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The spin Hall effect, an interaction between particles because of their intrinsic spin, is a central tenet in the field of spintronics. The direct observation of an optical equivalent of the spin Hall effect is now reported.
Coupled optical resonators are one approach to slowing the propagation of light. An array of more than 100 such resonators has now been demonstrated using a photonic crystal. Such a structure can slow light down to below 1% of its speed in a vacuum.
Low-cost, efficient solar cells are sought as an alternative to silicon photovoltaics. Here a dye-based bifacial solar cell that is capable of efficient generation of electricity for light incident on either its front or rear face is demonstrated.
Tiny optical cavities can influence spontaneous emission of light from atoms and their artificial equivalent, quantum dots. In the past, two–dimensional photonic crystals have been used to create such cavities for quantum dots, now a three–dimensional structure enables full confinement of light in all directions.
A design of on-chip optomechanical resonator that simultaneously maximizes a high mechanical Q-factor in the megahertz range and an ultrahigh optical finesse is reported. Studies of the mechanical properties of the cavity achieve the first direct observation of mechanical normal-mode coupling in a micromechanical system.
The ability to efficiently transfer photons from a light source to an optical circuit is crucial, and requires efficient coupling of light to optical fibres and waveguides. Using state-of-the-art fabrication techniques, Hong-Gyu Park and colleagues create a device that uses nanowires to inject light into photonic-crystal waveguides in an efficient way. The structure could become an important part of the nanophotonics toolbox.
Table-top laser-driven plasma accelerators have the potential advantages of being ultracompact and powerful. Electron beams can be created by irradiating gas jets with intense laser light, however, until now it has proved difficult to achieve stable, high-energy beams. Jongmin Lee and colleagues report the first generation of stable gigaelectronvolt-class electron beams using a laser-based accelerator, and make an important step along the road to future particle accelerators.
Nanfang Yu and colleagues show that plasmonics can be used to reduce the spread of laser beams. They demonstrate their technique using a quantum cascade laser, and show that by defining a metallic subwavelength slit and grating onto the facet of the laser, a beam divergence of 2.4 degrees can be achieved. The technique can potentially be used to collimate the beams from a variety of different lasers.
Light is often thought of in terms of radial polarization, but longitudinal polarization is also possible, and it has some intriguing possibilities for particle acceleration. Binary optics, combined with a high-numerical-aperture lens, is a potential route to achieving light with this unusual property.
A stack of silver nanorods could, according to calculations, be the answer to performing subwavelength colour imaging over far-field distances. The metallic nanolens is designed to operate in the visible wavelength range and by tapering the nanorods, image magnification is also shown to be feasible. If realized such a lens could be useful for imaging applications in the biomedical sciences and other fields.
Incoherent optical spatial solitons are self-trapped beams with a multimodal structure that varies randomly in time. All incoherent solitons observed so far have been supported by nonlinearities with slow response times. Here, Segev and colleagues demonstrate such solitons in nonlinear media with fast (essentially instantaneous) response times and show that new physical features appear.
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.
Demonstration of an imaging system that can capture high-resolution 3D fluorescent images of biological speciments without the need for any moving parts.
