THESIS
2019
xx, 93 pages : illustrations (some color) ; 30 cm
Abstract
After two decades of rapid development, metasurfaces play an irreplaceable role in the
manipulation of surface electromagnetic waves. In this thesis, we will demonstrate two projects
in the designing of multifunctional metasurfaces. The first project involves a metasurface for
position sensor applications. We experimentally demonstrate that a metasurface with two
independent collimation frequencies in orthogonal directions can function as a position sensor.
The brand new sensing mechanism leads to important advantages in contrast to the traditional
working principles, thus providing a novel avenue for coordinate sensing. The second project
is the probing of the topological physics of the metasurface. The topological characteristics of
energy bands have attracted substantial inte...[
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After two decades of rapid development, metasurfaces play an irreplaceable role in the
manipulation of surface electromagnetic waves. In this thesis, we will demonstrate two projects
in the designing of multifunctional metasurfaces. The first project involves a metasurface for
position sensor applications. We experimentally demonstrate that a metasurface with two
independent collimation frequencies in orthogonal directions can function as a position sensor.
The brand new sensing mechanism leads to important advantages in contrast to the traditional
working principles, thus providing a novel avenue for coordinate sensing. The second project
is the probing of the topological physics of the metasurface. The topological characteristics of
energy bands have attracted substantial interest in condensed matter systems as well as in classic
wave systems. Among these energy bands, the type-II Dirac point is a nodal degeneracy with
tilted conical dispersion, leading to a peculiar crossing in the constant energy plane. Such nodal
points have recently been found in electronic materials. The analogous topological feature in
photonic systems remains a theoretical curiosity, with experimental realization expected to be
challenging. We experimentally realize the type-II Dirac point by employing a metasurface
architecture, where the band degeneracy point is protected by the underlying mirr or symmetry
of the metasurface. Gapless edge modes are found and measured at the boundary between the
different domains of the symmetry-broken metasurface. The designed metasurfaces are simple
and practical platforms for realizing electromagnetic type-II Dirac points. Furthermore, their
planar structure is a distinct advantage that facilitates applications in two-dimensional
topological photonics.
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