44 research outputs found
Waveguiding properties of surface states in photonic crystals
We propose and analyze novel surface-state-based waveguides in bandgap
photonic crystals. We discuss surface mode band structure, field localization
and effect of imperfections on the waveguiding properties of the surface modes.
We demonstrate that surface-state-based waveguides can be used to achieve
directional emission out of the waveguide. We also discuss the application of
the surface-state waveguides as efficient light couplers for conventional
photonic crystal waveguides.Comment: 4 pages 5 figure
Personalized advertising as a means of data collection
This paper deals with the future of advertising and how it can affect the privacy of the Internet users. It explains why consumers are so mistrustful of advertisers, and how advertisers can earn back their customers’ trust
Effects of boundary roughness on a Q-factor of whispering-gallery-mode lasing microdisk cavities
We perform numerical studies of the effect of sidewall imperfections on the
resonant state broadening of the optical microdisk cavities for lasing
applications. We demonstrate that even small edge roughness causes a drastic
degradation of high-Q whispering gallery (WG) mode resonances reducing their
Q-values by many orders of magnitude. At the same time, low-Q WG resonances are
rather insensitive to the surface roughness. The results of numerical
simulation obtained using the scattering matrix technique, are analyzed and
explained in terms of wave reflection at a curved dielectric interface combined
with the examination of Poincare surface of sections in the classical ray
picture.Comment: 4 pages, 3 figure
Light propagation in nanorod arrays
We study propagation of TM- and TE-polarized light in two-dimensional arrays
of silver nanorods of various diameters in a gelatin background. We calculate
the transmittance, reflectance and absorption of arranged and disordered
nanorod arrays and compare the exact numerical results with the predictions of
the Maxwell-Garnett effective-medium theory. We show that interactions between
nanorods, multipole contributions and formations of photonic gaps affect
strongly the transmittance spectra that cannot be accounted for in terms of the
conventional effective-medium theory. We also demonstrate and explain the
degradation of the transmittance in arrays with randomly located rods as well
as weak influence of their fluctuating diameter. For TM modes we outline the
importance of skin-effect, which causes the full reflection of the incoming
light. We then illustrate the possibility of using periodic arrays of nanorods
as high-quality polarizers.Comment: 6 pages, 7 figure
Optical response of metal nanoparticle chains
We study the optical responses of metal nanoparticle chains. Multiple
scattering calculations are used to study the extinction cross sections of
silver nanosphere chains of finite length embedded in a glass matrix. The
transmission and reflection coefficients of periodic 2D arrays of silver
nanospheres are also calculated to understand the interaction between
nanoparticle chains. The results are in agreement with recent experiments. The
splitting of plasmon-resonance modes for different polarizations of the
incident light are explored. Results on the effect of disorder are also
presented.Comment: 9 pages, 10 figure
Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation
We report fabrication method and THz characterization of composite films
containing either aligned metallic (tin alloy) microwires or chalcogenide
As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber
fabrication technique using multi-step co-drawing of low-melting-temperature
metals or semiconductor glasses together with polymers. Fibers are then stacked
together and pressed into composite films. Transmission through metamaterial
films is studied in the whole THz range (0.1-20 THz) using a combination of
FTIR and TDS. Metal containing metamaterials are found to have strong
polarizing properties, while semiconductor containing materials are
polarization independent and could have a designable high refractive index.
Using the transfer matrix theory, we show how to retrieve the complex
polarization dependent refractive index of the composite films. We then detail
the selfconsistent algorithm for retrieving the optical properties of the metal
alloy used in the fabrication of the metamaterial layers by using an effective
medium approximation. Finally, we study challenges in fabrication of
metamaterials with sub-micrometer metallic wires by repeated stack-and-draw
process by comparing samples made using 2, 3 and 4 consecutive drawings. When
using metallic alloys we observe phase separation effects and nano-grids
formation on small metallic wires