two phenomena for enhancing the sensitivity of longperiod fiber gratings are combined toward an increase of the sensitivity to strain of this type of devices: the dispersion turning point (DTP) and the cladding diameter ...
    • Optimizing interoperability between video-oculographic and electromyographic systems 

      Navallas Irujo, Javier Upna; Ariz Galilea, Mikel Upna; Villanueva Larre, Arantxa Upna; San Agustín, Javier; Cabeza Laguna, Rafael Upna (Rehabilitation Research & Development Service, 2011)   Artículo / Artikulua  OpenAccess
      A new system is presented that enhances the interoperability between a video-oculographic (VOG) system for mouse movement control and an electromyographic (EMG) system for mouse click detection. The proposed VOG-EMG system ...
    • Orthogonally polarized optical single sideband modulation for microwave photonics processing using stimulated Brillouin scattering 

      Sagüés García, Mikel Upna; Loayssa Lara, Alayn Upna (Optical Society of America, 2010)   Artículo / Artikulua  OpenAccess
      We present a novel technique to generate orthogonally polarized optical single sideband modulated signals. The modulation scheme is based on all optical stimulated Brillouin scattering processing of the optical carrier of ...
    • Overcoming non-local effects and Brillouin threshold limitations in Brillouin optical time domain sensors 

      Ruiz Lombera, Rubén; Urricelqui Polvorinos, Javier Upna; Sagüés García, Mikel Upna; Mirapeix, Jesús; López Higuera, José Miguel; Loayssa Lara, Alayn Upna (IEEE, 2015)   Artículo / Artikulua  OpenAccess
      We demonstrate, for the first time to our knowledge, a Brillouin optical time domain analysis (BOTDA) sensor that is able to operate with a probe power larger than the Brillouin threshold of the deployed sensing fiber ...