Topic
Metasurfaces and metamaterials research, explained
14 open-access metasurfaces and metamaterials studies, each with a flashcard deck and a quiz.
- Can a flat lens focus all colours to the same spot?
By designing nanopillars that control both the phase and how phase changes with wavelength, the authors built flat lenses that focus a broad band of infrared light to nearly the same point.
- Can a flat optic control both brightness and phase of light?
By varying both the shape and the rotation of tiny silicon pillars, a flat metasurface can set the brightness and the phase of light independently, giving cleaner holograms than phase-only designs.
- Can one metasurface store many holograms selected by polarization?
By controlling both the shape and the rotation of tiny silicon pillars, a single flat metasurface can show different holographic images depending on which polarization of light goes in and which is let out.
- Can one flat optic control brightness and phase for two polarizations?
Pairing two kinds of rotated titanium dioxide nanopillars lets a single transparent metasurface imprint completely separate brightness and phase patterns on two opposite polarizations of light.
- Can one flat lens read both a light beam's spin and its twist?
A single patterned metasurface turns each twisted light beam into a focal spot whose angle reveals its orbital angular momentum and whose half of the screen reveals its spin.
- Can we design big, efficient metasurfaces without supercomputers?
Breaking a lens design into small straight-line sections, optimising each by computer and stitching them together gives large metasurfaces that focus light efficiently even at steep angles.
- Can stacking a colour filter on a metasurface make colour holograms?
Stacking tiny thin-film colour filters underneath a flat hologram-making nanostructure layer produced full-colour holograms with little colour mixing and no need for a particular polarisation.
- Can layered metasurfaces do logic with plain light waves?
A two-layer patterned dielectric sheet, trained like a neural network, sent microwaves to the correct 'on' or 'off' spot for NOT, OR and AND logic without precise control of the input beams.
- Can one metasurface hide both an image and a hologram?
Because several nanostructure orientations transmit the same brightness under Malus's law, the spare choice can encode a separate hologram, letting one metasurface show a picture up close and a different image far away.
- Can graphene switch mid-infrared light fast with low voltage?
Adding gate-tunable graphene to a nanoantenna metasurface lets a few volts switch mid-infrared reflection by up to 90% at gigahertz speeds, fast enough for high-frame-rate single-pixel imaging.
- Can nanostructures give switchable colors with true blacks?
Elongated silicon nanostructures reflect a bright color for one light polarization and almost nothing for the perpendicular one, so a liquid-crystal layer that rotates polarization can dial each pixel smoothly from vivid color to deep black.
- Can graphene's conductivity make infrared sensors detect tiny molecules?
Putting graphene over metal nano-antennas lets molecules that dope the graphene shift the infrared resonance strongly, detecting glucose down to picomolar levels.
- Can one flat metasurface shape both a beam's wavefront and polarization?
By giving each tiny antenna a fully tailored polarization response, a flat metasurface can produce light beams with designed wavefronts and position-dependent polarization, including on-surface plasmon vortices.
- Can one flat surface treat left and right circular waves differently?
By making two resonators in each cell interfere constructively for one circular polarization and destructively for the other, a thin metasurface reflects one spin almost perfectly while absorbing the other.