Now showing items 91-110 of 297

    • Experimental realization of an epsilon-near-zero graded-index metalens at terahertz frequencies 

      Pacheco Peña, Víctor Upna; Engheta, Nader; Kuznetsov, Sergei A.; Gentselev, Alexandr; Beruete Díaz, Miguel Upna (American Physical Society, 2017)   Artículo / Artikulua  OpenAccess
      The terahertz band has been historically hindered by the lack of efficient generators and detectors, but a series of recent breakthroughs have helped to effectively close the “terahertz gap.” A rapid development of terahertz ...
    • Experimental validation of a Ku-band dual circularly polarized metasurface antenna 

      Tellechea Pereda, Amagoia Upna; Caminita, Francesco; Martini, Enrica; Ederra Urzainqui, Íñigo Upna; Teniente Vallinas, Jorge Upna; Iriarte, Juan Carlos; Gonzalo García, Ramón Upna; Maci, Stefano (IEEE, 2018)   Artículo / Artikulua  OpenAccess
      The experimental validation of a Ku-band dual circularly polarized (CP) broadside-beam metasurface (MTS) antenna is presented. A radially modulated anisotropic single layer MTS has been synthesised employing sub-wavelength ...
    • Exploiting the dispersion of the double-negative-index fishnet metamaterial to create a broadband low-profile metallic lens 

      Orazbayev, Bakhtiyar Upna; Pacheco Peña, Víctor Upna; Beruete Díaz, Miguel Upna; Navarro Cía, Miguel Upna (Optical Society of America, 2015)   Artículo / Artikulua  OpenAccess
      Metamaterial lenses with close values of permittivity and permeability usually display low reflection losses at the expense of narrow single frequency operation. Here, a broadband low-profile lens is designed by exploiting ...
    • Extraordinary transmission and left-handed propagation in miniaturized stacks of doubly periodic subwavelength hole arrays 

      Beruete Díaz, Miguel Upna; Sorolla Ayza, Mario Upna; Navarro Cía, Miguel Upna; Falcone Lanas, Francisco Javier Upna; Campillo, Igor; Lomakin, Vitaliy (Optical Society of America, 2007)   Artículo / Artikulua  OpenAccess
      Metallic plates embedded between dielectric slabs and perforated by rectangular arrays of subwavelength holes with a dense periodicity in one of the directions support extraordinary transmission (ET) phenomena, viz. strong ...
    • Fabrication of Bragg gratings on the end facet of standard optical fibers by sputtering the same material 

      Ascorbe Muruzabal, Joaquín Upna; Corres Sanz, Jesús María Upna; Del Villar, Ignacio Upna; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna (IEEE, 2016)   Artículo / Artikulua  OpenAccess
      A sputtering process has been applied to deposit quarter-wavelength stacks on the end facet of cleaved optical fibers by using only one sputtering target. Standard multimode optical fibers were used as substrates to fabricate ...
    • Fe-rich ferromagnetic wires for self-sensing materials 

      Liberal Olleta, Íñigo Upna; Ederra Urzainqui, Íñigo Upna; Gonzalo García, Ramón Upna (IEEE, 2012)   Artículo / Artikulua  OpenAccess
      The possibility of using Fe-rich wires in mechanical stress self-sensing materials is investigated. To this end, a retrieval technique aimed to characterize the high-frequency magnetoimpedance effect in ferromagnetic wires ...
    • Fiber cavity ring down and gain amplification effect 

      Silva, Susana; Magalhães, Regina; Pérez Herrera, Rosa Ana Upna; López-Amo Sáinz, Manuel Upna; Marques, M. B.; Frazão, Orlando (Springer Nature, 2016)   Artículo / Artikulua  OpenAccess
      The effect of an erbium-doped fiber amplifier (EDFA) placed inside the fiber ring of a cavity ring down (CRD) configuration is studied. The limitations and advantages of this configuration are discussed, and the study of ...
    • A fiber optic ammonia sensor using a universal pH indicator 

      Rodríguez Rodríguez, Adolfo Josué; Ruiz Zamarreño, Carlos Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna; Cruz, René; May Arrioja, Daniel A. (MDPI, 2014)   Artículo / Artikulua  OpenAccess
      A universal pH indicator is used to fabricate a fiber optic ammonia sensor. The advantage of this pH indicator is that it exhibits sensitivity to ammonia over a broad wavelength range. This provides a differential response, ...
    • Fiber optic multiple-wavelength filter based on one dimensional photonic bandgap structures with defects 

      Del Villar, Ignacio Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna (IEEE, 2004)   Artículo / Artikulua  OpenAccess
      In this paper, a theoretical analysis is given of an optical fiber multiple-wavelength tunable filter based on a onedimensional (1-D) photonic bandgap (PBG) structure with four defects. To understand the positioning of ...
    • Fiber-optic nanorefractometer based on one-dimensional photonic-bandgap structures with two defects 

      Del Villar, Ignacio Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna (IEEE, 2004)   Artículo / Artikulua  OpenAccess
      A theoretical analysis of a fiber-optic photonic- bandgap (PBG)-based nanorefractometer is presented. Changes up to 11.2 dB in the optical output power in an index of refraction range of 1.7 with a sensitivity of 1.5 ...
    • Fisiopatología y técnicas de registro de los movimientos oculares 

      Gila Useros, Luis; Villanueva Larre, Arantxa Upna; Cabeza Laguna, Rafael Upna (Gobierno de Navarra, 2009)   Artículo / Artikulua  OpenAccess
      En el control de la motilidad ocular intervienen varios sistemas funcionales. Los reflejos vestíbulo-oculares y optocinéticos son respuestas automáticas para compensar los movimientos de la cabeza y del entorno visual y ...
    • Focus on terahertz plasmonics 

      Rahm, Marco; Nahata, Ajay; Akalin, Tahsin; Beruete Díaz, Miguel Upna; Sorolla Ayza, Mario Upna (IOP Publishing, 2015)   Artículo / Artikulua  OpenAccess
      Plasmonics is one of the growing fields in modern photonics that has garnered increasing interest over the last few years. In this focus issue, the specific challenges concerning terahertz plasmonics have been addressed ...
    • Frequency selective properties of coaxial transmission lines loaded with combined artificial inclusions 

      Falcone Lanas, Francisco Javier Upna; Gil Guruceaga, Javier (Hindawi, 2014)   Artículo / Artikulua  OpenAccess
      The properties of a modified coaxial transmission line by periodic inclusions will be discussed. The introduction of split ring resonators, conductor stubs, air gaps, and combination of these gives rise to new frequency ...
    • Frequency-based energy management strategy for stand-alone systems with distributed battery storage 

      Urtasun Erburu, Andoni Upna; Barrios Rípodas, Ernesto Upna; Sanchis Gúrpide, Pablo Upna; Marroyo Palomo, Luis Upna (IEEE, 2015)   Artículo / Artikulua  OpenAccess
      Distributed generation is an attractive solution for stand-alone AC supply systems. In such systems, the installation of two or more energy-storage units is recommended for system redundancy and may also be required when ...
    • Fringe generation with non-uniformly coated long-period fiber gratings 

      Del Villar, Ignacio Upna; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna; Cusano, Andrea; Paladino, Domenico; Cutolo, Antonello (Optical Society of America, 2007)   Artículo / Artikulua  OpenAccess
      In this work, the spectral characteristics of non-uniform symmetrically ring shaped coatings deposited on long-period fiber gratings (LPFGs) have been theoretically and experimentally investigated. To optimize the ...
    • Frozen mode from hybridized extraordinary transmission and Fabry-Perot resonances 

      Beruete Díaz, Miguel Upna; Rodríguez Ulibarri, Pablo Upna; Pacheco Peña, Víctor Upna; Navarro Cía, Miguel; Serebryannikov, Andriy E. (American Physical Society, 2013)   Artículo / Artikulua  OpenAccess
      Frozen modes arising in stacked subwavelength hole arrays are studied in detail. Their origin is proved to be connected with the interaction between the extraordinary transmission resonance and the Fabry–Perot cavity mode. ...
    • Full three-dimensional isotropic transformation media 

      García Meca, Carlos; Ortuño Molinero, Rubén Upna; Martí, J.; Martínez, Alejandro (IOP Publishing, 2014)   Artículo / Artikulua  OpenAccess
      We present a method that enables the implementation of full three-dimensional (3D) transformation media with minimized anisotropy. It is based on a special kind of shape-preserving mapping and a subsequent optimization ...
    • Gain dependence of the phase-shift spectra measured in coherent Brillouin optical time-domain analysis sensors 

      Mariñelarena Ollacarizqueta, Jon Upna; Urricelqui Polvorinos, Javier Upna; Loayssa Lara, Alayn Upna (IEEE, 2016)   Artículo / Artikulua  OpenAccess
      We report on the effects of large pump pulse powers on Brillouin optical time-domain analysis (BOTDA) sensors based on phase-modulated probe wave and coherent self-heterodyne detection. These sensors are particularly ...
    • Gain improvement of dual band antenna based on complementary rectangular split-ring resonator 

      Ortiz Pérez de Eulate, Noelia Upna; Falcone Lanas, Francisco Javier Upna; Sorolla Ayza, Mario Upna (Hindawi / Wiley, 2012)   Artículo / Artikulua  OpenAccess
      A simple and successful dual band patch linear polarized rectangular antenna design is presented. The dual band antenna is designed etching a complementary rectangular split-ring resonator in the patch of a conventional ...
    • Gasohol quality control for real time applications by means of a multimode interference fiber sensor 

      Rodríguez Rodríguez, Adolfo Josué; Baldovino Pantaleón, Óscar; Cruz, René; Ruiz Zamarreño, Carlos Upna; Matías Maestro, Ignacio Upna; May Arrioja, Daniel A. (MDPI, 2014)   Artículo / Artikulua  OpenAccess
      In this work we demonstrate efficient quality control of a variety of gasoline and ethanol (gasohol) blends using a multimode interference (MMI) fiber sensor. The operational principle relies on the fact that the addition ...