Finite element modeling of the radiative properties of Morpho butterfly wing scales.

With the aim of furthering the explanation of iridescence in Morpho butterflies, we developed an optical model based on the finite-element (FE) method, taking more accurately into account the exact morphology of the wing, origin of iridescence. We modeled the photonic structure of a basal scale of the Morpho rhetenor wing as a three-dimensional object, infinite in one direction, with a shape copied from a TEM image, and made out of a slightly absorbing dielectric material. Periodic boundary conditions were used in the FE method to model the wing periodic structure and perfectly matched layers permitted the free-space scattering computation.

Model of light scattering that includes polarization effects by multilayered media.

We present a model for calculating the angular distribution of light, including polarization effects from multilayered inhomogeneous media, with an index of refraction mismatch between layers. The model is based on the resolution of the radiative transfer equation by the discrete ordinate method. Comparisons with previous simpler models and examples of simulations are presented.

Optical properties of Ag -TiO 2 nanocermet films prepared by cosputtering and multilayer deposition techniques.

Ag -TiO2 nanocermet thin films, deposited for optical filtering applications by two sputtering techniques, codeposition and multilayer deposition, exhibit surface plasmon absorption in the spectral range 450 -500 nm. The cosputtering technique induces a columnar growth, whereas multilayer deposition produces a more-random distribution of silver inclusions. Both films have large, flat silver grains at the air -cermet interface.

Optical Properties of Ag-TiO(2) Nanocermet Films Prepared by Cosputtering and Multilayer Deposition Techniques.

Ag-TiO(2) nanocermet thin films, deposited for optical filtering applications by two sputtering techniques, codeposition and multilayer deposition, exhibit surface plasmon absorption in the spectral range 450-500 nm. The cosputtering technique induces a columnar growth, whereas multilayer deposition produces a more-random distribution of silver inclusions. Both films have large, flat silver grains at the air-cermet interface.

Effects of pulsed low frequency electromagnetic fields on water using photoluminescence spectroscopy: role of bubble/water interface.

The effects of a pulsed low frequency electromagnetic field were investigated on photoluminescence of well characterized water and prepared under controlled conditions (container, atmospheric, electromagnetic, and acoustic environments). When reference water samples were excited at 260 nm, two wide emission bands centered at 345 nm (3.6 eV) and 425 nm (2.

Effects of pulsed low-frequency electromagnetic fields on water characterized by light scattering techniques: role of bubbles.

Well-characterized purified water was exposed for 6 h to pulsed low-frequency weak electromagnetic fields. After various time periods, nondegassed and degassed water samples were analyzed by static light scattering. Just after electromagnetic exposure (day 0), a reduction of over 20% in the maximum light scattering intensity at 488 nm wavelength in both nondegassed and degassed samples was observed.

Comparison of the auxiliary function method and the discrete-ordinate method for solving the radiative transfer equation for light scattering.

Two methods for solving the radiative transfer equation are compared with the aim of computing the angular distribution of the light scattered by a heterogeneous scattering medium composed of a single flat layer or a multilayer. The first method [auxiliary function method (AFM)], recently developed, uses an auxiliary function and leads to an exact solution; the second [discrete-ordinate method (DOM)] is based on the channel concept and needs an angular discretization. The comparison is applied to two different media presenting two typical and extreme scattering behaviors: Rayleigh and Mie scattering with smooth or very anisotropic phase functions, respectively.

Absorption in multiple-scattering systems of coated spheres.

We derive formulas for rigorous transfer matrix calculations of absorption in multiple-coherent-scattering systems in which the scatterers are multiply coated spheres (not necessarily concentric). Any of the spherical coatings, cores, or host media may be composed of absorbing materials. For a nonabsorbing host media, the total absorption may be deduced from overall energy conservation.

Effective media equivalent to an asymmetric multilayer and to a rough interface.

A computer fitting program is used to show that not only a symmetric but also an asymmetric multilayer, composed of a periodic structure with small thickness irregularity or with slightly rough interfaces, can be equivalent to an anisotropic single layer within a good approximation. It is also shown that an interface layer equivalent to a rough interface does not exist, in spite of the fact that such an assumption has widely been used.

Effective medium equivalent to a symmetric multilayer at oblique incidence.

It is shown that a multilayer with repeated symmetric unit structure is equivalent to a homogeneous and optically biaxial medium for obliquely incident light, the three principal axes being normal to the plane of incidence, normal to the film plane, and normal to the other two. Unit thickness dependence and incident angle dependence of the dielectric tensor and the effective thickness are calculated using exact formulas. It is found that, at small unit structure thickness, the equivalent medium is almost uniaxial, the optical axis being normal to the film, and the effective thickness is very close to the mechanical one.