Open Access
Compact dual-band terahertz quarter-wave plate metasurface
(IEEE, 2014) Torres Landívar, Víctor; Etayo Salinas, David; Ortuño Molinero, Rubén; Navarro Cía, Miguel; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A dual-band quarter-wave plate based on a modified extraordinary transmission hole array is numerically analyzed and experimentally demonstrated at terahertz frequencies. To control independently orthogonal polarizations, the original square holes are connected with vertical slits and their lateral straight sides are replaced by meander lines. This smart design enables dual-band operation with unprecedented fractional bandwidths in a compact structure. Considering a flattening deviation lower than 40% of the optimum value, a fractional bandwidth of 53.8% and 3.8% is theoretically obtained (16.8% and 2.9% in the experiment) at 1 and 2.2 THz, respectively. At these two frequencies, the structure is 0.13-λ and 0.29-λ thick, respectively. Given the compactness of the whole structure and the performance obtained, this quarter-wave plate is presented as a competitive device for the terahertz band.
Open Access
Electromagnetic response of extraordinary transmission plates inspired on Babinet’s principle
(InTech, 2011) Navarro Cía, Miguel; Beruete Díaz, Miguel; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This chapter is devoted to polarization effects arisen from perforated metallic plates exhibiting extraordinary transmission (ET). Setting aside the state-of-the-art of perforated metallic plates, we show that by applying Babinet’s principle, subwavelength hole arrays (SHAs) arranged in rectangular lattice can further enhance its potential polarization response. Different perspectives are brought about to describe and understand the particular behaviour of self-complementariness-based SHAs: Babinet’s principle, equivalent circuit analysis, retrieved constitutive parameters, etc. Afterwards, we embark on the numerical analysis of stacked self-complementariness-based perforated plates. It is shown the potential of having a birefringent artificial medium behaving like negative and positive effective refractive index for the vertical and horizontal polarization, respectively. All these findings are experimentally demonstrated at millimetre-waves.
Open Access
Extraordinary THz transmission with a small beam spot: the leaky wave mechanism
(Wiley, 2018) Navarro Cía, Miguel; Pacheco-Peña, Víctor; Kuznetsov, Sergei A.; Beruete Díaz, Miguel; Institute of Smart Cities - ISC
The discovery of extraordinary optical transmission (EOT) through patterned metallic foils in the late 1990s was decisive for the development of plasmonics and cleared the path to employ small apertures for a variety of interesting applications all along the electromagnetic spectrum. However, a typical drawback often found in practical EOT structures is the large size needed to obtain high transmittance peaks. Consequently, practical EOT arrays are usually illuminated using an expanded (mimicking a plane wave) beam. Here, it is shown with numerical and experimental results in the THz range that high transmittance peaks can be obtained even with a reduced illumination spot exciting a small number of holes, provided that the structure has a sufficient number of lateral holes out of the illumination spot. These results shed more light on the prominent role of leaky waves in the underlying physics of EOT and have a direct impact on potential applications.
Open Access
Extraordinary transmission and left-handed propagation in miniaturized stacks of doubly periodic subwavelength hole arrays
(Optical Society of America, 2007) Beruete Díaz, Miguel; Sorolla Ayza, Mario; Navarro Cía, Miguel; Falcone Lanas, Francisco; Campillo, Igor; Lomakin, Vitaliy; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
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 peaks in the transmittance frequency dependence. Stacks of such perforated plates support ET phenomena with propagation along the stack axis that is characterized by the left handed behavior. The incorporation of the dielectric materials and dense periodicity allows significantly reducing the illuminated area of the perforated plate required experimentally to observe the ET phenomena as compared to the areas required in the case of free standing rectangular hole arrays. This facilitates the experimental investigation of ET under excitation in the Fresnel zone of Gaussian beams.
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 Publikoa
We 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.