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Optical antennas are able to concentrate light on a scale much smaller then the wavelength. By using the probe of an atomic force microscope, it is possible to manipulate a so-called bow-tie antenna, thereby tuning its optical response.
Two-photon emission has now been observed from an electrically pumped semiconductor. The process, which involves the simultaneous generation of correlated photons, could have important implications for quantum information technology.
How black is black? An ideally black material would absorb light perfectly at all angles for all wavelengths. Using arrays of carbon nanotubes, researchers based in New York have now engineered a metamaterial that constitutes the darkest material ever made.
The increase in laser-diode sales has had a knock-on effect on activity in the diode-driver market. Neil Savage gives an update of the latest products on offer.
The burgeoning field of nanophotonics is taking light into places that did not seem possible. Optical antennas could, in the not-so-distant future, provide a new way of observing the different components of a cell and studying their interaction.
The use of inorganic charge transport layers has enabled the fabrication of bright, environmentally stable LEDs that are based on electrically pumped colloidal solutions of quantum dots.
Although electronic paper that can display monochrome static images has been growing in popularity, the next generation of products will soon be capable of displaying video in full colour. Duncan Graham-Rowe reports.
Optical antennas have already been shown to dramatically enhance molecular excitation and emission processes. Now, a compelling new study illustrates how they can redirect the emission of single molecules.
Interactions between laser and matter are fascinating and have found a wide range of applications. This article gives an overview of the fundamental physical mechanisms in the processing of transparent materials using ultrafast lasers, as well as important emerging applications of the technology.
Silicon photonics is deemed to be the solution for dense on-chip optical networks. Now, by using cascaded silicon microring resonators, scientists demonstrate an ultracompact switch that is insensitive to wavelength and temperature. The switch also has fast error-free operation in multiple 40-Gbit s−1 optical channels and is suitable for scalable networks.
By scaling down device size, the principles of radio antennas can be used in the optical regime. These optical antennas act as a bridge between optics and electronics, collecting and enhancing light to enable the creation of tiny semiconductor photodetectors.
Antennas are used to direct the propagation of radio waves. However, this directionality is not so easy to achieve at optical frequencies. Optical antennas that can direct the emission from single fluorescent molecules represent an intriguing route to single-photon sources.
The authors show that metal oxide and colloidal quantum dots can be combined to fabricate monochrome LEDs with a brightness that matches that of the best organic-based quantum-dot LEDs, but with the advantage of improved shelf-life robustness. The reported maximum external electroluminescence efficiency is nearly 0.1%, which represents a 100-fold improvement over previously reported structures
It has been known for many decades that tightly focusing light introduces asymmetry. The impact of this on imaging, as is now demonstrated using solid immersion lenses, is that resolution becomes dependent on the polarization of the light.
Optical antennas are able to concentrate light on a scale much smaller then the wavelength. Bow–tie–shape nanostructures are one example. It is now possible to tune the response of such an antenna by precisely moving one half of the bow tie.
It is possible that when an electron relaxes from an excited state, it generates not one but two photons. Such two–photon emission has been seen in atomic systems, but never in semiconductors, until now. The experimental observation could have intriguing implications for quantum optics.
Research in photonics often yields considerable commercial opportunities. However, basic research that has no obvious near-term applications is also vital for the field's evolution.
