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Large-scale, electric currents flowing along magnetic field lines into the polar regions of Earth are thought to be the main contributors of the energy that powers the ionospheric aurora. However, we have found evidence for global contributions from electromagnetic waves (Alfven waves). Data that were collected from the Polar spacecraft over the course of 1 year show that the flow of wave electromagnetic energy at altitudes of 25,000 to 38,000 kilometers delineates the statistical auroral oval. The Poynting flux of individual events distributed along the auroral oval was larger than 5 ergs per square centimeter per second, which is sufficient to power auroral acceleration processes. This evidence suggests that in addition to magnetic field-aligned currents, the dayside and nightside aurora is globally powered by the energy flow of these high-attitude Alfven waves., Earth's aurora occurs statistically and often simultaneously in an oval-shaped belt (Fig. 1A) around the magnetic poles (1). Magnetic field lines connect this auroral oval to the magnetosphere, the region [...]

We studied the microwave reflectivity of a structured, near perfectly conducting substrate that was designed to verify the existence of a theoretically proposed new class of surface mode. Measurements of the mode's dispersion curve show that it correctly approaches the predicted asymptotic frequency; the curve also agrees well with that derived from a computer simulation. Modeling of the field distribution on resonance provides evidence of strong localization of the electric field at the interface and substantial power flow along the interface, thus verifying the surface plasmon-like nature of the mode., Conductors support electromagnetic surface waves (1, 2) over a broad range of frequencies, ranging from dc and radio frequencies up to the visible. These modes propagate along the interface with [...]

The routing and interconnection of optical signals through narrow channels and around sharp corners are important for large-scale all-optical circuit applications. A recent computational result suggests that photonic crystals may offer a novel way of achieving this goal by providing a mechanism for guiding light that is fundamentally different from traditional index guiding. Waveguiding in a photonic crystal and near 100 percent transmission of electromagnetic waves around sharp 90 degree corners were observed experimentally. Bending radii were made smaller than one wavelength., The efficient guiding and interconnection of light on a chip are important for telecommunication and optical computing applications (1, 2). Conventional dielectric waveguides can support guided modes along straight lines [...]

Nanoscience is by essence an interdisciplinary field in which traditional differences between disciplines vanish. On page 1607 of this issue, Muhlschlegel et al. (1) bridge the fields of electrical engineering [...]

Nonlinear Mixing of Electromagnetic Waves in Plasmas INTEREST IN NONLINEAR MIXING OF ELECTROMAGNETIC waves in plasmas (particularly beat-wave plasma interaction) began more than two decades ago with the theoretical paper [...]