In this paper, the Comsol Multiphysics version 5.0 is used to study the effect of geometric parameters on transmission of chiral met-amaterial nanostructures. The angle of the chiral metamaterial element was varied to see his effect. Transmission coefficient (S21) and reflection coefficient (S11) are computed. In the case of nano chiral metamaterial structure, and depending on the application, the electromagnetic behavior can be adjusted by changing the angle of the chiral element.
Three-dimensional
chiral plasmonic metasurfaces were demonstrated
to offer enormous potential for ultrathin circular polarizers and
applications in chiral sensing. However, the large absorption losses
in the metallic systems generally limit their applicability for high-efficiency
devices. In this work, we experimentally and numerically demonstrate
three-dimensional chiral dielectric metasurfaces exhibiting multipolar
resonances and examine their chiro-optical properties. In particular,
we demonstrate that record high circular dichroism of 0.7 and optical
activity of 2.67 × 105 degree/mm can be achieved based
on the excitation of electric and magnetic dipolar resonances inside
the chiral structures. These large values are facilitated by a small
amount of dissipative loss present in the dielectric nanoresonator
material and the formation of a chiral supermode in a 4-fold symmetric
metasurface unit cell. Our results highlight the mechanisms for maximizing
the chiral response of photonic nanostructures and offer important
opportunities for high-efficiency, ultrathin polarizing elements,
which can be used in miniaturized devices, for example, integrated
circuits.
We experimentally study the effect of rotational disorder at the unit-cell level on the optical response of chiral bilayer plasmonic metasurfaces consisting of asymmetric dimers of gold nanoantennas. The structures are fabricated based on a two-step electron-beam lithography process in combination with a precision alignment procedure. For a comprehensive characterization of the chiral optical response of the fabricated bilayer metasurfaces, we combine two different measurement strategies, namely, direct measurement of the circular transmission using circularly polarized incident light and measurement of the Jones matrix using interferometric spectroscopy with linearly polarized incident light. This allows us both to do a comprehensive analysis of the polarization dependent properties and to retrieve the effective polarization eigenstates of the metasurface in the ordered and disordered regime directly from experimental data. Our results demonstrate that rotational disorder provides a route toward chiral plasmonic metasurfaces with orthogonal, purely circular eigenstates, leading to circular dichroism and optical activity without linear birefringence. Our experimental findings are additionally complemented and verified by numerical simulations for the ordered case.
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