Research articles

We report the experimental observation of one- and two-dimensional grating patterns formed in a disordered metal-nanoparticle layer by a single light pulse. The phenomenon is attributed to interference effects between the incident light and waveguided modes. Such self-patterning behaviour could be useful for the fabrication of complex nanostructures and advanced photonic devices.

Optical tweezers are well known for being able to control and move microscopic objects with high precision using focused laser beams. Alexander Grigorenko and colleagues report three-dimensional tweezers based on coupled pairs of gold nanodots in standard tweezer set-ups, which offer improved trapping efficiencies and reduced trapping volumes. Their tweezers could pave the way to improved manipulation of fragile, tiny biological objects.

Light absorbers are not 100% efficient, and it is a challenge to absorb light completely for any direction of incidence. Using nanostructured metal surfaces, de Abajo and colleagues show that such omnidirectional absorption is now possible, potentially leading to more efficient solar cells.

Optical-frequency antennas efficiently couple light into very small volumes. Introducing an important concept from radiofrequency antenna design, that of loading with so-called lumped circuit elements, may provide a way of tuning the frequency response of optical nanoantennas.

Laser-generated plasmas are important for the creation of X-ray lasers and attosecond light pulses, but observing the internal dynamics of a plasma is difficult. This paper reports a method for real-time imaging of the electric-field distribution in such plasmas with ultrahigh temporal resolution, yielding a new insight into their behaviour

Metamaterials that possess frequency tunability enable new device functions. By external optical control through the incorporation of semiconductors in metallic split-ring resonators, the researchers provide an elegant solution to frequency-agile terahertz metamaterials.

The drive to develop detectors capable of counting the number of photons in a weak optical pulse is motivated by potential applications in quantum computing. Superconducting nanostructures are one exciting approach: offering high sensitivity and operate at repetition rates up to 80 MHz.

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.

Demonstration of an imaging system that can capture high-resolution 3D fluorescent images of biological speciments without the need for any moving parts.