Person: Rodríguez Ulibarri, Pablo
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Rodríguez Ulibarri
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Pablo
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0000-0001-5705-5457
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Publication Open Access Low profile THz periodic leaky-wave antenna(IEEE, 2014) Beaskoetxea Gartzia, Unai; Beruete Díaz, Miguel; Rodríguez Ulibarri, Pablo; Etayo Salinas, David; Sorolla Ayza, Mario; Navarro Cía, Miguel; Zehar, Mokhtar; Blary, Karine; Chahadih, Abdallah; Han, Xiang-Lei; Akalin, Tahsin; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaIn this work, a 0.566THz flat leaky-wave antenna, consisting of a central λ0/2 slot surrounded by straight parallel wedge corrugations, is numerically and experimentally analyzed. Simulations show a moderately high gain and no significant differences when compared with a typical square corrugation profile. Numerical comparison is also made for the designed and manufactured antennas. High transmission enhancement in the corrugated case is obtained, compared to that given by a single central slot with no grooves. This kind of antennas finds several applications in different frequency ranges, including the nowadays high-interest range of the THz.Publication Open Access Annular apertures in metallic screens as extraordinary transmission and frequency selective surface structures(IEEE, 2017) Rodríguez Ulibarri, Pablo; Navarro Cía, Miguel; Rodríguez Berral, Raúl; Mesa, Francisco; Medina, Francisco; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaA 2-D periodic array of annular apertures (or ring slots) is studied using an accurate circuit model. The model accounts for distributed and dynamic effects associated with the excitation of high-order modes operating above or below cutoff but not far from their cutoff frequencies. This paper allows to ascertain the substantial differences of the underlying physics when this structure operates as a classical frequency selective surface or in the extraordinary-transmission (ET) regime. A discussion of two different designs working at each regime is provided by means of the equivalent circuit approach (ECA), full wave simulation results, and experimental characterization. The agreement between the equivalent circuit calculation applied here and the simulation and experimental results is very good in all the considered cases. This validates the ECA as an efficient minimal-order model and a low computational-cost design tool for frequency selective surfaces and ET-based devices. Additional scenarios such as oblique incidence and parametric studies of the structural geometry are also considered.Publication Open Access Terahertz epsilon-near-zero graded-index lens(Optical Society of America, 2013) Torres Landívar, Víctor; Pacheco-Peña, Víctor; Rodríguez Ulibarri, Pablo; Navarro Cía, Miguel; Beruete Díaz, Miguel; Sorolla Ayza, Mario; Engheta, Nader; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua, 055/01/11An epsilon-near-zero graded-index converging lens with planar faces is proposed and analyzed. Each perfectly-electric conducting (PEC) waveguide comprising the lens operates slightly above its cut-off frequency and has the same length but different cross-sectional dimensions. This allows controlling individually the propagation constant and the normalized characteristic impedance of each waveguide for the desired phase front at the lens output while Fresnel reflection losses are minimized. A complete theoretical analysis based on the waveguide theory and Fermat’s principle is provided. This is complemented with numerical simulation results of two-dimensional and three-dimensional lenses, made of PEC and aluminum, respectively, and working in the terahertz regime, which show good agreement with the analytical work.Publication Open Access Hedgehog subwavelength hole arrays: control over the THz enhanced transmission(Institute of Physics Publishing, 2013) Navarro Cía, Miguel; Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua: 055/01/11By backing or sandwiching a holey metal layer with or between isotropic dielectric slabs, additional peaks of transmission within the long-wavelength regime arise as a result of the induced transverse magnetic (TM) or transverse electric (TE) grounded dielectric modes. A similar control of the complex surface wave modes, and thus of the extraordinary transmission (ET) peaks, is demonstrated here via anisotropic slabs in the form of a fakir's bed of nails. However, it is shown that those ET peaks formed from TE modes are suppressed because of the inherent dispersion characteristics of the free-standing grounded pins. This allows the red-shifting of the ET for the polarization parallel to the larger in-plane period of the hole array, but unlike the dielectric isotropic slab configuration, the orthogonal polarization remains inhibited.Publication Open Access Frozen mode from hybridized extraordinary transmission and Fabry-Perot resonances(American Physical Society, 2013) Beruete Díaz, Miguel; Rodríguez Ulibarri, Pablo; Pacheco-Peña, Víctor; Navarro Cía, Miguel; Serebryannikov, Andriy E.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua, “Formación de Tecnólogos” 055/01/11. M.N.CFrozen 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. The analysis is done for various situations that differ in metal plate thicknesses and sizes and shape of the holes. Dispersion results and finite-stack transmission spectra are in good agreement, both showing the features indicating hybridization. The boundaries of the hybridization are found in terms of the geometrical parameters. The effect of the number of stacked plates on the transmission has been demonstrated. Finally, it is shown that the group index of refraction ng in the considered finite structures can be larger than 200. The obtained estimates of ng, which are based on dispersion and transmission results, well coincide with each other.Publication Open Access Wideband unidirectional transmission with tunable sign-switchable refraction and deflection in nonsymmetric structures(American Physical Society, 2013) Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Navarro Cía, Miguel; Serebryannikov, Andriy E.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua, “Formación de Tecnólogos” 055/01/11. M.N.CA general theory of reciprocal unidirectional transmission with tunable sign-switchable refraction and deflection of outgoing wave in structures with broken spatial inversion symmetry is presented. Several coupling scenarios connected with the diffraction-inspired asymmetry in transmission are considered for volumetric structures with one-side corrugations. They illustrate conditions of coexistence of diodelike unidirectional transmission and tunability of deflection and refraction, including change of their sign. Simulation results are presented and analyzed for nonsymmetric structures based on the stacked subwavelength hole array metamaterial. It is shown that one-way coupling can appear within a wide range of frequencies and angles of incidence, a part of which may be used to obtain different signs of deflection. Transmission results and field distributions confirm the possibility of obtaining high-contrast unidirectional transmission that can be tuned by varying incidence angle, while frequency is fixed. A pronounced unidirectional transmission is demonstrated at negative deflection in structures that are only 0.47λ0 thick, whereas a thicker structure is required in order to obtain both signs of deflection in a unidirectional regime.Publication Open Access Mid-infrared plasmonic inductors: enhancing inductance with meandering lines(Nature Publishing Group, 2014) Torres Landívar, Víctor; Ortuño Molinero, Rubén; Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Sorolla Ayza, Mario; Griol, Amadeu; Martínez, Alejandro; Navarro Cía, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua: 055/01/11; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaWe present a mid-infrared inductor that when applied to an extraordinary transmission hole array produces a strong redshift of the resonant peak accompanied by an unprecedented enlargement of the operation bandwidth. The importance of the result is twofold: from a fundamental viewpoint, the direct applicability of equivalent circuit concepts borrowed from microwaves is demonstrated, in frequencies as high as 17â€...THz upholding unification of plasmonics and microwave concepts and allowing for a simplification of structure design and analysis; in practical terms, a broadband funnelling ofinfrared radiation with fractional bandwidth and efficiency as high as 97% and 48%, respectively, is achieved through an area less than one hundredth the squared wavelength, which leads to an impressive accessible strong field localization that may be of great interest in sensing applications.