Researchers have demonstrated the experimental realization of the first all-carbon optical diode that is ready for scalable integration along with being inherently broadband in operation with no restrictions on polarization or phase-matching criteria. As they show, harnessing the optical properties of graphene-based materials offers an opportunity to create the all-photonic analogs of diodes, transistors, and photonic logic gates that will one day enable construction of the first all-photonic computer.
Aluminum has gained interest in the field of nanoplasmonics not only because it is abundant and costs a fraction of gold or silver, but also because it allows field-enhancement effects into the ultraviolet. However, it has broader resonances than silver and gold, and forms an oxide layer. Both these effects are undesirable in applications such as biosensing, in which signal strengths are reduced in the presence of resistive losses and oxide barriers. However, color printing based on the plasmon resonances of aluminum nanostructures could benefit from these properties. Researchers have now demonstrated, for the first time, the utility of aluminum nanostructures for ultrahigh definition plasmonic color printing.
The light-emitting electrochemical cell (LEC) shares several external attributes with the OLED, notably the opportunity for soft areal emission from thin-film devices, but its unique electrochemical operation eliminates the principal requirement on inert-atmosphere/vacuum processing as it can comprise solely air-stabile materials. This important intrinsic advantage has inspired recent work on an ambient-air fabrication of LEC devices using scalable means. Introducing a new, purpose-designed spray-sintering deposition technique, researchers have now shown that it is possible to spray out liquid inks onto essentially any surface for the achievement of light emission.
Recently, a new Dirac material - a lattice system where the excitations are described by relativistic Dirac or Weyl equations - namely a topological insulator (TI), entered researchers' sight. TIs possess a small band gap in their bulk state and a gapless metallic state at their edge/surface. A research group working on two-dimensional materials photonicshas now experimentally demonstrated for the first time that TI may be a novel microwave-absorbing material.
A conventional optical microscope equipped with an oil immersion objective can resolve objects no smaller than about 200 nanometers - a restriction known as the diffraction limit. The diffraction limit, which typically is half the width of the wavelength of light being used to view the specimen, represents the fundamental limit of optical imaging resolution. Breaking this limit is possible by very sophisticated techniques and costly instrumentation. Now, though, researchers in Switzerland have found that when putting a transparent dielectric particle on top of an object with nanoscale features, details of that object with a size as small as one fourth of the diffraction limit can be resolved using a conventional microscope objective.
Following extensive research in the field of bionano-interfaces, it is now well understood that the primary interaction of biological species with nanoparticles is strongly dependent to the long-lived protein corona, i.e. a strongly adsorbed protein layer at the surface of nanoparticles. The amount, composition, and exposure site of the associated proteins in the long-lived protein corona can define the biological response to the nanoparticles and hence reveal their biological fate. Scientists have now shown that laser plasmonic heat induction leads to significant changes in the protein corona composition at the surface of gold nanorods.
Over the past decade, electromagnetic metamaterials have become an extremely active field of research in both the physics and the engineering communities. Metamaterials gain their properties from their structure rather than directly from their composition and show the peculiarity of having an index of refraction at optical frequencies from negative to very high positive values. Researchers have now suggested a new type of optical sensing device based on artificial metamaterials with topological darkness.
Technology in our lives is ever more based on miniaturized structures that deliver higher performance devices taking up a fraction of the space compared to several years ago. But seeing what is going on at these tiny length scales comparable to molecules is very hard. Normally light cannot be used since it is not focused tightly enough, limited by the optical wavelength which is much larger than the structures we want to observe. New research suggests that tightly squeezing light into small gaps in metallic nanostructures now provides a way to circumvent this problem.