Bulk photonic metamaterial with hyperbolic dispersion

In this work, we demonstrate a self-standing bulk three-dimensional metamaterial based on the network of silver nanowires in an alumina membrane. This constitutes an anisotropic effective medium with hyperbolic dispersion, which can be used in sub-diffraction imaging or optical cloaks. Highly anisotropic dielectric constants of the material range from positive to negative, and the transmitted laser beam shifts both toward the normal to the surface, as in regular dielectrics, and off the normal, as in anisotropic dielectrics with the refraction index smaller than one. The designed photonic metamaterial is the thickest reported in the literature, both in terms of its physical size 1cm x 1cm x 51 mm, and the number of vacuum wavelengths, N=61 at l=0.84 mm.Comment: 6 pages, 4 figur

Magneto-optical spectra of closely spaced magnetite nanoparticles

The Faraday rotation spectrum of composites containing magnetite nanoparticles is found to be dependent on the interparticle spacing of the constituent nanoparticles. The composite materials are prepared by combining chemically synthesized Fe 3O4 smagnetited nanoparticles s8-nm diameterd and polysmethylmethacrylated . Composites are made containing a range of nanoparticle concentrations. The peak of the main spectral feature depends on nanoparticle concentration; this peak is observed to shift from approximately 470 nm for sdilute compositesd to 540 nm concentrated . We present a theory based on the discrete-dipole approximation which accounts for optical coupling between magnetite particles. Qualitative correlations between theoretical calculations and experimental data suggest that the shifts in spectral peak position depend on both interparticle distance and geometrical configuratio

Highly Porous Carbon Materials Filled with Nickel Hydroxide Nanoparticles; Synthesis, Study, Application in Electrochemistry

Nickel hydroxide was deposited on the surface of the porous carbon to obtain a cathode material for  supercapacitors. This work is the first part of the study of Ni(OH)2/С composite, which considers the conditions of its synthesis using two types of porous carbon matrices with a highly developed specific surface area (1000–3000 m2/g) and two types of precursors (NiCl2*6H2O and Ni(N3)2). The morphology of the systems, in particular the shape and size characteristics of the hydroxide filler particles, was examined using the scanning electron microscopy, X-ray diffraction, and nitrogen adsorption-desorption at 77 K. The measurements of capacity of the Ni(OH)2/С-electrodes were made in 6 M KOH using an asymmetric two-electrode cell (a porous carbon material with known electrode characteristics was employed as the counter electrode). The capacity was shown to decrease by 22–56% with increasing the scanning rate from 10 to 80 mV/s. A maximum capacity of the composite was obtained at a scanning rate of 10 mV/s was 346 F/g

Reduced reflection from roughened hyperbolic metamaterial

We show that roughened surfaces of hyperbolic metamaterials scatter light preferentially inside the media, resulting in a very low reflectance. This phenomenon of fundamental importance, demonstrated experimentally in arrays of silver nanowires grown in alumina membranes, is consistent with a broad-band singularity in the density of photonic states. It paves the road to a variety of applications ranging from the stealth technology to high-efficiency solar cells and photodetectors. (C) 2013 Optical Society of Americ

Broadband radiation-absorbing metamaterial

Using the broadband super-singularity in the density of states of (meta) materials with hyperbolic dispersion, we demonstrate, both theoretically and experimentally, a new concept of radiation-absorbing systems