scholarly journals Relaxed micromorphic modeling of the interface between a homogeneous solid and a band-gap metamaterial: New perspectives towards metastructural design

2017 ◽  
Vol 23 (12) ◽  
pp. 1485-1506 ◽  
Author(s):  
Angela Madeo ◽  
Gabriele Barbagallo ◽  
Manuel Collet ◽  
Marco Valerio d’Agostino ◽  
Marco Miniaci ◽  
...  
Keyword(s):  
Band Gap ◽  
Excellent Agreement ◽  
Continuum Model ◽  
Fem Simulation ◽  
Transmission Spectra ◽  
Reflection And Transmission ◽  
Indirect Measure ◽  
Material Parameters ◽  
Transmission Coefficients ◽  
Transmission Properties

In the present paper, the material parameters of the isotropic relaxed micromorphic model derived for a specific metamaterial in a previous contribution are used to model its transmission properties. Specifically, the reflection and transmission coefficients at an interface between a homogeneous solid and the chosen metamaterial are analyzed by using both the relaxed micromorphic model and a direct FEM implementation of the detailed microstructure. The obtained results show excellent agreement between the transmission spectra derived via our enriched continuum model and those issued by the direct FEM simulation. Such excellent agreement validates the indirect measure of the material parameters and opens the way towards an efficient metastructural design.

Reflections, rays, and reverberations

1974 ◽  
Vol 64 (6) ◽  
pp. 1685-1696 ◽  
Author(s):  
B. L. N. Kennett
Keyword(s):  
Free Surface ◽  
Single Layer ◽  
Iterative Approach ◽  
Multilayered Media ◽  
Reflection And Transmission ◽  
Matrix Methods ◽  
Special Effects ◽  
Transmission Coefficients ◽  
Transmission Properties ◽  
Set Up

abstract The connection is established between conventional matrix methods for layered media and the reflection and transmission properties of a single layer. This interrelation is then used to set up an iterative approach to the calculation of reflection and transmission coefficients in multilayered media. This approach lends itself to a ray interpretation and allows estimates of errors involved in taking truncated partial ray expansions to be made. The special effects due to a free surface are also considered.

Precise Determination of Band Gap Naturally via Absorption/Reflectance/Transmission Spectra

2014 ◽  
Vol 509 ◽  
pp. 3-8 ◽  
Author(s):  
Ya Jie Liu ◽  
Ning Zhu
Keyword(s):  
Experimental Data ◽  
Band Gap ◽  
Material Property ◽  
Calculated Data ◽  
Precise Determination ◽  
Transmission Spectra ◽  
Spectroscopy Data ◽  
Reflection And Transmission ◽  
Experimental Spectroscopy

A set of nonlinear equations about the band gap and the indexnof material property with the absorptance, reflectance and transmittance were produced based on Tauc relation. Optimizing fitting the experimental spectroscopy data, such as absorption, reflection and transmission, the band gapand the indexnrelated to the material property could be obtained accurately and reliably. Meanwhile, the experimental data were used as more as possible, and the artificial errors at pre-determining the indexnwere avoided. The lowest correlation coefficient and the largest average relative error between the experimental and the calculated data are 0.9588 and 2.7% in all considered cases respectively. The best results show the band gap obtained from this method is more accurate, easier and faster than traditional extrapolation. Hence, this work would promote the precision and reliability for predicting the band gap and index of materials naturally.

scholarly journals Influence of Rugate Filters on the Spectral Manifestation of Tamm Plasmon Polaritons

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1282
Author(s):  
Victor Reshetnyak ◽  
Igor Pinkevych ◽  
Timothy Bunning ◽  
Dean Evans
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
External Medium ◽  
Metal Layer ◽  
Refractive Index Profile ◽  
Spectral Position ◽  
Index Profile ◽  
Reflection And Transmission ◽  
Rugate Filter ◽  
Plasmon Polaritons

This study theoretically investigated light reflection and transmission in a system composed of a thin metal layer (Ag) adjacent to a rugate filter (RF) having a harmonic refractive index profile. Narrow dips in reflectance and peaks in transmittance in the RF band gap were obtained due to the excitation of a Tamm plasmon polariton (TPP) at the Ag–RF interface. It is shown that the spectral position and magnitude of the TPP dips/peaks in the RF band gap depend on the harmonic profile parameters of the RF refractive index, the metal layer thickness, and the external medium refractive index. The obtained dependences for reflectance and transmittance allow selecting parameters of the system which can be optimized for various applications.

Extension of forward modeling phase-screen code in isotropic and anisotropic media up to critical angle

Geophysics ◽  
2007 ◽  
Vol 72 (5) ◽  
pp. SM107-SM114 ◽  
Author(s):  
James C. White ◽  
Richard W. Hobbs
Keyword(s):  
Critical Angle ◽  
Model Space ◽  
Anisotropic Media ◽  
Forward Modeling ◽  
Phase Screen ◽  
Computationally Efficient ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Phase Corrections ◽  
Converted Phases

The computationally efficient phase-screen forward modeling technique is extended to allow investigation of nonnormal raypaths. The code is developed to accommodate all diffracted and converted phases up to critical angle, building on a geometric construction method. The new approach relies upon prescanning the model space to assess the complexity of each screen. The propagating wavefields are then divided as a function of horizontal wavenumber, and each subset is transformed to the spatial domain separately, carrying with it angular information. This allows both locally accurate 3D phase corrections and Zoeppritz reflection and transmission coefficients to be applied. The phase-screen code is further developed to handle simple anisotropic media. During phase-screen modeling, propagation is undertaken in the wavenumber domain where exact expressions for anisotropic phase velocities are available. Traveltimes and amplitude effects from a range of anisotropic shales are computed and compared with previous published results.

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