2,322 research outputs found
A Superlens Based on Metal-Dielectric Composites
Pure noble metals are typically considered to be the materials of choice for
a near-field superlens that allows subwavelength resolution by recovering both
propagating and evanescent waves. However, a superlens based on bulk metal can
operate only at a single frequency for a given dielectric host. In this Letter,
it is shown that a composite metal-dielectric film, with an appropriate metal
filling factor, can operate at practically any desired wavelength in the
visible and near-infrared ranges. Theoretical analysis and simulations verify
the feasibility of the proposed lens.Comment: 15 pages, 4 figure
Translation of Nanoantenna Hot-Spots by a Metal-Dielectric Composite Superlens
We employ numerical simulations to show that highly localized, enhanced
electromagnetic fields, also known as "hot spots," produced by a periodic array
of silver nanoantennas can be spatially translated to the other side of a
metal-dielectric composite superlens. The proposed translation of the hot spots
enables surface-enhanced optical spectroscopy without the undesirable contact
of molecules with metal, and thus it broadens and reinforces the potential
applications of sensing based on field-enhanced fluorescence and
surface-enhanced Raman scattering.Comment: 9 pages, 4 figure
Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications
Optical properties of colloidal plasmonic titanium nitride nanoparticles are
examined with an eye on their photothermal via transmission electron microscopy
and optical transmittance measurements. Single crystal titanium nitride cubic
nanoparticles with an average size of 50 nm exhibit plasmon resonance in the
biological transparency window. With dimensions optimized for efficient
cellular uptake, the nanoparticles demonstrate a high photothermal conversion
efficiency. A self-passivating native oxide at the surface of the nanoparticles
provides an additional degree of freedom for surface functionalization.Comment: 17 pages, 4 figures, 1 abstract figur
Trapped Rainbow Techniques for Spectroscopy on a Chip and Fluorescence Enhancement
We report on the experimental demonstration of the broadband "trapped
rainbow" in the visible range using arrays of adiabatically tapered optical
nano waveguides. Being a distinct case of the slow light phenomenon, the
trapped rainbow effect could be applied to optical signal processing, and
sensing in such applications as spectroscopy on a chip, and to providing
enhanced light-matter interactions. As an example of the latter applications,
we have fabricated a large area array of tapered nano-waveguides, which exhibit
broadband "trapped rainbow" effect. Considerable fluorescence enhancement due
to slow light behavior in the array has been observed.Comment: 15 pages, 4 figures, Published in Applied Physics
Unidirectional Amplification and Shaping of Optical Pulses by Three-Wave Mixing with Negative Phonons
A possibility to greatly enhance frequency-conversion efficiency of
stimulated Raman scattering is shown by making use of extraordinary properties
of three-wave mixing of ordinary and backward waves. Such processes are
commonly attributed to negative-index plasmonic metamaterials. This work
demonstrates the possibility to replace such metamaterials that are very
challenging to engineer by readily available crystals which support elastic
waves with contra-directed phase and group velocities. The main goal of this
work is to investigate specific properties of indicated nonlinear optical
process in short pulse regime and to show that it enables elimination of
fundamental detrimental effect of fast damping of optical phonons on the
process concerned. Among the applications is the possibility of creation of a
family of unique photonic devices such as unidirectional Raman amplifiers and
femtosecond pulse shapers with greatly improved operational properties.Comment: 6 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1304.681
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