Metamaterials with resonant silicon nanoparticles for perfect mirrors

Investigation, design, and realisation

verfasst von: Mariia Matiushechkina
betreut von: Michele Heurs
Abstract: A metasurface is a single-layer artificial structure composed of specially arranged particles, which can be configured in size and shape to alter the metasurface’s interaction with the incident electromagnetic field. The application potential of metasurfaces is vast, as they offer flexibility in tuning their properties while maintaining an ultra-thin, lightweight coating structure optimised for specific functionalities. Among the diverse potential applications, special attention is directed towards the field of gravitational wave physics. Gravitational wave detectors, which function as advanced Michelson interferometers, consist of highly sensitive test masses covered with reflective coatings. The next generation of detectors demands novel coating designs capable of operating at cryogenic temperatures and exhibiting minimal thermal noise. One potential alternative is a metasurface coating design that can be tailored to satisfy essential requirements. This thesis focuses on the development of highly reflective metasurfaces and their experimental realisation. In the framework of the investigation, the target wavelengths for the high-reflectivity effect are selected to be 1064nm and 1550 nm, as these are relevant to nextgeneration gravitational wave observatories. The thesis presents an analysis and description of the phenomenon of light reflection from a metasurface, originating from the resonant response of its constituent nanoparticles. Possible designs incorporating spherical and cylindrical shapes of nanoparticles are modelled and characterised through numerical simulations (Comsol Multiphysics) and a semi-analytical multipole approach. Structural optimisation, the integration of protective and supporting mediums, and their influence on performance and fabrication imperfections are considered, simulated and discussed throughout the research. On the practical side, the prototypes of the metasurface structures, composed of polycrystalline silicon cylinders on a sapphire substrate, have been realised at the selected wavelengths. The realisation process entails evaluating dimensional parameters based on the measured material properties and using a fabrication process with electron beam lithography. The characterisation of the fabricated metasurfaces demonstrates good agreement with the numerically predicted behaviour. While the primary objective is to achieve near-perfect reflectivity across all configurations, the developed analytical and numerical methods, along with the fabrication procedure, are also applicable to the development of metasurfaces with partial reflectivity or full transmissivity. These theoretical and experimental achievements in metasurface realisation have the prospect of further development and implementation in the field of gravitational wave physics and other optical experiments.
Organisationseinheit(en): QuantumFrontiers
QUEST Leibniz Forschungsschule
Typ: Dissertation
Anzahl der Seiten: 131
Publikationsdatum: 20.02.2025
Publikationsstatus: Veröffentlicht
Elektronische Version(en): https://doi.org/10.15488/18568 (Zugang: Offen)
: Details im Forschungsportal „Research@Leibniz University“

BibTeX

@phdthesis{97f7f72b61a2480d8c072395523973f4,
title = "Metamaterials with resonant silicon nanoparticles for perfect mirrors: Investigation, design, and realisation",
abstract = "A metasurface is a single-layer artificial structure composed of specially arranged particles, which can be configured in size and shape to alter the metasurface{\textquoteright}s interaction with the incident electromagnetic field. The application potential of metasurfaces is vast, as they offer flexibility in tuning their properties while maintaining an ultra-thin, lightweight coating structure optimised for specific functionalities. Among the diverse potential applications, special attention is directed towards the field of gravitational wave physics. Gravitational wave detectors, which function as advanced Michelson interferometers, consist of highly sensitive test masses covered with reflective coatings. The next generation of detectors demands novel coating designs capable of operating at cryogenic temperatures and exhibiting minimal thermal noise. One potential alternative is a metasurface coating design that can be tailored to satisfy essential requirements. This thesis focuses on the development of highly reflective metasurfaces and their experimental realisation. In the framework of the investigation, the target wavelengths for the high-reflectivity effect are selected to be 1064nm and 1550 nm, as these are relevant to nextgeneration gravitational wave observatories. The thesis presents an analysis and description of the phenomenon of light reflection from a metasurface, originating from the resonant response of its constituent nanoparticles. Possible designs incorporating spherical and cylindrical shapes of nanoparticles are modelled and characterised through numerical simulations (Comsol Multiphysics) and a semi-analytical multipole approach. Structural optimisation, the integration of protective and supporting mediums, and their influence on performance and fabrication imperfections are considered, simulated and discussed throughout the research. On the practical side, the prototypes of the metasurface structures, composed of polycrystalline silicon cylinders on a sapphire substrate, have been realised at the selected wavelengths. The realisation process entails evaluating dimensional parameters based on the measured material properties and using a fabrication process with electron beam lithography. The characterisation of the fabricated metasurfaces demonstrates good agreement with the numerically predicted behaviour. While the primary objective is to achieve near-perfect reflectivity across all configurations, the developed analytical and numerical methods, along with the fabrication procedure, are also applicable to the development of metasurfaces with partial reflectivity or full transmissivity. These theoretical and experimental achievements in metasurface realisation have the prospect of further development and implementation in the field of gravitational wave physics and other optical experiments.",
author = "Mariia Matiushechkina",
year = "2025",
month = feb,
day = "20",
doi = "10.15488/18568",
language = "English",
publisher = "Leibniz Universit{\"a}t Hannover",
school = "Leibniz University Hannover",
}