The area of nanophotonics has been the focus of researchers recently due to its high
potential to overcome the limitations of scaling in electronic devices. One of the most
popular devices in this field is the metasurface. A metasurface consists of a periodic
or aperiodic array of spaced units called ’meta-atoms’, where the interaction between
these neighboring elements provide unprecedented properties that cannot be obtained
using a a regular array of antennas. By tuning the shape and structure of the meta-atoms, electromagnetic wave interaction with the metasurface can be manipulated to
achieve a plethora of response characteristics.
For active applications that require tunability of the response, a passive metasurface cannot be used to adapt to the varying operating conditions. Tunability of
metasurfaces can then be achieved by using phase-changing materials. This type of
materials can attain different optical properties by applying external stimulus such
as heat, electric current, or laser pulses. The change in the optical properties would
be beneficial for applications requiring reconfigurability or adaptation.
In this thesis, I demonstrate the employment of volatile (Vanadium Dioxide) and
non-volatile (Germanium Antimony Telluride) examples of phase-change materials
to design reconfigurable metasurfaces operating at different bands in the infrared
regime. I show metallic and dielectric-based structures that employ volatile and non-volatile phase-change materials, as well as apply physics such as plasmonics and bound
states in the continuum to design and optimize metasurface structures for energy and
biosensing applications. / Thesis / Doctor of Philosophy (PhD) / This thesis proposes methods to design and optimize reconfigurable and adaptive
metasurfaces for energy harvesting, radiative cooling, and biosensing applications in
the infrared range. The concept of phase-change metasurfaces is highlighted where a
phase-change material (PCM) is employed to provide the tunable response. The properties of the PCM can be modified using several excitation methods such as thermal,
electric, and laser excitation. The details of material selection, geometry configuration, as well as optimization procedures are demonstrated. Target applications
for the study is harvesting from Earth’s ambient radiation around 10.6µm, adaptive
cooling of spacecraft in the mid-infrared band 2.5 − 25µm, and trace biomarkers detection in the amide-I and amide-II bands (5.5−6.9µm). Full-wave numerical analysis
was conducted using COMSOL Multiphysics software. Optimization was carried out
using global optimization techniques implemented using Matlab and Python. The
results show innovative designs for switchable absorbers, new approach for modeling
of phase-change metasurfaces using deep learning, and employment of the physics
of bound states in the continuum for the first time to implement a robust biosensing device. The results of this thesis would help advance the field of reconfigurable
nanophotonics and related integrated applications.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28974 |
| Date | January 2023 |
| Creators | Negm, Ayman |
| Contributors | Bakr, Mohamed, Howlader, Matiar, Ali, Shirook, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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