Geometry Dependent Optimal Bounds of Absorption and Scattering Cross-section for Small Nanoparticles

Sammanfattning: Light-matter interaction in particles of subwavelength size mostly depends on the size, shape, composition of the particles and relies on the properties of incident light. Henceforth, resonant behavior of light can be effectively controlled by changing the aforesaid geometrical parameters. The aim of this study is to investigate the effect of size, shape, and material property dependency on the optimal bounds of scattering and absorption cross-section of nanoparticles. Mie theory is used here to solve Maxwell’s equations of light scattering from nanoparticles of different shape to calculate both scattering and absorption cross-sections of silicon and gold nanoparticles. In this work, numerical analysis based on Finite-Difference Time-Domain (FDTD) method is performed to study the optical properties of different size and shapes of silicon and gold nanoparticles such as sphere, pyramid, ring, and cubical structures. In particular, this study reveals how the resonant behaviour (magnitude and peak position) of light varies in accordance with the change in size, shape and material of a specific particle structured in nanoscale. In conclusion, we can quantify the efficiency of a small absorbing or scattering medium and propose structures suitable for implementation in inverse design applications.