Optically-Induced Magnetic Response in All-Dielectric Nanodisk Composite Structures
Date
2017
Authors
Chong, Katie Eve
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Abstract
Optical technologies developed throughout history have been
exploiting the electric response in matters in order to control
light. However, little has been explored for the magnetic
response in matter at optical frequencies due to the lack of
magnetic materials in this spectral region. Recently, specially
engineered materials, namely metamaterials, have been developed
to exploit the magnetic responses in matter for light
manipulation. In particular, researchers have made use of the
optically-induced magnetic responses (OIMRs) generated in
metallic nanostructures to achieve optical effects not seen in
nature. Such magnetic responses serve as a second channel to
control light, providing an alternative and an addition to the
electric responses and leading to novel observations and
innovative ideas for light manipulation. This creates many
opportunities for the development of the next generation
nano-optics and nanophotonic devices.
Dielectric nanostructures have recently been discovered to also
support OIMR, which is useful for applications requiring low loss
and simpler fabrication procedures, such as wavefront control and
robust nanoscale sensing. In this thesis, I present the study of
OIMR in several all-dielectric systems based on silicon
nanodisks, namely single, clusters and regular arrays of
nanodisks. The study of these systems provides knowledge for and
insight into harnessing the OIMRs in dielectric nanostructures
for future applications.
Chapter 1 provides a comprehensive introduction to OIMR by
presenting a historic overview of the topic and the basic
concepts involved for high-index dielectric particles. This is
followed by a description of the pioneer works on OIMR in
dielectric spherical nanoparticles, including the Mie theory and
its recent experimental verification. The similarities and
differences between the properties of plasmonic and dielectric
nanostructures in the context of metamaterials are also described
and explained. Finally, the motivation and scope of the thesis
is summarized.
Chapter 2 describes the experimental methods used that are common
to all works presented in this thesis, including the fabrication
of silicon nanodisk structures and the linear optical
characterization techniques.
Chapter 3 presents the fundamental of OIMR in single silicon
nanodisk structures, including a theoretical analysis and
experimental observation of various resonant modes of single
silicon nanodisks, as well as the numerical and experimental
results of the Fano resonances observed in the more complex
structures of single heptamer oligomers.
Chapter 4 focuses on manipulating the OIMR in combination with
the electric response to create Huygens' metasurfaces based on
silicon nanodisk arrays. Two highly-efficient functional
metadevices with polarization independence based on the Huygens'
metasurface system are presented, namely a Gaussian-to-vortex
beam shaper and a holographic phase plate.
Chapter 5 explores the cross-disciplinary area of sensing using
silicon nanodisk arrays with OIMRs, including refractive index
sensing using Fano resonances and biosensing using the dipolar
magnetic resonances where a new detection limit for the
Streptavidin protein was achieved.
Chatper 6 concludes the thesis and provides an outlook to the
research works that can be extended from the results in this
thesis.
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nanophotonics, metasurfaces, dielectric metasurfaces, optically-induced magnetic response, Fano resonance, nanostructures, nanodisks, silicon nanostructures, magnetic response
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