A Volume Integral Equation (VIE) Algorithm to Model the Non-local Electromagnetic Response of Deep Nanometer Scatterers
This PhD research essentially focuses on the development of computational algorithms investigating light-matter interaction at a nanometric scale. The light-nanoantenna interaction has attracted a considerable attention, particularly after entry into deep-nanometer regime; however, to our best knowledge, only a handful computationally related efforts have been made. This extremely small scale inevitably introduces quantum mechanical effects, such as quantum tunnelling or the excitation of longitudinal plasmons, thus governing the nanoantenna optical response. In contrast to the conventionally treated local response theory approximation, the implemented algorithm relies on the hydrodynamic model, taking nonlocal material parameter and quantum mechanical effects into account. In addition, a specific planar multilayered environment will be included in the algorithm, surrounding the structure-under-study. Based on the algorithmic implementation, the research aims at the analysis and design of innovative sub-nanometer and nanometer antennas. Notably, practical generic nanoantenna systems are associated with the striking feature of confining enhanced electromagnetic fields and have been already successfully proposed and realised for a wide range of applications. For example, an optoelectronics photodiode response can be considerably improved by on-chip integrated aperture or bar-shaped nanoantennas. Moreover, the surface Raman spectroscopy and near field optical microscopy have been enhanced by direct correspondence of nanoshell and nanosphere structures. The field of information and communication technology may become another potential nanoantenna target in terms of storing, processing and transmitting information. In order to evaluate the algorithm’s performance, this research largely employs commercially available numerical electromagnetic tools, such as COMSOL Multiphysics or CST MICROWAVE STUDIO. Furthermore, an experimental validation of accurately engineered nanoantenna topologies is conducted by fabricating selected designs and measuring their corresponding optical features, namely the extinction cross section and near field intensity enhancement.