Satellite peaks in the scattering of light from the two-dimensional randomly rough surface of a dielectric film on a planar metal surface (original) (raw)
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Optics Communications, 1997
The reflected field scattered from a thin metallic film with a shallow rough random surface bounded by two semi-infinite dissimilar optical media is calculated. The mode1 assumes that all media are homogeneous, isotropic, non-magnetic, linear and may be characterized by a frequency dependent complex dielectric function. The Rayleigh hypothesis is used to obtain an independent integral equation relating the amplitudes of the reflected fields to the incident wave. This treatment is valid for both TM(p) or TE(s) polarizations. Numerical results are obtained by assuming a Gaussian roughness spectrum for the random rough surface and the formalism is applied to simulate the scattering in the ATR-Kretschmann configuration, allowing the excitation of surface plasmons (SP), prism-metal-air.
Light scattering from surfaces with a single dielectric overlayer*
Journal of the Optical Society of America, 1976
First-order perturbation theory and a nonorthogonal coordinate transformation are used to calculate light scattering from rough metallic surfaces having a dielectric overlayer. The theory considers arbitrary polarization, incident intensity profile, and angle of incidence, and it is valid for complex values of the dielectric constants of the metal e and dielectric overlayer co. The frequency range of interest is such that Re(e) < 0. The results are applied to cases of periodic and random roughness where the dielectric overlayer replicates the substrate profile. Comparison to experiment is made in the case of periodic roughness, and numerical results are given in both cases.
Light scattering from an amplifying medium bounded by a randomly rough surface: A numerical study
Physical Review B, 2001
We study by numerical simulations the scattering of s-polarized light from a rough dielectric film deposited on the planar surface of a semi-infinite perfect conductor. The dielectric film is allowed to be either active or passive, situations that we model by assigning negative and positive values, respectively, to the imaginary part ε2 of the dielectric constant of the film. We study the reflectance R and the total scattered energy U for the system as functions of both ε2 and the angle of incidence of the light. Furthermore, the positions and widths of the enhanced backscattering and satellite peaks are discussed. It is found that these peaks become narrower and higher when the amplification of the system is increased, and that their widths scale linearly with ε2. The positions of the backscattering peaks are found to be independent of ε2, while we find a weak dependence on this quantity in the positions of the satellite peaks.
Theory of light scattering from a rough surface with an inhomogeneous dielectric permittivity
Physical review B, 1984
First-order perturbation theory is applied to calculate scattering of a plane wave from a planebounded, semi-infinite medium where the boundary surface has a roughness perturbation and the scattering medium consists of an isotropic perturbation of the dielectric permittivity. The dielectric perturbation is assumed to fluctuate randomly in the plane parallel to the surface and decay exponentially with depth into the surface. Both the roughness and dielectric permittivity perturbations, which are treated as random variables, can independently cause scattering, and there is generally interference between the two scattered fields. The scattered fields generally depend on the autocovariance functions of the surface roughness and dielectric fluctuations and on the crosscorrelation properties between them. For this reason, the polarization ratio of the pand spolarized scattered light fields depends on the autocovariance and cross-correlation statistical properties. This result is unlike the calculation of scattered fields caused by roughness or dielectric perturbations alone, since in this case the polarization ratios of the scattered fields do not depend on the statistical properties of the perturbation. The numerical results of this work are consistent with experimental measurements where the polarization ratio of light scattered from nominally identical silver films varies widely from surface to surface.
Resonance effects in multiple light scattering from statistically rough metallic surfaces
Physical Review B, 1992
Multiple scattering of light from one-dimensional random rough metallic surfaces is numerically studied by means of a Monte Carlo simulation method based on the extinction-theorem boundary conditions. Angular and integrated distributions of the mean scattered intensity are computed for several values of the angle of incidence, state of polarization, surface statistical parameters, and dielectric permittivity. Two main regimes are addressed, depending on whether the surface correlation length T is larger or smaller than the wavelength A, . In the first case, we observe enhanced backscattering both for s and p waves, whereas in the latter situation there exist substantial absorption effects under p polarization, linked to the excitation of surface polaritons. In addition, calculations are made of field enhancements on the surface, owing either to surface-polariton excitation in the small-correlation-length case (T & A, ), or to multiple scattering and generation of other kinds of surface wave in the large-correlation-length case (T & A, ).
Light scattering from random rough dielectric surfaces
Journal of the Optical Society of America A, 1991
A theoretical and numerical study is made of the scattering of light and other electromagnetic waves from rough surfaces separating vacuum from a dielectric. The extinction theorem, both above and below the surface, is used to obtain the boundary values of the field and its normal derivative. Then we calculate the angular distribution of the ensemble average of intensity of the reflected and transmitted fields. The scattering equations are solved numerically by generating one-dimensional surface profiles through a Monte Carlo method. The effect of roughness a-and correlation distance T on the aforementioned angular distribution, as well as on the reflectance, is analyzed. Enhanced backscattering and new transmission effects are observed, also depending on the permittivity. The ratio o/T is large in all cases studied, and thus no analytical approximation, such as the Kirchhoff approximation (KA) and small perturbation methods, could a priori be expected to hold. We find, however, that the range of validity of the KA can be much broader than that previously found in perfect conductors.
The scattering of electromagnetic waves from a randomly rough surface was principally studied when the rough surface separates a dielectric volume with an infinite thickness from vacuum or when the surface is a weakly rough two-dimensional random metal surface. The theoretical studies of scattering from rough metal surfaces has been described by the sum of the contribution from all ladder diagrams in a diagrammatic perturbation theory approach and the enhanced backscattering is included through the addition of the contribution from all maximally-crossed diagrams to that of the ladder diagrams. But when we consider a film with two randomly rough surfaces, new phenom- ena (1) can be observed: the well-defined peak in the retro-reflection direction and satellite peaks due to the multiple scattered waves in the dielectric layer. These phenomena have been predicted by a perturbative calculation in the case of one-dimensional surfaces (2). The theoretical method to calculate the perturbat...
Light scattering by randomly rough isotropic dielectric surfaces
Journal of Modern …, 2000
An experimental investigation of the angular distribution of the light scattered by randomly rough, two-dimensional, isotropic dielectric surfaces is presented. T he surfaces, whose pro® les constitute good approximations to Gaussian random processes with Gaussian correlation functions, are fabricated in a photoresist and characterized by means of a mechanical pro® lometer. T he substrates employed in the fabrication of the samples consist of thick parallel plates of ® lter glass that absorb the incident light and whose refractive index is close to that of the photoresist. T his allows us to approximate experimentally a situation in which the light is scattered by a randomly rough interface between two semi-in® nite dielectric media, illuminated from the air side. T he results display features that can be attributed to multiple scattering. In particular, signi® cant amounts of cross-polarized scattered light, as well as an enhanced backscattering peak, were observed in the scattering measurements.
The scattering of electromagnetic waves from a randomly rough 2D metallic surface
Optics Communications, 1994
By a computer simulation approach we study the scattering of a finite beam of p-polarized light from very rough two-dimensional metallic surfaces. Enhanced backscattering is observed. It is found that the approximation of a metal surface by a perfectly conducting surface in the visible region of the optical spectrum is less good for in-plane, co-polarized and out-of-plane, crossedpolarized scattering than it is for in-plane, crossed-polarized and out-of-plane, co-polarized scattering.
Scattering of light from a two-layer system with a rough surface
Journal of The Optical Society of America A-optics Image Science and Vision, 1999
The scattered light from a two-layer system with a shallow, random, one-dimensional rough surface bounded by semi-infinite dissimilar optical media is calculated. The systems is composed of metallic and weak absorbent dielectric films between glass and vacuum. The dielectric constant and the thickness of the dielectric film are chosen in such a way that in the absence of roughness the system supports eight transverse magnetic (TM) guided modes, whose wave numbers are q 1 (TM) (), q 2 (TM) (), . . . , q 8 (TM) (), or nine transverse electric (TE) guided modes, whose wave numbers are q 1 (TE) (), q 2 (TE) (), . . . , q 9 (TE) (), at the wavelength . The Rayleigh hypothesis is used to obtain an integral equation relating the amplitudes of the reflected fields to the incident wave. The scattering integral is solved both by perturbation and numerically. Results are obtained by assuming a Gaussian roughness spectrum for the surface, and the formalism is applied to simulate the scattering from the system in the attenuated total reflection configuration, allowing the excitation of guided waves. The angular dependence of the scattering shows four peaks, in addition to the backscattering effect. The angular positions of these peaks are given by (2/)n 1 sin k (t) ϭ Ϯq k (t) , with k ϭ 7, 8 when t ϭ ͕ p, TM͖ or k ϭ 8, 9, when t ϭ ͕s, TE͖; they are also independent of the angle of incidence and are due to single-scattering effects.