Mid-infrared plasmonic inductors: enhancing inductance with meandering lines.

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 17 THz upholding unification of plasmonics and microwave concepts and allowing for a simplification of structure design and analysis; in practical terms, a broadband funnelling of infrared 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.

Terahertz epsilon-near-zero graded-index lens.

An 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.

Dual-band double-negative-index fishnet metamaterial at millimeter-waves.

An effective negative refractive index (NRI) is demonstrated and experimentally verified for the first two propagation bands of a fishnet-like metamaterial at millimeter-wave frequencies. The dual-band NRI behavior is achieved by engineering the diffraction order (±1, ±1) associated with the internal mode supported between holey layers to correspond with the second propagation band. In addition to the experimental interferometric technique that accounts for the handedness of the propagation, numerical results are given to predict the dual-band effective NRI and to confirm dual-band negative refraction for a prism composed of the proposed metamaterial.

Millimeter-wave phase resonances in compound reflection gratings with subwavelength grooves.

Experimental evidence of phase resonances in a dual-period reflection structure comprising three subwavelength grooves in each period is provided in the millimeter-wave regime. We have analyzed and measured the response of these structures and show that phase resonances are characterized by a minimum in the reflected response, as predicted by numerical calculations. It is also shown that under oblique incidence these structures exhibit additional phase resonances not present for normal illumination because of the potentially permitted odd field distribution.

Broadband spoof plasmons and subwavelength electromagnetic energy confinement on ultrathin metafilms.

A complementary split ring resonator (CSRR)-based metallic layer is proposed as a route to mimic surface plasmon polaritons. A numerical analysis of the textured surface is carried out and compared to previous prominent topologies such as metal mesh, slit array, hole array, and Sievenpiper mushroom surfaces, which are studied as well from a transmission line perspective. These well-documented geometries suffer from a narrowband response, alongside, in most cases, metal thickness constraint (usually of the order of lambda/4) and non-subwavelength modal size as a result of the large dimensions of the unit cell (one dimensions is at least of the order of lambda/2).

Polarized left-handed extraordinary optical transmission of subterahertz waves.

In this paper we design and measure a metamaterial polarizing device working in the sub-terahertz range. The polarizer is based on a modified version of our previous miniaturized Stacked Hole Array (SHA) structure, an arrangement that combines Extraordinary Optical Transmission (EOT) and Left-Handed Metamaterial (LHM) propagation even under Fresnel illumination. Here, we use a self complementary screen by connecting the holes of an EOT structure.

Extraordinary transmission and left-handed propagation in miniaturized stacks of doubly periodic subwavelength hole arrays.

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.

Left-handed extraordinary optical transmission through a photonic crystal of subwavelength hole arrays.

Metamaterial structures are artificial materials that show unconventional electromagnetic properties such as photonic band-gap, extraordinary optical transmission and left-handed propagation. Up to now, relations of photonic crystals and negative refraction have been shown as well as of photonic crystals and sub-wavelength hole arrays. Here we report a left-handed metamaterial engineered by a combination of sub-wavelength hole array plates periodically stacked to form a photonic crystal structure.