Abstract
A switchable chiral metasurface based on a phase change material Ge2Sb2Te5, which can switch between a right-handed circularly polarized mirror and a left-handed circularly polarized mirror, is theoretically discussed. When the conductivity of Ge2Sb2Te5 σ is 0 S/m, the metasurface will reflect incident right-handed circularly polarized light and absorb incident left-handed circularly polarized light at 0.76 THz. As σ is set to 3 × 105 S/m, the response of the metasurface to circularly polarized light will be reversed. That is, it reflects the incident left-handed circularly polarized light and absorbs the incident right-handed circularly polarized light at 0.66 THz. The circular dichroism is from 76% to −64%. Then, we also study the performance of the mirror structure of the initial metasurface. By simulating the reflected spectra with different conductivities and the surface current distribution, the reason for the switchable function is clear. Moreover, the switchable chiral metasurface can be applied in spin-selective beam deflectors, which is proven by simulation. This work provides a new strategy for the development of tunable chiral devices.
Highlights
Chirality is an inherent feature of chiral molecules
The study of the interaction between circularly polarized light (CPL) and matter has been involved in many wavebands, such as microwave [11], terahertz [12], infrared [13] and visible [14]
It is well known that chiral metamaterials show different electromagnetic responses such as asymmetric transmission (AT) and circular dichroism (CD) when they interact with CPL with different spins
Summary
Chirality is an inherent feature of chiral molecules. Similar to our left and right hands, they mirror each other and cannot overlap. Chiral objects and their mirror images are called enantiomers. There are many chiral molecules, such as protein, DNA, sugar molecules, viruses, amino acids and liquid crystals, but there are few chiral structures in nature. It is well known that chiral metamaterials show different electromagnetic responses such as asymmetric transmission (AT) and circular dichroism (CD) when they interact with CPL with different spins. Chiral metamaterials have selective transmission, reflection and absorption of incident CPL with different spins
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