Nanowerk September 22, 2022 A team of researchers in the US (University of Michigan, University of Virginia) has developed materials using destructive interference phenomenon to reflect infrared energy while letting shorter wavelengths pass through. Using pulsed laser, they deposited oxides of calcium and titanium oxides. Oxides made the material more durable, less likely to degrade at high temperature, and they could be more precisely layered. The material controlled the flow of infrared radiation and was stable at temperatures of 2,000 degrees Fahrenheit in air, a nearly twofold improvement over existing approaches. After testing they confirmed that the material worked as […]
Tag Archives: Nanophotonics
Breaking an optical rule: Engineers find a way to manipulate light at the nanoscale
Phys.org September 12, 2022 According to Moss rule the absorption edge and the sub-bandgap refractive index of a semiconductor exhibit a rigid trade-off setting an upper limit on the refractive index of a dielectric for a given operating wavelength. According to a team of researchers in the US (Rice University, Johns Hopkins University) there are many dielectric materials that surpass the Moss rule, referred to as super-Mossian dielectrics. They discussed the general features of super-Mossian dielectrics and their physical origin to facilitate the search for high index dielectrics. They developed iron pyrite with index nearly 40% higher than the Moss […]
Nano-architected material refracts light backward – an important step toward one day creating photonic circuits
Nanowerk January 28, 2022 Negative refraction has not been observed in nature but was theorized to occur in artificially periodic materials. Researchers at Caltech designed, fabricated 3D photonic crystals (PhCs) capable of negative refraction in the mid-infrared. Band structure and equifrequency contours were calculated to inform the design of 3D polymer–germanium core–shell PhCs. They successfully characterized a polymer–Ge core–shell lattice and mapped its band structure, which were used to calculate the PhC refraction behavior. An analysis of wave propagation revealed that this 3D core–shell PhC refracts light negatively and possesses an effective negative index of refraction in the experimentally observed […]
A nanoantenna for long-distance, ultra-secure communication
Phys.org November 16, 2021 Converting photon-based information to electron-based information are highly inefficient. To increase the efficiency of converting single photons into single electrons in gallium arsenide quantum dots an international team of researchers (Japan, Germany) designed a nanoantenna, consisting of ultra-small concentric rings of gold, to focus light onto a single quantum dot. It resulted in a voltage readout from their device enhancing photon absorption by a factor of up to 9. After illuminating a single quantum dot, most of the photogenerated electrons weren’t trapped there, instead accumulated in impurities or other locations in the device. Nevertheless, these excess […]
The nanophotonics orchestra presents: Twisting to the light of nanoparticles
Science Daily September 20, 2021 In 3D isotropic liquids, optical third-harmonic generation is forbidden, with circularly polarized light (CPL). Yet the associated nonlinear susceptibility directly influences the optical properties at the fundamental frequency by intensity dependence. An international team of researchers (UK, Germany) has revealed the hidden third-harmonic optical properties upon circularly polarized light (CPL) by demonstrating a new effect, in hyper-Rayleigh scattering. The intensity of light scattered at the third-harmonic frequency of the CPL incident light depends on the chirality of the scatterers. It is referred to as third harmonic (hyper) Rayleigh scattering optical activity (THRS OA) and was […]
Light-controlled nanoparticles will play key role in biosensor development
Phys.org May 11. 2021 An international team of researchers (Russia, Singapore) made nanoparticles composed of silicon cores and biopolymer shells. The substances that make up the shells have different hydrophobic/hydrophilic qualities using which they could make the particles contract or expand depending on external factors. The nanoparticles change both shape and color under thermal influence. The new controllable systems can also be used to create thermo- and light-controlled dyes akin to liquid-crystal modulators used in holography and lithography. Changes in the color of the particles occur solely due to structural transformations. Change in color allows monitoring the particle in real […]
Physicists fight laser chaos with quantum chaos to improve laser performance
Phys.org August 18, 2018 The instabilities in the laser are caused by optical filaments, light structures that move randomly and change with time, causing chaos. An international team of researchers (USA – Yale University, UK, Singapore) designed a D-shaped cavity for the laser to induce quantum chaos in the light bouncing around. By creating quantum (wave) chaos in the cavity the laser itself remained steady. The quantum chaos acts on a smaller scale than the wavelength of the light, creating the optical ‘hills’ that help to dispel the optical ‘tornadoes’. They gained insight into the processes and cavity shapes likely […]