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Temperature‐Controlled Optical Activity and Negative Refractive Index
- Source :
- Advanced Functional Materials. 31:2010249
- Publication Year :
- 2021
- Publisher :
- Wiley, 2021.
-
Abstract
- Chiral media exhibit optical activity, which manifests itself as differential retardation and attenuation of circularly polarized electromagnetic waves of opposite handedness. This effect can be described by different refractive indices for left- and right-handed waves and yields a negative index in extreme cases. Here we demonstrate active control of chirality, optical activity and refractive index. These phenomena are observed in a terahertz (THz) metamaterial based on three-dimensionally (3D) chiral metallic resonators and achiral vanadium dioxide inclusions. The chiral structure exhibits pronounced optical activity and a negative refractive index at room temperature when vanadium dioxide is in its insulating phase. Upon heating, the insulator-to-metal phase transition of vanadium dioxide effectively renders the structure achiral, resulting in absence of optical activity and a positive refractive index. The origin of the structure’s chiral response is traced to magnetic coupling between front and back of the structure, while the temperature-controlled chiral-to-achiral transition is found to correspond to a transition from magnetic to electric dipole excitations. The use of a fourfold rotationally symmetric design avoids linear birefringence and dichroism, allowing such a structure to operate as tunable polarization rotator, adjustable linear polarization converter and switchable circular polarizer.
- Subjects :
- Phase transition
Materials science
Polarization rotator
Linear polarization
Physics::Optics
Metamaterial
02 engineering and technology
Dichroism
Polarizer
010402 general chemistry
021001 nanoscience & nanotechnology
Condensed Matter Physics
01 natural sciences
Electromagnetic radiation
Molecular physics
0104 chemical sciences
Electronic, Optical and Magnetic Materials
law.invention
Biomaterials
law
Electrochemistry
0210 nano-technology
Refractive index
Subjects
Details
- ISSN :
- 16163028 and 1616301X
- Volume :
- 31
- Database :
- OpenAIRE
- Journal :
- Advanced Functional Materials
- Accession number :
- edsair.doi.dedup.....83f5ef66d889ab1a61545f1f3e5da9f6
- Full Text :
- https://doi.org/10.1002/adfm.202010249