Publications
369 results found
Pacheco-Peña V, Beruete M, Fernández-Domínguez AI, et al., 2015, Localized emitters close to nano-bowties: insight via conformal transformation, Metamaterials’2015, Publisher: IEEE
Investigating the near-field interaction of a dipole source such as a single quantum-dot with nearby dimers such as bowties is a challenging problem because of the lack of analytical models and the difficulty to perform the experiment. We tackle this problem here by using a conformal transformation. We show how, in the electrostatic approximation, the bowtie and point dipole source can be transformed into the analytically solvable configuration of a periodic metal-insulator-metal and point dipole source configuration. The analytical solutions are validated with full-wave simulations.
Khromova I, Mitrofanov O, Navarro-Cia M, et al., 2015, Resonant terahertz absorption in carbon microfibres, Metamaterials’2015, Publisher: IEEE, Pages: 433-435
Microsized carbon fibres exhibit strong resonant absorption at terahertz fre-quencies. Using near-field terahertz time-domain spectroscopy, we probe their conductivity byanalysing the degree of field enhancement produced by plasmonic resonances. We demonstrate,theoretically and experimentally, the potential usability of carbon microfibres as terahertz ab-sorbers with engineerable response.
Orazbayev B, Pacheco-Peña V, Beruete M, et al., 2015, A self-supporting broadband zoned fishnet metamaterial lens operaring at the millimetre-wave V-band, Metamaterials’2015, Publisher: IEEE, Pages: 241-243
By combining the zoning technique with the strong dispersion of the fishnet metamaterial, a broadband fishnet diffractive optical element is designed, fabricated and measured at millimeter-waves. Diffraction-limited full width at half maximum ~0.8λ0 is demonstrated experimentally when the focal properties of the lens are studied. Also, directivity of ~16.6 dBi is achieved when the fishnet lens is used in a lens antenna configuration together with an open-ended waveguide operating as a feeder.
Navarro-Cia M, Mesa F, Torres V, et al., 2015, Analytical approach for Fishnet Structures: A Systematic Circuit Approach, Metamaterials'2015, Publisher: IEEE, Pages: 916-918
Fishnet structures provide a popular procedure to obtain negative-refractionindexartificial media. They are basically stacked extraordinary-transmission structures that areclosely spaced. Thus these structures can be built by combining two or more metallic plates witha 2D periodic distribution of small apertures. Analytical models based on equivalent circuits arealmost trivially obtained when the electric separation between metal plates is relatively large.However the more interesting situation arising from tightly coupled screens is more involvedand only heuristic equivalent-circuit approaches have been reported in the literature. In thiscontribution a systematic approach to obtain a general circuit model for this kind of structuresis developed.
Torres V, Pacheco-Peña V, Orazbayev B, et al., 2015, Epsilon-Near-Zero Lens for Beamshaping of Sub-Terahertz Waves, 40th International Conference on Infrared, Millimeter, and Terahertz Waves 2015, IRMMW-THz 2015, Publisher: IEEE
The focal properties and radiation characteristics ofan epsilon-near-zero metamaterial lens are investigatednumerically and experimentally in the D-band. The experimentalfocusing enhancement of the lens is ~16 dB. The directivity of thelens antenna configuration at 144 GHz is ~18 dBi and thecorresponding gain scan loss below 3 dB is achieved for angles upto ±15 deg.
Orazbayev B, Pacheco-Peña V, Torres V, et al., 2015, Zoning technique for a Broadband Fishnet Metamaterial Lens, 40th International Conference on Infrared, Millimeter, and Terahertz Waves 2015, IRMMW-THz 2015, Publisher: IEEE
Pacheco-Peña V, Beruete M, Fernández-Domínguez AI, et al., 2015, Conformal transformation for nanoantennas, 6th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META’15, Pages: 894-895
Modeling the response of nanoantennas excited by a localized emitter is extremely computational intensive. Transformation optics can ease this task. Here we show the conformal transformation required to model a plasmonic bow-tie as a parallel-plate plasmonic waveguide. The eigenmodes of a parallel-plate plasmonic waveguide can be calculated analytically, enabling the calculation of the eigenmodes and the absorption cross section of the original bow-tie via thetransformation. Full-wave simulations corroborate the approach.
Aouani H, Navarro-Cía M, Rahmani M, et al., 2015, Corrections to Unveiling the Origin of Third Harmonic Generation in Hybrid ITO-Plasmonic Crystals [Adv. Optical Mater., 3, 8, (2015) 1059-1065], DOI: 10.1002/adom.201500112, Advanced Optical Materials, Vol: 3, Pages: 986-986
- Cite
- Citations: 1
Rodríguez-Ulibarri P, Pacheco-Peña V, Falcone F, et al., 2015, Experimental Demonstration of Deflection Angle Tuning inDiffraction-Inspired Unidirectional Structures, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI)
Orazbayev B, Pacheco-Peña V, Beruete M, et al., 2015, A Broadband Zoned Fishnet Metamaterial Lens, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI), Publisher: IEEE
Osuna D, Beruete M, Teniente J, et al., 2015, High-gain and Low-profile Metalens-horn Antenna based on the FishnetMetamaterial, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI)
Lenses are commonly used to reduce the profile and enhance radiation propertiesof horn antennas. To this purpose, metallic as well as metamaterial lenses havebeen successfully employed in the past showing a clear gain enhancement andshortening of the horn antenna (D. Ramaccia, et al., IEEE Trans. AntennasPropag., 61, 2929-2937, 2013). The aim of this work is to implement a highfrequencymetamaterial lens-antenna based on a fishnet structure which promisesimproved impedance matching compared to dielectric lenses.Here, we show a metamaterial fishnet lens-antenna that enhances the antenna gainwhen it is coupled to the aperture of a modified H-plane sectorial horn showingalso good matching in a narrow bandwidth. The fishnet consists in a pair ofperforated metallic 0.089λ0-thick plates separated by a gap of 0.133λ0. The unitcell of each perforated plate is 0.535λ0 × 0.892λ0 and is perforated with a circularaperture of diameter 0.446λ0. The fishnet matches the aperture of the H-planesectorial horn dimensions which are 5.89λ0 wide and 0.892λ0 high. Hence, itconsists of a row of 11 unit cells, see Figure. The antenna is designed to work at53.5 GHz. For given aperture dimensions a wide flare angle such as the oneemployed here means a low profile horn antenna (i.e. a shorter horn length). Thesemi-angle flare of the horn is 75º and this implies a horn length of 1.31λ0. Thesystem was simulated using the commercial software CST MWSTM. Results showgood matching at 53.5 GHz, and a realized gain enhancement within a 1 GHzbandwidth, with a gain peak of 15.8 dB at 53.5 GHz (see Figure). A standard Hplanesectorial horn with a 5.16λ0 long and 30º semi-angle flare provides the samegain, which means that our design is about 74% shorter although it works in anarrower bandwidth. Gain is enhanced at the expense of bandwidth. Nevertheless,results show another range between 58 GHz and 60 GHz where gain is alsoenhanc
Beaskoetxea U, Beruete M, Falcone F, et al., 2015, High Gain Leaky Wave AntennaOperating at 0.566 THz, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI), Publisher: IEEE
Navarro-Cia M, Melzer JE, Harrington JA, et al., 2015, Effective Single HE₁₁ Mode Propagation in Silver-coated Teflon Tubes for THz applications, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI), Publisher: IEEE
Torres V, Pacheco-Peña V, Orazbayev B, et al., 2015, 144 GHz Epsilon-near-zero Lens Antenna, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI), Publisher: IEEE
Metamaterials have revolutionized the design of lenses. Free-space matching has been traditionally achieved by thick anti-reflective coatings. However, at millimeter-waves, simple anti-reflective coatings remain elusive. In this range, the impedance matching attainable with metamaterials can be a viable solution. This holds promise for enhancing the gain of highly directive lens antennas.
Kuznetsov SA, Astafev MA, Beruete M, et al., 2015, 350 GHz Holographic Surface for Single- and Multi-focusing, IEEE AP-S International Symposium on Antennas and Propagation 2015 and USNC/URSI National Radio Science Meeting 2015 (2015 IEEE AP-S/URSI), Publisher: IEEE
Reflectors are the preferred high-gain antenna for ground base stations and radar applications. However, they are bulky and heavy for airborne applications. Hence, planar arrays such as microstrip antenna arrays are favored in airborne use. Unfortunately, losses in the array feeding network are unacceptable at Terahertz (THz) frequencies due to the significant absorption of any material/substrate in this range (D. Grischkowsky et al., J. Opt. Soc. Am. B, 7, 2006, 1990). Therefore, high-gain reflectarrays are the preferred practical solution for high data rate THz airborne applications.
Pacheco-Peña V, Beruete M, Navarro-Cia M, et al., 2015, High Resolution Terajets Using 3D Dielectric Cuboids, 2015 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, Publisher: IEEE
The limit imposed intrinsically by the diffraction of electromagnetic waves has been extensively studied with the aim to improve the performance of microscopy techniques and to obtain subwavelength resolution. Several techniques have been proposed to solve this disadvantage such as metamaterials and microspherical particles, to name a few.
Khromova I, Navarro-Cia M, Brener I, et al., 2015, Dipolar resonances in conductive carbon micro-fibers probed by near-field terahertz spectroscopy, APPLIED PHYSICS LETTERS, Vol: 107, ISSN: 0003-6951
- Author Web Link
- Open Access Link
- Cite
- Citations: 18
Khromova I, Navarro-Cia M, Brener I, et al., 2015, Probing terahertz conductivity of individual conductive dipoles via near-field terahertz spectroscopy, Workshop on THz - Saint Petersburg 2015
Nearfield terahertz spectroscopy can be used to probe the terahertz conductivity of individual resonant particles. We applied this technique to individual microsized carbon fibres and observed strong plasmonic resonances in the terahertz range. Analysing the resonance frequency of the samples and the degree of field enhancement induced by the incident terahertz pulse, we estimated their terahertz conductivity (1-5.10⁴ S/m). This method can be useful for characterising semimetallic and semiconductor terahertz absorbers, microantennas and metamaterial elements.
Pacheco-Pena V, Navarro-Cia M, Orazbayev B, et al., 2015, Zoned Fishnet Lens Antenna With Reference Phase for Side-Lobe Reduction, IEEE Transactions on Antennas and Propagation, Vol: 63, Pages: 3710-3714, ISSN: 1558-2221
Reduction of first side-lobe level (SLL) and nulls in artificial fishnet metalenses is accomplished here by applying the reference phase concept along with the zoning technique. Higher focusing efficiency is achieved for a specific reference phase when comparing numerically and experimentally four different designs. For such best design, an improvement of the first SLL (~2.4 dB), first null (~13 dB), and gain (~1.77 dB) is achieved experimentally compared to the design without reference phase.
Orazbayev B, Beruete M, Pacheco-Pena V, et al., 2015, Soret Fishnet Metalens Antenna (vol 5, 9988, 2015), SCIENTIFIC REPORTS, Vol: 5, ISSN: 2045-2322
Orazbayev B, Beruete M, Pacheco-Peña V, et al., 2015, Soret fishnet metalens antenna., Scientific Reports, Vol: 4, ISSN: 2045-2322
At the expense of frequency narrowing, binary amplitude-only diffractive optical elements emulate refractive lenses without the need of large profiles. Unfortunately, they also present larger Fresnel reflection loss than conventional lenses. This is usually tackled by implementing unattractive cumbersome designs. Here we demonstrate that simplicity is not at odds with performance and we show how the fishnet metamaterial can improve the radiation pattern of a Soret lens. The building block of this advanced Soret lens is the fishnet metamaterial operating in the near-zero refractive index regime with one of the edge layers designed with alternating opaque and transparent concentric rings made of subwavelength holes. The hybrid Soret fishnet metalens retains all the merits of classical Soret lenses such as low profile, low cost and ease of manufacturing. It is designed for the W-band of the millimeter-waves range with a subwavelength focal length FL = 1.58 mm (0.5λ0) aiming at a compact antenna or radar systems. The focal properties of the lens along with its radiation characteristics in a lens antenna configuration have been studied numerically and confirmed experimentally, showing a gain improvement of ~2 dB with respect to a fishnet Soret lens without the fishnet metamaterial.
Navarro-Cía M, Melzer JE, Harrington JA, et al., 2015, Silver-Coated Teflon Tubes for Waveguiding at 1–2 THz, Journal of Infrared, Millimeter, and Terahertz Waves, Vol: 36, Pages: 542-555, ISSN: 1866-6892
Orazbayev B, Pacheco-Pena V, Beruete M, et al., 2015, Exploiting the dispersion of the double-negative-index fishnet metamaterial to create a broadband low-profile metallic lens, Optics Express, Vol: 23, Pages: 8555-8564, ISSN: 1094-4087
Rodriguez-Ulibarri P, Pacheco-Pena V, Navarro-Cia M, et al., 2015, Experimental demonstration of deflection angle tuning in unidirectional fishnet metamaterials at millimeter-waves, Applied Physics Letters, Vol: 106, ISSN: 1077-3118
Kuznetsov SA, Astafev MA, Beruete M, et al., 2015, Planar Holographic Metasurfaces for Terahertz Focusing, SCIENTIFIC REPORTS, Vol: 5, ISSN: 2045-2322
- Author Web Link
- Open Access Link
- Cite
- Citations: 64
Torres V, Orazbayev B, Pacheco-Pena V, et al., 2015, Experimental Demonstration of a Millimeter-Wave Metallic ENZ Lens Based on the Energy Squeezing Principle, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, Vol: 63, Pages: 231-239, ISSN: 0018-926X
- Author Web Link
- Open Access Link
- Cite
- Citations: 43
Orazbayev B, Pacheco-Pena V, Torres V, et al., 2015, Zoned fishnet metamaterial lens with millimetre-wave dual-band response, 9th European Conference on Antennas and Propagation EuCAP, Publisher: IEEE
Beaskoetxea U, Pacheco-Pena V, Orazbayev B, et al., 2015, High Gain Flat Sinusoidal Bull's Eye Leaky Millimetre-Wave Antenna, 9th European Conference on Antennas and Propagation EuCAP, Publisher: IEEE
Torres V, Sanchez N, Etayo D, et al., 2015, Compact Quarter-Wave Plate Metasurface at 1 and 2.2 THz, 9th European Conference on Antennas and Propagation EuCAP, Publisher: IEEE
Torres V, Orazbayev B, Pacheco-Pena V, et al., 2015, 144 GHz Epsilon-Near-Zero Metamaterial Lens, 9th European Conference on Antennas and Propagation EuCAP, Publisher: IEEE
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.