Multi-material design optimization of optical properties of particulate products by discrete dipole approximation and sequential global programming

Abstract

The optimal design of nanoparticles with respect to their optical properties is one of the main foci within nanoparticle technology. In this contribution, we suggest a new design optimization method in the framework of which the discrete dipole approximation (DDA) is used to approximate the solution of Maxwell’s equation in time-harmonic form. In the core of the optimization method, each dipole is repeatedly assigned a material property from a given material catalog until a local minimum for the chosen design objective is obtained. The design updates are computed using a separable model of the optimization objective, which can be solved to global optimality, giving rise to a sequential global optimization (SGP) algorithm. We suggest different types of separable models, among them exact separable models as well as tight approximations of the latter which are numerically tractable. The application of the DDA method in the framework of structural design methods widens the spectrum of numerically tractable layout problems in optical applications as, compared to finite element based approaches, significantly more complex design spaces can be investigated.

An Investigation on the Use of Au@SiO2@Au Nanomatryoshkas as Gap-Enhanced Raman Tags

“…For particles of these sizes, it has been reported that a quantum mechanical description agrees with classical approaches [27,34]. Comparable computational methods like Finite Element Method (FEM) and Finite Difference Time Domain (FDTD) do not scale well in time and accuracy for differently sized systems [35][36][37]. A comparison of our DDA results with the multilayer Mie theory by Yang et al [32] can be found in Figure 1, and the DDA and Mie calculations align almost perfectly.…”

Targeted color design of silver–gold alloy nanoparticles

“…43 Dropping this assumption and considering anisotropic particles or even distributions thereof, impedes a full analysis of the admissible color range, but still allows for optimization of particle structure with respect to color. 44,45 However, such settings require specialized optimization techniques. 46 Moving forward, our approach involves working with experimentally produced NP suspensions with variations in size and chemical composition.…”

Optimizing Color of Particulate Products

“…the discrete dipole approximation (DDA). The optimization of particle designs in DDA has been considered in [17] for a small number of incoming wavelengths. However, as such methods have vastly higher computational cost and our settings require optimization with respect to infinitely many wavelengths, we focus on Mie particles in this contribution, to allow for a more detailed analysis of the optimization problems.…”