Yu. A. Barnakov

Controlling spontaneous emission with metamaterials

We have observed, in metamaterial with hyperbolic dispersion (an array of silver nanowires in alumina membrane), a sixfold reduction of the emission lifetime of dye deposited onto the metamaterials surface. This serves as evidence of an anomalously high density of photonic states in hyperbolic metamaterials, demonstrates the feasibility of an earlier-predicted single-photon gun, and paves the road for the use of metamaterials in quantum optics.

Bulk photonic metamaterial with hyperbolic dispersion

We have demonstrated the thickest bulk photonic metamaterial reported in the literature based on an Ag-filled alumina membrane. The material is highly anisotropic with hyperbolic dispersion at λ>0.84 μm. The refraction of light in the direction expected of isotropic media with n<1 has been experimentally demonstrated at λ=632.8 nm. This makes the material potentially suitable for a variety of applications ranging from subdiffraction imaging to optical cloaking.

Transparent conductive oxides: Plasmonic materials for telecom wavelengths

We show that despite of low loss, silver and gold are not suitable for a variety of nanoplasmonic applications in the infrared range, which require compact modes in single-interface plasmonic waveguides. At the same time, degenerate wide-band-gap semiconductors can serve as high-quality plasmonic materials at telecom wavelengths, combining fairly high compactness and relatively low loss. Their plasmonic properties in the near-infrared can be compared to those of gold in the visible range. The same materials can be used in a variety of non-plasmonic metamaterials applications, including transformation optics and invisibility cloaking.

Control of spontaneous emission in a volume of functionalized hyperbolic metamaterial

We have developed a simple method to fabricate lamellar metal-dielectric hyperbolic metamaterials on flat, flexible, and curvilinear substrates, which allows for functionalization of dielectric layers by dye molecules. The control of spontaneous emission of dye molecules with hyperbolic metamaterials has been studied in two different sample configurations, and the effect has been found to be much stronger when emitters are placed inside the metamaterial rather than on its surface.

Uniaxial epsilon-near-zero metamaterial for angular filtering and polarization control

We describe a unique class of metamaterials that exhibit strong uniaxial anisotropy with epsilon-zero response along the optical axis and which optical properties depend strongly on polarization. In an example of array of silver nanowires grown in anodic alumina membrane, the proposed singular uniaxial metamaterial is shown to function as a polarizer and narrowband angular transmittance filter.

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.

Effect of metallic surface on electric dipole and magnetic dipole emission transitions in Eu 3+ doped polymeric film

Spontaneous emission of Eu(3+) ions is studied in thin organic films deposited onto several different substrates. It has been demonstrated that the presence of a metallic surface in close vicinity to emitting Eu(3+) ions causes modifications of their spontaneous emission spectra, in particular, the change in the relative strengths of magnetic-dipole and electric-dipole transitions. The character and the magnitude of the effect depend on the polarization and the observation angle. The experimental data are discussed in terms of modification of transition probabilities and account for the interference between directly emitted and reflected light waves.

Darker than black: radiation-absorbing metamaterial

Taking advantage of the broadband “super-singularity” in the density of states of hyperbolic metamaterials, we develop a new approach to radiation-absorbing systems and present an experimental realization of this concept.

Simple route to Nd:YAG transparent ceramics

We report on the fabrication and spectroscopic characterization of transparent Nd3+:YAG ceramic, a prospective material for future laser applications.

Toward curvilinear metamaterials based on silver-filled alumina templates [Invited]

The method of fabrication of bulk three-dimensional curvilinear metamaterials based on metallic nanowires grown in porous alumina membranes was developed. Morphologically, fabricated structures resemble those earlier proposed for the design of an optical cloak and a hyperlens. Feasibility and flexibility of the suggested technological platform paws the road to engineering novel curvilinear hyperbolic metamaterials via inexpensive non-lithographic routes.