483 research outputs found
Unusual phase transition in 1D localization and its observability in optics
Localization of electrons in 1D disordered systems is usually described in
the random phase approximation, when distributions of phases \varphi and
\theta, entering the transfer matrix, are considered as uniform. In the general
case, the random phase approximation is violated, and the evolution equations
are written in terms of the Landauer resistance \rho and the combined phases
\psi=\theta-\varphi and \chi=\theta+\varphi. The distribution of the phase \psi
is found to exhibit an unusual phase transition at the point E_0 when changing
the electron energy E, which manifests itself in the appearance of the
imaginary part of \psi. The distribution of resistance P(\rho) has no
singularity at the point E_0, and the transition seems unobservable in the
framework of condensed matter physics. However, the theory of 1D localization
is immediately applicable to the scattering of waves propagating in a
single-mode optical waveguide. Modern optical methods open a way to measure
phases \psi and \chi. As a result, the indicated phase transition becomes
observable.Comment: Latex, 9 pages, 6 figures include
Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes
Photonic bandgap effect in disordered arrays of scatterers: implications to broadband, low-loss waveguiding
Ultra-thin titanium nitride films for refractory spectral selectivity
We demonstrate a selectively emitting optical Fabry-P\'erot resonator based
on a few-nm-thin continuous metallic titanium nitride film, separated by a
dielectric spacer from an optically thick titanium nitride back-reflector,
which exhibits excellent stability at 1070 K against chemical degradation,
thin-film instabilities and melting point depression. The structure paves the
way to the design and fabrication of refractory thermal emitters using the
well-established processes known from the field of multilayer and rugate
optical filters. We demonstrate that a few-nanometer thick films of titanium
nitride can be stable under operation at temperatures exceeding 1070 K. This
type of selective emitter provides a means towards near-infrared thermal
emission that could potentially be tailored to the accuracy level known from
rugate optical filters.Comment: 16 pages, 6 figure
Statistical properties of spontaneous emission near a rough surface
We study the lifetime of the excited state of an atom or molecule near a
plane surface with a given random surface roughness. In particular, we discuss
the impact of the scattering of surface modes within the rough surface. Our
study is completed by considering the lateral correlation length of the decay
rate and the variance discussing its relation to the C0 correlation
The exact solution of self-consistent equations in the scanning near-field optic microscopy problem
The macroscopic approach that allows one to obtain an exact solution of the self-consistent equation of the Lippmann-Schwinger type is developed. The main idea of our method consist in usage of diagram technique for exact summation of the infinite series corresponding to the iteration procedure for solving the self-consistent integral equation. The method developed is applied to calculations of near-field optical images obtained in illumination mode. It is assumed that the system under consideration consists of an object illuminated by the field scattered by a small probe. This assumption allows us to consider multiple scattering between a (point-like) probe and an extended object as well as inside the object. The exact solution for the self-consistent field is then obtained in terms of effective susceptibility of the probe-object system. Application of our method to the description of orientation of molecular complexes at the surface is discussed
Self consistent determination of plasmonic resonances in ternary nanocomposites
We have developed a self consistent technique to predict the behavior of
plasmon resonances in multi-component systems as a function of wavelength. This
approach, based on the tight lower bounds of the Bergman-Milton formulation, is
able to predict experimental optical data, including the positions, shifts and
shapes of plasmonic peaks in ternary nanocomposites without using any ftting
parameters. Our approach is based on viewing the mixing of 3 components as the
mixing of 2 binary mixtures, each in the same host. We obtained excellent
predictions of the experimental optical behavior for mixtures of Ag:Cu:SiO2 and
alloys of Au-Cu:SiO2 and Ag-Au:H2 O, suggesting that the essential physics of
plasmonic behavior is captured by this approach.Comment: 7 pages and 4 figure
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