Volume 6 Issue 2, February 2012

Researchers have shown that organic light-emitting diodes with transparent graphene electrodes are more flexible and exhibit higher efficiencies than those whose electrodes are made from rigid indium tin oxide.

By using a one-dimensional optical lattice to control and confine the location of cold ⁸⁷Rb atoms, researchers have created a distributed Bragg reflector that enables optical parametric oscillation solely from atoms.

Researchers have developed a semiconductor structure capable of supporting quantum correlations between photons and strong single-photon nonlinearities, thus paving the way for the development of chip-based devices for quantum secure communications and quantum information processing.

Photonic manipulation of the spatial distribution of charge in relativistic electron bunches provides a promising way to generate intense coherent terahertz radiation.

Using extremely broadband ultrafast near-infrared pulses, scientists have demonstrated simultaneous second-harmonic-generation, third-harmonic-generation and four-wave-mixing microscopy, enabling a range of different structures and functional groups in a biological sample to be imaged at once.

An efficient continuous-wave source of terahertz radiation that combines the outputs from two near-infrared semiconductor lasers in a novel photomixer looks set to benefit applications in spectroscopy and imaging.

Amalgamating the interdisciplinary domains of nanotechnology and terahertz technology, particularly the field of terahertz science in nanomaterials and nanodevices, seems to be where the terahertz research community is now heading.

This Review explains the concept of dissipative solitons and their application to high-energy mode-locked fibre laser cavities. Dynamics and effects such as dissipative soliton ‘explosions’ and ‘rain’ are summarized, and an outlook of the field is also provided.

Researchers observe a continuous change in photon correlations from strong antibunching to bunching by tuning either the probe laser or the cavity mode frequency. These results, which demonstrate unprecedented strong single-photon nonlinearities in quantum dot cavity system, are explained by the photon blockade and tunnelling in the anharmonic Jaynes–Cummings model.

Scientists report a record-low integrated timing error of less than 13 as between phase-locked optical pulse trains emitted from two, nearly identical 10 fs Ti:sapphire lasers. The uniform pulse trains will enable many measurements based on the synchronization of pump–probe experiments.

Researchers demonstrate one-dimensional photonic crystal lasing with the aid of a cold atom cloud that provides both gain and distributed feedback. Distributed feedback is due to the periodic distribution of the atoms trapped in a one-dimensional lattice enabling Bragg reflection, and parametric gain is provided by four-wave mixing.

By replacing conventional indium tin oxide (ITO) anodes with high-work-function, low-sheet-resistance graphene anodes, researchers demonstrate flexible fluorescent organic LEDs with extremely high luminous efficiencies of 37.2 lm W^–1 for fluorescent devices and 102.7 lm W^–1 for phosphorescent devices. These values are significantly higher than those of optimized organic LEDs based on ITO anodes.

Researchers use an X-ray pump beam to change GaAs from absorbing to nearly transparent in less than 100 ps for laser photon energies just above the bandgap. They also demonstrate the opposite effect — X-ray-induced optical opacity — for photon energies just below the bandgap.

Researchers demonstrate a high-efficiency polymer solar cell whose device architecture is compatible with a large-scale roll-to-roll process. Enhanced charge collection in the inverted polymer solar cell design and certified power conversion efficiencies of around 7.4% are reported.

Researchers report a room-temperature continuous-wave terahertz source based on a nanogap electrode structure in the active region of a photoconductive photomixer. The device has an emission linewidth of less than 10 MHz, an emission frequency of 0.3–1.6 THz and a maximum output power of 100 mW at 0.4 THz.

A semiconductor is usually opaque to any light whose photon energy is larger than the semiconductor bandgap. Nature Photonics spoke to Stephen Durbin about how to render GaAs semiconductor crystals transparent using intense X-ray pulses.