Confinement of photons, electrons and magnetism in nano/meta-materials

点击翻译按钮获取中文摘要

This PhD project studies the linear and nonlinear (colour-changing) optical properties of nanoparticles and artificially nanostructured materials and surfaces.Nanostructuring materials and surfaces (creating an artificial structure, e.g. an array of geometrical shapes, on the nanoscale) strongly affects their optical properties. Thus, it is possible to design and manufacture nanosurfaces with desired properties for specific applications. Often, the nanosurfaces are made of plasmonic metals. These metals (e.g. gold, silver, aluminium, ...) host plasmons (coherent oscillations of electrons on the surface of these metals) and interact strongly with light.Plasmonic nanoparticles can be used to study new optical phenomena, such as optical activity in hyper-Rayleigh scattering. In hyper-Rayleigh scattering, light scattered from the nanoparticles has double the frequency of the incident light (e.g. if red light is incident on the nanoparticles, the scattered light is blue). Optical activity means that the amount of scattered light depends on the circular polarisation ("twist") of the incident light. The effect has potential use in sensitive characterisation of molecules used in pharmaceuticals. In this project, we study hyper-Rayleigh scattering in suspensions of plasmonic nanoparticles with various geometries to gain better understanding of the effect, which is essential for successful future applications. The project might involve attaching chemical molecules to plasmonic nanoparticles with the aim of increasing their optical response.Plasmonic nanosurfaces studied as part of this project have potential applications in increasing the accuracy of optical characterisation of molecules, in detecting air pollution and in other areas. The aim of our research is to characterise and optimise the performance of these structures.We also plan to design nanosurfaces made of magnetic materials with the aim of tuning the optical properties of the nanostructures with magnetic field.Mostly optical methods are used to study the nanoparticles and nanostructures. These include well-established methods, such as optical microscopy, as well as novel optical experiments, which we assemble in our lab. The exact experimental configuration depends on the studied samples but, generally, we use ultrashort-pulse lasers as light sources and design our experiments in a way to maximise the sensitivity of detection of the nonlinear properties of the samples.