Manipulating Electromagnetic Fields with Advanced Metamaterials

In almost any scientific experiment, we take into account some particular properties of materials, e.g. electromagnetic, mechanical, thermal, etc. These properties determine a majority of the physical phenomena that arise from the interaction with matter, and thus restrict potential applications of natural materials. The discovery and subsequent development of novel materials regularly boost the standards of living through new technological progress and cutting-edge research. One of the very recent and promising discoveries is related to the field of metamaterials - artificially structured media with subwavelength patterning. These artificial materials offer a unique platform with large flexibility and unusual properties for tailoring acoustic and electromagnetic waves, including novel ways for the manipulation of light. In this thesis, I employed the concept of metamaterials for both the study of new physical phenomena related to the emerging field of topological photonics and also develop innovative applications of specific metamaterials for the advancing the magnetic resonance imaging (MRI) machines. Chapter 1 provides an introduction to the field of metamaterials and their unusual properties, starting from the definition of meta-atoms and expanding to more complex structures, including one-dimensional meta-chains and metasurfaces. This is followed by an introduction to the fields of topological photonics and magnetic resonance imaging techniques. The experimental approaches based on a microwave platform are also described. Finally, the thesis motivation and structure are summarized. Chapter 2 presents experimental studies of topological features of zigzag arrays of dielectric particles. It includes the first experimental observation of the subwavelength photonic topological edge states, topological phase transition in the chains of dielectric particles, as well as, the study of the specific features of the photonic spin Hall effect mediated by the excitation of the subwavelength topological edge states. Chapter 3 describes the study of bianisotropic metasurfaces and metamaterials. The experimental designs of bianisotropic metallic and dielectric metasurfaces are presented, with a direct observation of topologically nontrivial edge states. Further, it is revealed how to couple topologically protected metasurfaces to form three-dimensional all-dielectric topologically nontrivial bianisotropic metamaterials and metacrystals. Chapter 4 focuses on the study metasurfaces based on resonant arrays of metallic wires used for advancing magnetic resonance imaging (MRI) characteristics. A new conceptual idea for the substantial enhancement of signal-to-noise ratio of a 1.5T MRI is presented. This approach is further developed and extended to ultra-high field MRI (7T) where a direct evaluation of the metasurface properties is examined during in-vivo human brain imaging. Chapter 5 summarizes the results and concludes the thesis