posted on 2023-02-02, 20:05authored byYuanhai Lin, Heng Guo, Deqing Che, Junsheng Wang
This paper describes a quasi-planar chiral metamaterial
of metal–insulator–metal
(MIM) tetramer arrays that support multiplasmon modes from a hybridization
scheme to achieve significant chiroptical responses with the largest
circular dichroism (CD) value of 42%. The chiroptical responses can
be actively switched on and off by tuning the field coupling regime
from near field to far field through the insulator (or spacer) thickness.
Numerical calculations demonstrate that near-field coupling of the
hybridized plasmons on the stacked metallic tetramers governs the
chiroptical responses at small insulator thickness (tSiO2 < 160 nm). In contrast, far-field coupling of
the plasmon radiations dominates at large spacing (tSiO2 > 160 nm) as phase retardation plays a crucial
role.
The quasi-planar chiral metamaterial with tunable plasmonic chirality
enables efficient light modulation for polarization conversion: from
circular to elliptical/linear polarization.