Towards all-dielectric metamaterials and nanophotonics

We review a new, rapidly developing field of all-dielectric nanophotonics which allows to control both magnetic and electric response of structured matter by engineering the Mie resonances in high-index dielectric nanoparticles. We discuss optical properties of such dielectric nanoparticles, methods of their fabrication, and also recent advances in all-dielectric metadevices including couple-resonator dielectric waveguides, nanoantennas, and metasurfaces

Strongly subradiant states in planar atomic arrays

The optically trapped ensembles of atoms provide a versatile platform for storing and coherent manipulation of quantum information. However, efficient realization of quantum information processing requires long-lived quantum states protected from the decoherence e.g. via spontaneous emission. Here, we theoretically study collective dipolar oscillations in finite planar arrays of quantum emitters in free space and analyze mechanisms that govern the emergence of strongly subradiant collective states. We demonstrate that the external coupling between the collective states associated with the symmetry of the array and with the quasi-flat dispersion of the corresponding infinite lattice plays a crucial role in the boost of their radiative lifetime. We show that among different regular arrangements of the atoms the square atomic arrays support eigenstates with minimal radiative losses that scale with the total number of atoms $N_{tot}$ as $\propto N_{tot}^{-5}$

Coherent control of topological states in an integrated waveguide lattice

Topological photonics holds the promise for enhanced robustness of light localization and propagation enabled by the global symmetries of the system. While traditional designs of topological structures rely on lattice symmetries, there is an alternative strategy based on accidentally degenerate modes of the individual meta-atoms. Using this concept, we experimentally realize topological edge state in an integrated optical nanostructure based on the array of silicon nano-waveguides, each hosting a pair of degenerate modes at telecom wavelengths. Exploiting the hybrid nature of the topological mode formed by the superposition of waveguide modes with different symmetry, we implement coherent control of the topological edge state by adjusting the phase between the degenerate modes and demonstrating selective excitation of bulk or edge states. The resulting field distribution is imaged via third harmonic generation allowing us to quantify the localization of topological modes as a function of the relative phase of the excitations. Our results highlight the impact of engineered accidental degeneracies on the formation of topological phases, extending the opportunities stemming from topological nanophotonic systems.Comment: 17 pages, 4 figure

Bending of electromagnetic waves in all-dielectric particle array waveguides

We propose and demonstrate experimentally an alternative approach for realizing subwavelength photonic structures, exploiting the waveguiding properties of chains of high-index dielectric disks with both electric and magnetic dipole resonances. We reveal that the electromagnetic energy can be efficiently guided through sharp corners by means of the mode polarization conversion at waveguide bends. We confirm experimentally the guidance through a 90° bend in the microwave frequency range.This work was supported by the Ministry of Education and Science of the Russian Federation (Project 11.G34.31.0020, GOSZADANIE 2014/190, Zadanie No. 3.561.2014/K, 14.584.21.0009 10), by Russian Foundation for Basic Research, the Dynasty Foundation (Russia), the Australian Research Council via Future Fellowship Program (No. FT110100037), and the Australian National University

Methodology for Analyzing Competing Options for Air Management Systems at the Stage of Conceptual Design of Civil Aircraft's Complex of Onboard Systems

Analysis of competing options for the implementation of the system is a key task at the stage of conceptual design of aviation air conditioning systems as these systems have a great impact on the fuel efficiency of the entire aircraft. The decision about choice of competing options regarding not only the appearance of the system, but also a lot of different parameters including technical, technological and so on. In case of conceptual design missing parameters for a complex criterion can be replaced by an alternative risk level estimate. This article shows an example how to compare competing variants of the air management system at the stage of conceptual design and provides a methodology for selecting the key parameters of the comparison criterion. As a result, it is shown that vapor cycle cooling is more promising due to the wide possibilities of reducing the mass of components and increasing the overall cooling efficiency. For the air cycle, most of the possible solutions to increase efficiency have already been implemented now