STUDY OF SCATTERING BY LINEAR CHAIN OF CYLINDRICAL NANOPARTICLES

Abstract

Optical nanoantennas for visible and infrared radiation can strongly enhance the interaction of light nanoscale matter by their ability to efficiently link propagating and spatially localized optical fields. This ability unlocks an enormous potential for applications ranging from nanoscale optical microscopy and spectroscopy over solar energy conversion, integrated optical nanocircuitry, opto-electronics and density of states engineering to ultra-sensing as well as enhancement of optical nonlinearities. Thus the useful results prompt us to implement a more systematic and further exploration on nanoantennas of some specific configuration of interest. This dissertation is the study of various works in the field of optical nanoantennas, thereafter design and analyze optical nanoantennas. The focus of this thesis is to put on the investigations of single and multiple dielectric nanoparticles for their near-field and far-field radiation properties. In particular, we elaborately design and carefully analyze such structures to perform their functions as the nanoantennas operating in the optical regime. The Generalized Kerker’s conditions are studied in detail to understand scattering of light by nanoparticles of various shapes and sizes. A study on the accurate behavior of single dielectric nanoparticles is done as to how the scattering of incident field by the nanoparticle enables it to exhibit unidirectional scattering at wavelengths where first and second Generalized Kerker’s conditions are fulfilled. An appropriate numerical approach with the use of FEM is developed for a more effective calculation of nanoantennas covering the broad frequency range including visible and infrared region. Comprehensive investigations are carried out and presented in detail on various factors which have significant impacts on the nanoantenna’s performance in the optical region. The software used is COMSOL MULTIPHYSICS whose operation is dependent on the finite element analysis method. The software calculates scattering cross section, far-field pattern and directivity for the optical nanoantenna MATLAB is also used for mathematical computation as and when required.