Powerful surface-wave oscillators with two-dimensional periodic structures

2012 ◽  
Vol 100 (14) ◽  
pp. 143510 ◽  
Author(s):  
N. S. Ginzburg ◽  
A. M. Malkin ◽  
A. S. Sergeev ◽  
V. Yu. Zaslavsky
Keyword(s):  
Surface Wave ◽  
Periodic Structures ◽  
Two Dimensional

Relativistic surface-wave generators based on two-dimensional periodic structures

2012 ◽  
Vol 38 (2) ◽  
pp. 188-192 ◽  
Author(s):  
N. S. Ginzburg ◽  
V. Yu. Zaslavskii ◽  
A. M. Malkin ◽  
A. S. Sergeev
Keyword(s):  
Surface Wave ◽  
Periodic Structures ◽  
Two Dimensional

Steady detonation propagation in a circular arc: a Detonation Shock Dynamics model

2016 ◽  
Vol 807 ◽  
pp. 87-134 ◽  
Author(s):  
Mark Short ◽  
James J. Quirk ◽  
Chad D. Meyer ◽  
Carlos Chiquete
Keyword(s):  
Surface Wave ◽  
Angular Speed ◽  
Order Correction ◽  
Two Dimensional ◽  
Normal Surface ◽  
Circular Arc ◽  
First Order ◽  
Shock Dynamics ◽  
First Order Correction ◽  
Steady Detonation

We study the physics of steady detonation wave propagation in a two-dimensional circular arc via a Detonation Shock Dynamics (DSD) surface evolution model. The dependence of the surface angular speed and surface spatial structure on the inner arc radius ($R_{i}$), the arc thickness ($R_{e}-R_{i}$, where $R_{e}$ is the outer arc radius) and the degree of confinement on the inner and outer arc is examined. We first analyse the results for a linear $D_{n}$–$\unicode[STIX]{x1D705}$ model, in which the normal surface velocity $D_{n}=D_{CJ}(1-B\unicode[STIX]{x1D705})$, where $D_{CJ}$ is the planar Chapman–Jouguet velocity, $\unicode[STIX]{x1D705}$ is the total surface curvature and $B$ is a length scale representative of a reaction zone thickness. An asymptotic analysis assuming the ratio $B/R_{i}\ll 1$ is conducted for this model and reveals a complex surface structure as a function of the radial variation from the inner to the outer arc. For sufficiently thin arcs, where $(R_{e}-R_{i})/R_{i}=O(B/R_{i})$, the angular speed of the surface depends on the inner arc radius, the arc thickness and the inner and outer arc confinement. For thicker arcs, where $(R_{e}-R_{i})/R_{i}=O(1)$, the angular speed does not depend on the outer arc radius or the outer arc confinement to the order calculated. It is found that the leading-order angular speed depends only on $D_{CJ}$ and $R_{i}$, and corresponds to a Huygens limit (zero curvature) propagation model where $D_{n}=D_{CJ}$, assuming a constant angular speed and perfect confinement on the inner arc surface. Having the normal surface speed depend on curvature requires the insertion of a boundary layer structure near the inner arc surface. This is driven by an increase in the magnitude of the surface wave curvature as the inner arc surface is approached that is needed to meet the confinement condition on the inner arc surface. For weak inner arc confinement, the surface wave spatial variation with the radial coordinate is described by a triple-deck structure. The first-order correction to the angular speed brings in a dependence on the surface curvature through the parameter $B$, while the influence of the inner arc confinement on the angular velocity only appears in the second-order correction. For stronger inner arc confinement, the surface wave structure is described by a two-layer solution, where the effect of the confinement on the angular speed is promoted to the first-order correction. We also compare the steady-state arc solution for a PBX 9502 DSD model to an experimental two-dimensional arc geometry validation test.

scholarly journals Two-dimensional photonic crystals increasing vertical light emission from Si nanocrystal-rich thin layers

2018 ◽  
Vol 9 ◽  
pp. 2287-2296
Author(s):  
Lukáš Ondič ◽  
Marian Varga ◽  
Ivan Pelant ◽  
Alexander Kromka ◽  
Karel Hruška ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Light Emission ◽  
Periodic Structures ◽  
Normal Direction ◽  
Thin Layers ◽  
Two Dimensional ◽  
Lattice Constants ◽  
Leaky Modes ◽  
Si Nanocrystals ◽  
Si Nanocrystal

We have fabricated two-dimensional photonic crystals (PhCs) on the surface of Si nanocrystal-rich SiO2 layers with the goal to maximize the photoluminescence extraction efficiency in the normal direction. The fabricated periodic structures consist of columns ordered into square and hexagonal pattern with lattice constants computed such that the red photoluminescence of Si nanocrystals (SiNCs) could couple to leaky modes of the PhCs and could be efficiently extracted to surrounding air. Samples having different lattice constants and heights of columns were investigated in order to find the configuration with the best performance. Spectral overlap of the leaky modes with the luminescence spectrum of SiNCs was verified experimentally by measuring photonic band diagrams of the leaky modes employing angle-resolved spectroscopy and also theoretically by computing the reflectance spectra. The extraction enhancement within different spatial angles was evaluated by means of micro-photoluminescence spectroscopy. More than 18-fold extraction enhancement was achieved for light propagating in the normal direction and up to 22% increase in overall intensity was obtained at the spatial collection angle of 14°.

Oversized co-axial and cylindrical surface-wave oscillators with two-dimensional periodical grating (quasi-optical model)

2013 ◽  
Vol 113 (10) ◽  
pp. 104504 ◽  
Author(s):  
N. S. Ginzburg ◽  
A. M. Malkin ◽  
A. S. Sergeev ◽  
V. Yu. Zaslavsky
Keyword(s):  
Surface Wave ◽  
Cylindrical Surface ◽  
Optical Model ◽  
Two Dimensional

Wave Propagation in Two-Dimensional Nonlinear Periodic Lattices

2009 ◽  
Author(s):  
Raj K. Narisetti ◽  
Massimo Ruzzene ◽  
Michael J. Leamy
Keyword(s):  
Wave Propagation ◽  
Linear Models ◽  
Periodic Structures ◽  
Harmonic Wave ◽  
Excitation Amplitude ◽  
Pass Band ◽  
Perturbation Approach ◽  
Nonlinear Stiffness ◽  
Two Dimensional ◽  
Low Amplitude

This paper investigates wave propagation in two-dimensional nonlinear periodic structures subject to point harmonic forcing. The infinite lattice is modeled as a springmass system consisting of linear and cubic-nonlinear stiffness. The effects of nonlinearity on harmonic wave propagation are analytically predicted using a novel perturbation approach. Response is characterized by group velocity contours (derived from phase-constant contours) functionally dependent on excitation amplitude and the nonlinear stiffness coefficients. Within the pass band there is a frequency band termed the “caustic band” where the response is characterized by the appearance of low amplitude regions or “dead zones.” For a two-dimensional lattice having asymmetric nonlinearity, it is shown that these caustic bands are dependent on the excitation amplitude, unlike in corresponding linear models. The analytical predictions obtained are verified via comparisons to responses generated using a time-domain simulation of a finite two-dimensional nonlinear lattice. Lastly, the study demonstrates amplitude-dependent wave beaming in two-dimensional nonlinear periodic structures.

Scattering of a Rayleigh Wave by an Elastic Quarter Space

1985 ◽  
Vol 52 (3) ◽  
pp. 664-668 ◽  
Author(s):  
A. K. Gautesen
Keyword(s):  
Steady State ◽  
Surface Wave ◽  
Fourier Transforms ◽  
Two Dimensional ◽  
Rayleigh Surface Wave ◽  
State Problem ◽  
Free Surfaces ◽  
Linear Elastic ◽  
Quarter Space ◽  
Steady State Problem

We study the two-dimensional, steady-state problem of the scattering of waves in a homogeneous, isotropic, linear-elastic quarter space. We derive decoupled equations for the Fourier transforms of the normal and tangential displacements on the free surfaces. For incidence of a Rayleigh surface wave, we plot the amplitudes and phases of the surface waves reflected and transmitted by the corner. These curves were obtained numerically.

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