Articles

Precise spatial characterization of the origin of light emission from organic light-emitting diodes is important for improving the design of future devices and gaining valuable insight into their operation. Here, a characterization scheme that achieves this task with a spatial resolution better than 5 nm is reported.

A measurement scheme that is capable of recording the amplitude and phase of arbitrary shaped optical waveforms with a bandwidth of up to 160 GHz is presented. The approach is compatible with integration on a silicon photonic chip and could aid the study of transient ultrafast phenomena.

Tailoring of arbitrary single-mode states of travelling light up to the two-photon level is proposed and demonstrated. The desired state is remotely prepared in the signal channel of spontaneous parametric down-conversion by means of conditional measurements on the idler channel.

Nanocavity optomechanical systems can exhibit strong dynamical back-action between mechanical motion and the cavity light field. Here, optical control of mechanical motion within two different nanocavity structures is demonstrated. A form of optically controlled mechanical transparency is also demonstrated, which is analogous to electromagnetically induced transparency.

Fine control over the material structure within a volume gives rise to new physical phenomena and more freedom for designing spatial, spectral and temporal functions. A three-dimensional scattering approach to the design of aperiodic volume optical elements is presented, expanding the traditional capabilities of volume holography, photonic crystals and diffractive optics.

The combination of distributed Rayleigh back-scatter and Raman gain in an optical fibre yields an open cavity, mirror-less fibre laser that offers stable operation at the telecommunications wavelength of 1.5 µm.

Scientists demonstrate that a single 7.5-μm-diameter microdisk laser coupled to a silicon-on-insulator wire waveguide can work as an all-optical flip-flop memory. Under a continuous bias of 3.5 mA, flip-flop operation is demonstrated using optical triggering pulses of 1.8 fJ and with a switching time of 60 ps. This device is attractive for on-chip all-optical signal buffering, switching, and processing.

Ultrabroad-bandwidth radiofrequency pulses that increase data transmission rate and allow multipath tolerance in wireless communications are difficult to generate using chip-based electronics. Now, a chip-scale fully programmable spectral shaper consisting of cascaded multichannel micro-ring resonators is demonstrated as a solution.

Rydberg blockade — the suppression of excitation of more than one Rydberg atom within a blockade volume — has so far been realized using ultracold atoms. Now, scientists show that coherence times of >100 ns are achievable with coherent Rydberg atomic spectroscopy in micrometre-sized thermal vapour cells, making them good candidates for investigating low-dimensional strongly interacting Rydberg gases, constructing quantum gates and building single-photon sources.

The generation of random bit sequences at a data rate of up to 300 Gbit s⁻¹ — a rate many orders of magnitude faster than previously achieved — is realized by exploiting the output of a chaotic semiconductor laser. The randomness of the generated bits is verified by standard statistical tests.

A terahertz wire laser with an unprecedented tuning range of ∼137 GHz has been demonstrated. This scheme relies on bringing dielectric or metallic structures into close proximity with the wire, thus modifying the properties of its guided mode.

Whispering-gallery-mode resonators made of nematic liquid-crystal droplets offer a wavelength tunability approximately two orders of magnitude larger than that of conventional solid-state microresonators.

A streak camera for characterizing the ultrashort X-ray pulses produced by a free-electron laser is reported. The scheme has a single-shot capability, a resolution of a few femtoseconds and is expected to become a useful tool for X-ray metrology, including experiments involving time-resolved spectroscopy and imaging.

Maskless high-resolution patterning of structural colours is demonstrated using a new material called ‘M-Ink’. The period of the material is patterned magnetically and a photochemical process immobilizes the structure in a polymer network.

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.