The purpose of optical antennas is to convert the energy of free propagating radiation to localized energy, and vice versa. Although this is similar to what radio wave and microwave antennas do, optical antennas exploit the unique properties of metal nanostructures, which behave as strongly coupled plasmas at optical frequencies. It is hoped that optical antennas can increase the efficiency of ...

We investigate the possibility that Stark wave packets can be used as a source of shaped terahertz radiation. Calculations for the sodium atom reveal that the frequency and intensity of the THz emission can be controlled over a broad range by varying the parameters of the excitation pulse.

We define the radiation fields of solutions to critical semilinear wave equations in R3 and use them to define the scattering operator. We also prove a support theorem for the radiation fields with radial initial data. This extends the well known support theorem for the Radon transform to this setting and can also be interpreted as a Paley-Wiener theorem for the distorted nonlinear Fourier tran...

We propose a design of a dielectric (silicon nitride) optical leaky wave antenna (OLWA) with periodic semiconductor (silicon) corrugations, capable of producing narrow beam radiation. The optical antenna radiates a narrow beam because a leaky wave (LW) with low attenuation constant is excited at one end of the corrugated dielectric waveguide. We show that pointing angle, beam-width, and operati...

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. Two facts are noted: First, a guided (bounded) wave is present, propagating along the surface of the dimer-layer. Second, ...

according to high costs of phase shifters in antenna arrays, new methods for beam steering without phase shifter were introduced. frequency diverse array (fda) concept is another approach to beam steering problem. in this structure, the subsequent antenna elements are fed with stepped discrete frequencies causing continuous scanning of space in time. so a range-angle dependent scanning is made ...

The hydrogen atom is an important testing ground for fundamental theories. High resolution laser spectroscopy has provided cornerstones such as the measurement of fundamental constants, a test of quantum electrodynamics, and even the investigation of hadronic structure [1]. The recent production of antihydrogen atoms [2], albeit at almost the speed of light, has given prospect of a new field. P...

This study describes a semi-analytic solution of planar radiative shock waves in which the radiation model is grey nonequilibrium diffusion. The solution may be used to verify radiation-hydrodynamics codes. Comparisons are made with the equilibrium diffusion solutions of Lowrie and Rauenzahn [1]. Although the physics of radiative shocks are fairly well known, previous solutions have been approx...