Diffraction gratings and solar selective thin film absorbers: An experimental study

Golomb, M.

doi:10.1016/0030-4018(78)90360-7

Cited by 10 publications

(2 citation statements)

References 3 publications

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“…The traditional solution to this problem has been to place one or more anti-reflecting films on top of the interface . However, in recent years interest has been growing in another possibility-that of roughening or texturing the interface in such a fashion as to yield a reduced reflectance [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] . These studies have shown that the effects of roughening an interface are often similar to those obtained if a graded refractive index film is deposited on the interface .…”

Section: Introductionmentioning

confidence: 99%

Diffraction Gratings in the Quasi-static Limit

Bell

Derrick

McPhedran

1982

Optica Acta: International Journal of Optics

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For gratings having an arbitrary symmetric profile, we prove that when the period becomes much finer than the wavelength the grating becomes equivalent to a graded uniaxial layer . We show for one polarization that this quasi-static equivalence holds when the ratio of wavelength to grating period exceeds 40 . We also present a simple physical model which explains the anisotropic nature of the equivalent layer . We take the case of a finely-textured copper surface, and show that it can be a good selective absorber for polarized light, but that its performance in unpolarized' light is much less satisfactory .

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Section: Introductionmentioning

confidence: 99%

Diffraction Gratings in the Quasi-static Limit

Bell

Derrick

McPhedran

1982

Optica Acta: International Journal of Optics

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“…The absorption of waves (hydrodynamic waves, optical or other electromagnetic waves, acoustic waves in fluids, elastic waves in solids) is an ongoing major research topic. Four applicative subtopics illustrate this importance: i) harvesting of energy [64], particularly that coming from solar irradiation [89,45,22,93,71,35,47,88,96,68,73,82,92,10,34,103,26,66,54,56], ii) breaking (i.e., dissipating the energy of) water waves in rising oceans to protect harbors, coastal shores and constructions [58,30,75,94,76,103,2,104,65], iii) sound level reduction in increasingly noisy open environments and reverberation reduction in enclosures [23,6,63,5,7,38,67,95,46,40,39,42,53,44,8,49], iv) mitigatio...…”

Section: Introductionmentioning

confidence: 99%

Incorporation of macroscopic heterogeneity within a porous layer to enhance its acoustic absorptance

Wirgin

2018

Preprint

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We seek the response, in particular the spectral absorptance, of a rigidly-backed periodically-(in one horizontal direction) inhomogeneous layer composed of alternating rigid and macroscopically-homogeneous porous portions, submitted to an airborne acoustic plane body wave. The rigorous theory of this problem is given and the means by which the latter can be numerically solved are outlined. At low frequencies, a suitable approximation derives from one linear equation in one unknown. This approximate solution is shown to be equivalent to that of the problem of the same wave incident on a homogeneous, isotropic layer. The thickness h of this layer is identical to that of the inhomogeneous layer, the effective complex body wave velocity therein is identical to that of the porous portion of the inhomogeneous layer, but the complex effective mass density, whose expression is given in explicit algebraic form, is that of the reference homogeneous macroscopically-porous layer divided by the filling factor (fraction of porous material to the total material in one grating period). This difference of density is the reason why it is possible for the lowest-frequency absorptance peak to be higher than that of a reference layer. Also, it is shown how to augment the height of this peak so that it attains unity (i.e., total absorption) and how to shift it to lower frequencies, as is required in certain applications.

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