Articles tagged with "nanostructures"
Tuning the untunable: Dirac waves gain new control in terahertz devices
The article discusses a breakthrough in controlling Dirac plasmon polaritons (DPPs), exotic waves that combine light with electron motion in ultra-thin materials, specifically in the terahertz (THz) frequency range. THz waves, which lie between microwaves and infrared light, have long been difficult to harness due to rapid energy loss and poor controllability. The researchers addressed this by using topological insulator metamaterials made from epitaxial Bi2Se3, which conduct electricity only on their surfaces, allowing electrons to behave as massless particles. By designing laterally coupled nanostructures ("metaelements") and precisely adjusting their spacing, they successfully tuned the DPPs’ behavior, increasing the polariton wavevector by up to 20% and extending the attenuation length by over 50%, enabling tighter light confinement and longer propagation with less energy loss. This advancement paves the way for more efficient, tunable THz photonic devices with broad applications, including
materialsterahertz-devicesnanostructurestopological-insulatorsplasmon-polaritonsphotonicsquantum-devicesHot-cold design supercharges solar thermoelectric efficiency by 15x
Researchers at the University of Rochester have developed a novel "hot-cold" design that increases the efficiency of solar thermoelectric generators (STEGs) by 15 times, potentially bridging the gap between STEGs and conventional photovoltaic solar panels. Unlike traditional solar panels that rely on photovoltaic cells, STEGs generate electricity by exploiting the temperature difference between a hot side and a cold side through the Seebeck effect. Historically, STEGs have been limited by low efficiency, converting less than 1% of sunlight into electricity compared to about 20% for residential solar panels. The new approach improves efficiency not by altering semiconductor materials but by enhancing thermal management on both the hot and cold sides of the device. The innovations include using femtosecond laser pulses to etch nanoscale structures into tungsten on the hot side, creating a "black metal" surface that selectively absorbs solar wavelengths while minimizing heat loss. This surface is covered with a plastic layer that traps heat by limiting convection and conduction, effectively raising
energysolar-energythermoelectric-generatorsrenewable-energythermal-managementsemiconductor-materialsnanostructuresPeacock Feathers Are Stunning. They Can Also Emit Laser Beams
A recent study published in Scientific Reports reveals that peacock feathers, known for their vivid iridescent colors produced by nanostructured photonic crystals, can also emit laser light when repeatedly dyed. Unlike pigments, the feathers’ colors arise from the precise periodic arrangement of melanin rods coated in keratin within the barbules, which act as tunable photonic crystals that selectively reflect certain wavelengths. By staining the feathers multiple times with dye and then exciting them with light pulses, researchers observed laser emissions at two distinct wavelengths across the feathers’ eyespot regions, with green areas producing the strongest laser light. Single staining was insufficient to induce lasing, likely due to limited dye diffusion and structural constraints. Although the exact microstructures responsible for the laser effect remain unidentified, the study suggests that protein granules or other small internal features, rather than the keratin-coated melanin rods themselves, may serve as the laser cavity. This discovery not only advances understanding of natural photonic structures but also holds promise for
materialsphotonic-crystalsbiolasernanostructuresiridescencebiomimicryoptical-materialsScientists simulate how tens of thousands of electrons move in real time
materialsenergyquantum-mechanicselectron-dynamicsphotovoltaic-cellssimulationnanostructures