Dynamical metasurfaces: electromagnetic properties and instabilities

• Main Author: Oue, Daigo
• Format: Journal Article
• Language: English
• Published: 16-02-2022
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Optics; Physics - Quantum Physics
• DOI: 10.48550/arxiv.2112.10378

In this thesis, I analyse the electromagnetic properties of dynamical
metasurfaces and find two critical phenomena. The first is the Casimir-induced
instability of a deformable metallic film. In general, two charge-neutral
interfaces attract with or repel each other due to the contribution from the
zero-point fluctuation of the electromagnetic field between them, namely, the
Casimir effect. The effects of perturbative interface corrugation on the
Casimir energy in the film system is studied by the proximity force
approximation with dispersion correction. If the corrugation period exceeds a
critical value, the Casimir effect dominates the surface tension and brings
about structural instability. The second is \v{C}erenkov radiation in the
vacuum from a time-varying, corrugated surface. Travelling faster than light
brings about electromagnetic shock waves, \v{C}erenkov radiation. Since light
is the fastest object in a vacuum, it has been considered that \v{C}erenkov
radiation is emitted only in the presence of some refractive index. Here, I
propose mimicking a series of particles travelling faster than light in a
vacuum by dynamical surface corrugation to find \v{C}erenkov radiation in a
vacuum from the surface. The dynamical corrugation induces an effective current
source on the surface with an external electrostatic field applied. When the
corrugation profile is of travelling wave type, the source can be regarded as a
series of dipoles virtually travelling along the surface. If the phase velocity
of the travelling wave profile exceeds the speed of light, and so do the
dipoles, they emit \v{C}erenkov radiation in a vacuum.