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

Photoelectric, nonlinear optical, and photorefractive properties of polymer composites including carbon nanotubes and cyanine dyes

The effect of cyanine dye additives on the photoelectric, nonlinear optical, and photorefractive properties of polyvinyl carbazole composites based on closed single-walled carbon nanotubes has been investigated. It has been found that these characteristics are affected by the dye in which the lowest unoccupied molecular orbital (LUMO) lies below the level of the photoexcited nanotube. The addition of this dye to the composite leads to a 14-fold increase in the quantum efficiency of the generation of mobile charge carriers under irradiation by a laser (1064 nm) in the absorption region of the nanotubes. Moreover, the addition of the dye to the composite decreases the third-order susceptibility χ (3) , presumably, due to the opposite orientations of dipoles of the dye and the nanotube upon adsorption of the dye on the nanotube. The addition of the dye to the composite also provides a twofold increase in the two-beam photorefractive amplification factor of the laser beam with a wavelength of 1064 nm. The obtained values of the two-beam photorefractive amplification factor reach 120 cm -1 . \ua9 2013 Pleiades Publishing, Ltd

Photoelectric and photorefractive properties of polyvinylcarbazole composites with graphene in the visible spectral range

The photoelectric and photorefractive characteristics of polyvinylcarbazole (PVK) composites with 0.15 wt % graphene at a wavelength of 532 nm have been measured. The dependence of the quantum efficiency of generation of mobile charge carriers as determined from the photocurrent is well approximated by the Onsager equation calculated accurate to E (0) (3) for the quantum yield of thermalized electron-hole pairs of phi(0) = 1 and their initial separation radius of r (0) = 10.9 . The long-wavelength edge of optical absorption for PVK lies at 365 nm. Thus, the photogeneration of mobile carriers during illumination of the composite at 532 nm is due to photoexcitation of graphene. The measurement of the photorefractive properties has revealed that the two-beam coupling gain coefficient is I" = 50 cm(-1) at E (0) = 150 V/mu m and equal intensities of incident beams. It has been found that at E (0) = 83.3 V/mu m, the two-beam coupling gain coefficient increases from 8 to 14 cm(-1) as the ratio of incident beam intensities I (1)(0)/I (2)(0) increases from 1 to 2.4

Spatial patterns of larval settlement and early post-settlement survivorship of Mytilus galloprovincialis in a Galician Ría (NW Spain). Effect on recruitment success

10 páginas, 3 figuras, 7 tablasLarval settlement and recruitment play an important role on the population dynamics of marine benthic invertebrates, and are key factors in the management of aquaculture industries. In order to check the current strategies of mussel seed gathering from collector ropes in the Ria of Ares-Betanzos (NW Spain), this work analyses the seasonal and spatial variability of larval settlement and recruitment of the mussel Mytilus galloprovincialis, as well as the relationship between settlement and recruitment. Our results highlight the importance of the hydrographic characteristics of the Ría de Ares-Betanzos on the spatial distribution of larval settlement and on the early post-settlement mortality, which determines recruitment success. The spatial distribution of larval settlement, with higher abundances in the northern-shore but significant larval retention in the southern culture areas, is in agreement with the positive subtidal circulation of this embayment and the larger residence times in the southern shore. The positive subtidal circulation of the Ría favours larval transport from the culture areas located in the south to the northern shore, while the larger residence times allow larval retention in the southern shore. The strong linear relationship between settlement and recruitment suggest density-independent mortality and allowed estimating recruitment abundances and short-term survival rates. The highest and lowest post-settlement mortalities were registered at the most external and sheltered locations respectively, suggesting that the vulnerability to the hydrodynamic stress may be the main cause of early post-settlement mortality of mussel juveniles on suspended substrates. Our results confirm that the sheltered culture polygons located in the inner area of the Ría of Ares-Betanzos are favourable environments for the recruitment of Mytilus galloprovincialis spat, supporting the current strategies of seed gathering from collector ropes in the Ría of Ares-BetanzosThis work was supported by PROINSA-CSIC contract-project (CSIC0704101100001)Peer reviewe

Induced and Effective Gravity Theories in D=2

As a preparation for the study of {\it arbitrary} extensions of $d=2$ gravity we present a detailed investigation of $SO(N)$ supergravity. By gauging a chiral, nilpotent subgroup of the $OSp(N|2)$ Wess-Zumino-Witten model we obtain an all order expression for the effective action. Reality of the coupling constant imposes the usual restrictions on $c$ for $N=0$ and 1. No such restrictions appear for $N\geq 2$. For $N=2$, 3 and 4, no renormalizations of the coupling constant beyond one loop occur. These results are related to non-renormalization theorems for theories with extended supersymmetries. Arbitrary (super)extensions of $d=2$ gravity are then analyzed. The induced theory is represented by a WZW model for which a chiral, solvable group is gauged. From this, we obtain the effective action. All order expressions for both the coupling constant renormalization and the wavefunction renormalization are given. From this we classify all extensions of $d=2$ gravity for which the coupling constant gets at most a one loop renormalization. As an application of the general strategy, $N=4$ theories based on D(2,1,\a) and $SU(1,1|2)$, all $WA$ gravities and the $N=2$ $W_n$ models are treated in some detail.Comment: 58 pages, latex, LBL-33738, UCB-PTH-93/06, KUL-TF-93/0

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