Articles

Spectroscopy that combines the accuracy of a frequency comb with the ease of use of a tunable, external cavity diode laser is demonstrated, enabling precise dispersion measurements of microresonator modes.

All-optical wavelength routing based on optical gradient force in mechanically compliant spoked resonators is demonstrated over a wavelength range that is 3,000 times greater than the resonator linewidth. A switching time of less than 200 ns, a tuning efficiency of 309 GHz mW⁻¹ and 100% channel-quality preservation over the entire tuning range is achieved.

The power-conversion efficiency of dye-sensitized solar cells is increased by 26% by using energy relay dyes. The scheme aids the absorption of high-energy photons that undergo Förster resonant energy transfer to a sensitizing dye, and may offer a viable pathway for developing more efficient dye-sensitized solar cells.

Opto-acoustic imaging of fluorescent proteins deep within living organisms (Drosophila melanogaster and zebrafish) is reported. The approach uses multiple wavelength illumination of the sample to generate ultrasound waves which are then detected and converted into images.

Precise control of single-photon states and multiphoton entanglement is demonstrated on-chip. Two- and four-photon entangled states have now been generated in a waveguide circuit and their interference tuned. These results open up adaptive and reconfigurable photonic quantum circuits not just for single photons, but for all quantum states of light.

Bright, efficient and low-drive-voltage colloidal quantum-dot LEDs that have a crosslinked-polymer quantum-dot layer, and use a sol–gel titanium oxide layer for electron transport, are reported. Integrating the QD-LEDs with a silicon thin-film transistor backplane results in a QD-LED display.

Using two coherent broadband fibre-laser frequency comb sources, a coherent laser ranging system for absolute distance measurements is demonstrated. Its combination of precision, speed and long range may prove particularly useful for space-based sciences.

A polymer solar-cell based on a bulk hetereojunction design with an internal quantum efficiency of over 90% across the visible spectrum (425 nm to 575 nm) is reported. The device exhibits a power-conversion efficiency of 6% under standard air-mass 1.5 global illumination tests.

An ambient light display based on electrofluidic control of coloured pigment fluids is reported. Electromechanical pressure is used to move the pigment from a reservoir to the entire surface of a pixel on a timescale of tens of milliseconds. The display has a white light reflectivity of 55%.

By applying a magnetic field to an atomic vapour, it is shown that the large bandwidth of off-resonance slow-light media can be combined with the Faraday effect to realize a high-bandwidth dispersive probe for atomic systems. This will open up the possibility of probing atomic dynamics on a nanosecond timescale.

Using a near-field transducer with efficient optical energy transfer, researchers demonstrate proof-of-principle heat-assisted magnetic recording with multi-track data density of ∼375 Tb m⁻².

Blue light-emitting diodes with a light extraction efficiency of 73% are reported. The InGaN–GaN devices use a photonic-crystal structure for superior optical mode control; their performance has been characterized experimentally and modelled theoretically.

Controlling the orientation of the constituent parts of a metamaterial enables the creation of a new family of optical stereoisomer materials that have an electromagnetic response that can be carefully tailored.

The coherent storage and retrieval of a four-wave-mixing normal mode in a hot atomic rubidium vapour may prove to be useful for future information processing schemes.

The combination of spectrally resolved two-photon microscopy, fluorescent tags and appropriate theory makes it possible to determine the complex size, configuration and spatial distribution of proteins in single living cells. The findings made could lead to ways of tracking the cellular dynamics of individual molecular complexes.

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.