Electromagnetic waves at grazing incidence onto a planar medium are analogous to zero energy quantum particles incident onto a potential well. In this limit waves are typically completely reflected. Here we explore dielectric profiles supporting optical analogues of `half-bound states', allowing for zero reflection at grazing incidence. To obtain these profiles we use two different theoretical approaches: supersymmetric quantum mechanics, and direct inversion of the Helmholtz equation.
Grazing incidence waves incident onto a surface will almost always be completely reflected. Here, we focus on removing reflection at grazing incidence, adopting the factorisation method from quantum mechanics and applying it to the Helmholtz equation that governs a single electromagnetic polarisation. We show that there are two approaches, the first is to require real dielectric profiles that support a half-bound state at grazing incidence. The second is to allow non-Hermitian dielectric profiles that exhibit PT symmetry, supporting waves with constant intensity throughout the profile.
The theory of both transmission and grazing incidence Mössbauer spectroscopy is re-analyzed. Starting with the nuclear susceptibility tensor a common concise first order perturbation formulation is given by introducing the forward scattering amplitude into an anisotropic optical scheme. Formulae of Blume and Kistner as well as those of Andreeva are re-derived for the forward scattering and grazing incidence geometries, respectively. Limitations of several previously intuitively introduced approximations are pointed out. The grazing incidence integral propagation matrices are written in a form …
Grazing incidence interferometry has been applied to rough planar and cylindrical surfaces. As suitable beam splitters diffractive optical phase elements are quite common because these allow for the same test sensitivity for all surface points. But a rotational-symmetric convex aspheric has two curvatures which reduces the measurable region to a meridian through the vortex of the aspheric, which is in contrast to cylindrical surfaces having a one-dimensional curvature which allows the test of the whole surface in gracing incidence. The meridional limitation for rotational-symmetric aspherics n…
Probing laser-driven surface and subsurface dynamics via grazing-incidence XFEL scattering and diffraction
European X-ray Free-Electron Laser Facility（欧洲X射线自由电子激光设施）；Department Physik, Universität Siegen（锡根大学物理系）；Helmholtz-Zentrum Dresden-Rossendorf（德累斯顿-罗斯多夫亥姆霍兹中心）；Department of Physics and Research Center OPTIMAS, RPTU University Kaiserslautern–Landau（凯泽斯劳滕-兰道理科大学物理系及OPTIMAS研究中心）
The diffraction of electromagnetic waves at the surface periodic structures accompanied by strong anomalous effects in different diffraction orders is considered in great detail for high-contrast interfaces. We restrict our discussion to the TM polarization of the incident wave (the magnetic field is orthogonal to the plane of incidence) and the simplest geometry when the plane of incidence is orthogonal to the grating grooves. The most attention is focused on the strong maxima and minima of the energy flux density accompanying specific grazing propagation of some diffraction order. Relation t…
We investigate electromagnetic scattering from nanoscale wires and reveal for the first time, the emergence of a family of exotic resonances, or enhanced fields, for source waves close to grazing incidence. These grazing resonances can have a much higher Q factor, broader bandwidth, and are much less susceptible to material losses than the well known surface plasmon resonances found in metal nanowires. Contrary to surface plasmon resonances however, these grazing resonances can be excited in both dielectric and metallic nanowires and are insensitive to the polarization state of the incident wa…
Grazing-angle scattering (GAS) is a type of Bragg scattering of waves in slanted non-uniform periodic gratings, when the diffracted order satisfying the Bragg condition propagates at a grazing angle with respect to the boundaries of a slab-like grating. Rigorous analysis of GAS of bulk TE electromagnetic waves is undertaken in holographic gratings by means of the enhanced T-matrix algorithm. A comparison of the rigorous and the previously developed approximate theories of GAS is carried out. A complex pattern of numerous previously unknown resonances is discovered and analysed in detail for gr…
Grazing incidence x-ray scattering provides nanostructural information for thin film samples, but single images generally do not provide information on film thickness or the full complex index of refraction. Additionally, for thin films that possess stratification of scatterers vertically within a sample, it can be difficult to determine where those scatterers are positioned. We present an in-situ method to extract film thickness, the index of refraction, and depth information using scattering images taken across a range of incident angles. The underlying theory is presented, and we validate t…
We study the interaction of electromagnetic (EM) radiation with single-layer graphene and a stack of parallel graphene sheets at arbitrary angles of incidence. It is found that the behavior is qualitatively different for transverse magnetic (or p-polarized) and transverse electric (or s-polarized) waves. In particular, the absorbance of single-layer graphene attains minimum (maximum) for p (s) polarization, at the angle of total internal reflection when the light comes from a medium with a higher dielectric constant. In the case of equal dielectric constants of the media above and beneath grap…
We derive the transmission coefficient, $T(ω)$, for grazing incidence of crystals with spatial dispersion accounting for the excitation of multiple modes with different wave vectors ${\bf k}$ for a given frequency $ω$. The generalization of the Fresnel formulas contains the refraction indices of these modes as determined by the dielectric function $ε(ω,{\bf k})$. Near frequencies $ω_e$, where the group velocity vanishes, $T(ω)$ depends also on an additional parameter determined by the crystal microstructure. The transmission $T$ is significantly suppressed, if one of the excited modes is decay…
