Experimental Demonstration of Effective Medium Approximation Breakdown in Deeply Subwavelength All-Dielectric Multilayers.

We report the first experimental demonstration of anomalous breakdown of the effective medium approximation in all-dielectric deeply subwavelength thickness (d∼λ/160-λ/30) multilayers, as recently predicted theoretically [H. H. Sheinfux et al.

Dark-field hyperlens: Super-resolution imaging of weakly scattering objects.

We propose a device for subwavelength optical imaging based on a metal-dielectric multilayer hyperlens designed in such a way that only large-wavevector (evanescent) waves are transmitted while all propagating (small-wavevector) waves from the object area are blocked by the hyper-lens. We numerically demonstrate that as the result of such filtering, the image plane only contains scattered light from subwavelength features of the objects and is completely free from background illumination. Similar in spirit to conventional dark-field microscopy, the proposed dark-field hyperlens is shown to enhance the subwavelength image contrast by more than two orders of magnitude.

Water: Promising Opportunities For Tunable All-dielectric Electromagnetic Metamaterials.

We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric resonances in a metamaterial consisting of periodically positioned water-filled reservoirs. The proposed water-based metamaterials can find applications not only as cheap and ecological microwave devices, but also in optical and terahertz metamaterials prototyping and educational lab equipment.

Anomalous effective medium approximation breakdown in deeply subwavelength all-dielectric photonic multilayers.

We present a comprehensive analysis of the applicability of the effective medium approximation to deeply subwavelength (period ≤λ/50 all-dielectric multilayer structures. We demonstrate that even though the dispersion relations for such multilayers differ from the effective medium prediction only slightly, there can be regimes when an actual multilayer stack exhibits significantly different properties compared to its homogenized model. In particular, reflection near the critical angle is shown to strongly depend on even very small period variations, as well as on the choice of the multilayer termination.

Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator.

We propose new designs of plasmonic modulators, which can be used for dynamic signal switching in photonic integrated circuits. We study performance of a plasmonic waveguide modulator with bismuth ferrite as a tunable material. The bismuth ferrite core is sandwiched between metal plates (metal-insulator-metal configuration), which also serve as electrodes.

Rough metal and dielectric layers make an even better hyperbolic metamaterial absorber.

We numerically investigate the influence of roughness in layer thicknesses on the properties of hyperbolic metamaterials (HMMs). We show that random spatial variation of dielectric and metal layer thicknesses, similar to what occurs during actual structure fabrication, leads to dramatic absorption increase compared to an ideal, smooth-layer HMM; the absorption increases more strongly when roughness is induced throughout the HMM rather than in its surface layer only. Hence, we have found that moderate surface roughness does not deteriorate the HMM functionality, at least in absorption-related applications, thus eliminating the challenge of ultrasmooth metal layer fabrication.

Internal photoemission from plasmonic nanoparticles: comparison between surface and volume photoelectric effects.

We study the emission of photoelectrons from plasmonic nanoparticles into a surrounding matrix. We consider two mechanisms of electron emission from the nanoparticles--surface and volume ones--and use models for these two mechanisms which allow us to obtain analytical results for the photoelectron emission rate from a nanoparticle. Calculations have been carried out for a step potential at the surface of a spherical nanoparticle, and a simple model for the hot electron cooling has been used.

Inherent polarization entanglement generated from a monolithic semiconductor chip.

Creating miniature chip scale implementations of optical quantum information protocols is a dream for many in the quantum optics community. This is largely because of the promise of stability and scalability. Here we present a monolithically integratable chip architecture upon which is built a photonic device primitive called a Bragg reflection waveguide (BRW).

Physical nature of volume plasmon polaritons in hyperbolic metamaterials.

We investigate electromagnetic wave propagation in multilayered metal-dielectric hyperbolic metamaterials (HMMs). We demonstrate that high-k propagating waves in HMMs are volume plasmon polaritons. The volume plasmon polariton band is formed by coupling of short-range surface plasmon polariton excitations in the individual metal layers.

Dipole radiation near hyperbolic metamaterials: applicability of effective-medium approximation.

We investigate the radiation rate of a dipole in close proximity to a hyperbolic metamaterial and confirm that both the radiation rate and its fraction directed into the metamaterial are greatly increased compared to bulk dielectric or metal. However, we find that the homogenized effective-medium approach greatly overestimates the Purcell factor compared to metal-dielectric subwavelength multilayers with previously reported layer thicknesses.

Plasmonic rod dimers as elementary planar chiral meta-atoms.

We theoretically calculate the electromagnetic response of metallic rod dimers for the arbitrary planar arrangement of rods in the dimer. It is shown that dimers without an in-plane symmetry axis exhibit elliptical dichroism and act as "atoms" in planar chiral metamaterials. Because of a very simple geometry of the rod dimer, such planar metamaterials are much easier to fabricate than conventional split-ring or gammadion-type structures and lend themselves to a simple analytical treatment based on a coupled dipole model.

Optical memory based on ultrafast wavelength switching in a bistable microlaser.

We propose an optical memory cell based on ultrafast wavelength switching in coupled-cavity microlasers, featuring bistability between modes separated by several nanometers. A numerical implementation is demonstrated by simulating a two-dimensional photonic crystal microlaser. Switching times of less than 10 ps, switching energy around 15-30 fJ, and on-off contrast of more than 40 dB are achieved.

Elliptical dichroism: operating principle of planar chiral metamaterials.

We employ a homogenization technique based on the Lorentz electronic theory to show that planar chiral structures (PCSs) can be described by an effective dielectric tensor similar to that of biaxial elliptically dichroic crystals. Such a crystal is shown to behave like a PCS insofar as it exhibits its characteristic optical properties, namely, corotating elliptical polarization eigenstates and asymmetric, direction-dependent transmission for left- or right-handed incident wave polarization.

Switchable lasing in multimode microcavities.

We propose the new concept of a switchable multimode microlaser. As a generic, realistic model of a multimode microresonator a system of two coupled defects in a two-dimensional photonic crystal is considered. We demonstrate theoretically that lasing of the cavity into one selected resonator mode can be caused by injecting an appropriate optical pulse at the onset of laser action (injection seeding).