Dielectric tetrahedrons as terahertz resonators switched from perfect absorber to reflector

Abstract

Tetrahedrons are basic building blocks in natural and artificial materials, while the terahertz response of micro tetrahedrons has been little explored. Here we fabricate subwavelength ceramic tetrahedrons for use in the terahertz frequency range, and find that the three-dimensional geometry significantly affects their terahertz properties. The transmission spectra are independent of the orientation of the tetrahedrons, while the first magnetic resonance disappears in the reflection spectra when an upright tetrahedron is flipped upside down on the metallic substrate, which changes it from a perfect absorber to a perfect reflector. This is attributed to the destructive interference between two magnetic dipoles induced respectively by the incident and the reflected wave. The study brings new insights in the materials design with 3D building blocks to realize more interesting and exotic terahertz properties.

Microfluidic Assembly of Microblocks into Interlocked Structures for Enhanced Strength and Toughness

“…Such a channel was fabricated by bonding two substrates, each made by casting polydimethylsiloxane (PDMS) on a mold (Figure S1, Supporting Information). The branch of the y-shaped channel (inlet 1) was used as the fabrication channel (FC), where OMPs were fabricated from ultraviolet (UV) curable silica suspension by using the orthogonal projection method (Figure B, left). , Specifically, the octahedral profile was realized by cropping the rhombic cross section of the FC with a perpendicular beam of UV light projected through the mask with a rhombic aperture (Figure S2, Supporting Information). The UV-cured OMPs were then translated to the junction of the y-shaped channel, where they were transferred to the assembly channel (AC) and continuously flowed downstream.…”

“…The materials of the IPs are now only restricted to high-transparency materials such as hydrogel and silica. A lot of opaque materials possessing remarkable mechanical properties such as zirconia, silicon nitride, and silicon carbide are not available . An additional limitation is the discontinuous production process of our approach.…”

“…A lot of opaque materials possessing remarkable mechanical properties such as zirconia, silicon nitride, and silicon carbide are not available. 22 An additional limitation is the discontinuous production process of our approach. The frequent unloading of the chains has an influence on their monodispersity, which may reduce the assembly precision of the IPs.…”

Tailoring 3D shapes of polyhedral milliparticles by adjusting orthogonal projection in a microfluidic channel

“…When θ = 180°, the shape of the PMPs becomes regular tetrahedron, which is the simplest polyhedral geometry. Tetrahedral milliparticles have been demonstrated as the building blocks of the terahertz resonator, which can switch the resonator from the perfect absorber to reflector due to the special asymmetrical structure 39 …”

“…Tetrahedral milliparticles have been demonstrated as the building blocks of the terahertz resonator, which can switch the resonator from the perfect absorber to reflector due to the special asymmetrical structure. 39…”