Modeling Optical Materials at the Single Scatterer Level: The Transition from Homogeneous to Heterogeneous Materials

Abstract

Materials that contain distinct scatterers, for example, nanoparticles, with sizes exceeding 100 nm scatter light heavily and are heterogeneous. In contrast, the atomic or molecular scatterers in conventional optical materials form a homogeneous distribution on the scale of the wavelength. In this paper, the transition between homogeneous and heterogeneous materials is investigated. To this end, a procedure is introduced that allows for retrieving reliable refractive index values from full wave optical numerical simulations of the underlying multibody scattering problem. Using this procedure, it is shown that the concept of an effective refractive index breaks down on multiple levels as a material transitions out of the homogeneous regime. These findings allow for quantifying how novel dispersion‐engineered nanocomposites for bulk optical applications must be designed and show that Maxwell–Garnett‐type effective medium theories are accurate tools for the design of nanocomposites. The procedure can be readily generalized to other types of scatterers, including atoms and molecules and hence guide the design of different kinds of novel materials.

Measurement of the Optical Constants of Sand Samples Using Ellipsometry on Sand–Adhesive Composites

“…It has been shown recently that an effective medium approximation for n is a well-defined concept for scattering particles with a maximum diameter of only approximately λ/ 100. 23 In many cases, individual particles within the samples evaluated here are larger than this limit. While, in principle, it is possible to account for larger particles by using additional expansion terms in the description of scattering amplitude, 24 this is not done here.…”

Toward Maximally Electromagnetically Chiral Scatterers at Optical Frequencies

“…We are confident that, for this filling fraction, the chosen homogenization model can give a good estimation of the transmittance. 66,67 The thickness turns out to be a slab of 6.5 μm for the material composed of optimal helices for the design wavelength of 3 μm, 4.6 μm for the material composed of optimal helices obtained for the design wavelength of 800 nm, and 15.2 μm for a material composed of the tapered silver oxidized helices. The results for the performance of the three filters, obtained with this simple model, are shown in Figure 8 by the black squares.…”

Deep Learning Enabled Strategies for Modeling of Complex Aperiodic Plasmonic Metasurfaces of Arbitrary Size

“…9,10 For example, recent studies investigating the transition from homogeneous media to heterogeneous, random assemblies of larger structures revealed unexpected physical effects. 11 Moreover, designer metasurfaces with multiplexed functionalities like polarization diversity or achromatic responses typically consist of deterministic but complex arrangements of particles. 12−16 Despite their practical importance, large aperiodic arrangements of photonic nanostructures pose a challenging problem for computational methods.…”

“…Aperiodic, yet ordered metasurfaces have also been used for near-field shaping, for which optical interactions between plasmonic elements usually play a crucial role . Disorder can also play a role in the collective response of very large collections of nanostructures. , For example, recent studies investigating the transition from homogeneous media to heterogeneous, random assemblies of larger structures revealed unexpected physical effects . Moreover, designer metasurfaces with multiplexed functionalities like polarization diversity or achromatic responses typically consist of deterministic but complex arrangements of particles. − …”