Using Thin Films of Phase-Change Material for Active Tuning of Terahertz Waves Scattering on Dielectric Cylinders.

The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide (VO2) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO2, a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase.

Cultivating Mars: A Project-Based Learning Lab Analyzing an Oxygen Based Redox Reaction in Order to Design an Oxygen-Rich Environment on the Red Planet.

In a series of activities/labs, designed in a building block approach, whereas each subsequent lab builds into the next, students will explore the reactivity and production of oxygen in various biological and chemical systems. Through student-constructed analyses, participants will optimize oxygen-generating systems for the colonization of Mars, wherein their system will be used as part of a narrative to construct a livable habitat for future astronauts. Use of remote access technology to a Scanning Electron Microscope (SEM) with elemental analysis capabilities allows students to investigate their oxygen reaction via formation of iron oxide, resulting in rich multidimensional and contextualized scientific exploration in the chemistry classroom.

Validation of electromagnetic field enhancement in near-infrared through Sierpinski fractal nanoantennas.

We introduced fractal geometry to the conventional bowtie antennas. We experimentally and numerically showed that the resonance of the bowtie antennas goes to longer wavelengths, after each fractalization step, which is considered a tool to miniaturize the main bowtie structure. We also showed that the fractal geometry provides multiple hot spots on the surface, and it can be used as an efficient SERS substrate.

Unidirectional transmission in photonic-crystal gratings at beam-type illumination.

Unidirectional transmission is studied theoretically and experimentally for the gratings with one-side corrugations (non-symmetric gratings), which are based on two-dimensional photonic crystals composed of alumina rods. The unidirectional transmission appears at a fixed angle of incidence as a combined effect of the peculiar dispersion features of the photonic crystal and the properly designed corrugations. It is shown that the basic unidirectional transmission characteristics, which are observed at a plane-wave illumination, are preserved at Gaussian-beam and horn antenna illuminations.

Transmission enhancement through deep subwavelength apertures using connected split ring resonators.

We report astonishingly high transmission enhancement factors through a subwavelength aperture at microwave frequencies by placing connected split ring resonators in the vicinity of the aperture. We carried out numerical simulations that are consistent with our experimental conclusions. We experimentally show higher than 70,000-fold extraordinary transmission through a deep subwavelength aperture with an electrical size of lambda/31 x lambda/12 (width x length), in terms of the operational wavelength.

Frequency dependent steering with backward leaky waves via photonic crystal interface layer.

A Photonic Crystal (PC) with a surface defect layer (made of dimers) is studied in the microwave regime. The dispersion diagram is obtained with the Plane Wave Expansion Method. The dispersion diagram reveals that the dimer-layer supports a surface mode with negative slope.