arXiv subjects

Richard D. Averitt

Publications and source records attributed to Richard D. Averitt.

40 records · Page 3Linked to original sources

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

Electronic control of extraordinary terahertz transmission through subwavelength metal hole arrays

We describe the electronic control of extraordinary terahertz transmission through subwavelength metal hole arrays fabricated on doped semiconductor substrates. The hybrid metal-semiconductor forms a Schottky diode structure, where the active depletion region modifies the substrate conductivity in real-time by applying an external voltage bias. This enables effective control of the resonance enhanced terahertz transmission. Our proof of principle device achieves an intensity modulation depth of 52% by changing the voltage bias between 0 and 16 volts. Further optimization may result in improvement of device performance and practical applications. This approach can be also translated to the other optical frequency ranges.

physics.optics↗

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↗

arXiv2001

Josephson Plasma Resonance in Tl$_2$Ba$_2$CaCu$_2$O$_8$ in a Magnetic Field Measured using THz Spectroscopy

We report the first measurements of the $c$-axis Josephson Plasma Resonance (JPR) in Tl$_2$Ba$_2$CaCu$_2$O$_8$ as a function of temperature with and without a $c$-axis magnetic field using terahertz time-domain spectroscopy in transmission. The JPR is sensitive to the alignment of pancake vortices along the $c$-axis, and is observed to decrease when applying a magnetic field as expected.

cond-mat.supr-con↗