arXiv subjects

Willie J. Padilla

Publications and source records attributed to Willie J. Padilla.

22 records · Page 2Linked to original sources

arXiv2011

Taming the Blackbody with Metamaterials

In this paper we demonstrate, for the first time, selective thermal emitters based on metamaterials perfect absorbers. We experimentally realize a narrow band mid-infrared (MIR) thermal emitter. Multiple metamaterial sublattices further permit construction of a dual-band MIR emitter. By performing both emissivity and absorptivity measurements, we find that emissivity and absorptivity agree very well as predicted by Kirchhoff's law of thermal radiation. Our results directly demonstrate the great flexibility of metamaterials for tailoring blackbody emission.

cond-mat.other↗

arXiv2010

An Infrared Spatial and Frequency Selective Metamaterial Perfect Absorber

We demonstrate, for the first time, a spatially dependent metamaterial perfect absorber operating in the infrared regime. We achieve an experimental absorption of 97% at a wavelength of 6.0 microns, and our results agree well with numerical full-wave simulations. By using two different metamaterial sublattices we experimentally demonstrate a spatial and frequency varying absorption which may have many relevant applications including hyperspectral sub-sampling imaging

cond-mat.mes-hall↗

arXiv2008

Planar wallpaper group metamaterial for novel terahertz applications

We present novel metamaterial structures based upon various planar wallpaper groups, in both hexagonal and square unit cells. An investigation of metamaterials consisting of one, two, and three unique sub-lattices with resonant frequencies in the terahertz (THz) was performed. We describe the theory, and perform simulations and experiments to characterize these multiple element metamaterials. A method for using these new structures as a means for bio / chemical hazard detection, as well as electromagnetic signature control is proposed.

cond-mat.mtrl-sci↗

arXiv2008

A metamaterial absorber for the terahertz regime: Design, fabrication and characterization

We present a metamaterial that acts as a strongly resonant absorber at terahertz frequencies. Our design consists of a bilayer unit cell which allows for maximization of the absorption through independent tuning of the electrical permittivity and magnetic permeability. An experimental absorptivity of 70% at 1.3 terahertz is demonstrated. We utilize only a single unit cell in the propagation direction, thus achieving an absorption coefficient $α$ = 2000 cm$^{-1}$. These metamaterials are promising candidates as absorbing elements for thermally based THz imaging, due to their relatively low volume, low density, and narrow band response.

cond-mat.mtrl-sci↗