Research articles

Researchers realize a zero-angular-momentum radial-emission laser by filling a cylindrical photonic crystal fibre cavity with a microfluidic gain medium. Control of the electromagnetic fields is provided by electrically contacted and independently addressable liquid-crystal microchannels in the fibre.

High-efficiency fluorescent organic light-emitting diodes have been realized by employing custom-designed molecules that make it possible to convert non-radiative triplet states into radiative singlet states.

Researchers observe heralded entanglement between two neodymium ensembles doped in Nd³⁺:Y₂SiO₅ crystals separated by 1.3 cm. The high level of interference indicates that the stored entanglement does not significantly decohere over a period of 33 ns. They demonstrate that rare-earth-ion ensembles have the potential to form compact, stable and coherent quantum network nodes.

By exciting few-cycle femtosecond laser pulses at 397 nm in near-resonance with the direct bandgap of silicon, researchers experimentally demonstrate coherent phonon generation in silicon at a fundamental frequency of 15.6 THz and all-optical >100 THz frequency comb generation.

Researchers consider electromagnetic dissipation in metamaterials and plasmonic systems comprised of various materials. They predict that graphene and high-temperature superconductors may not be suitable for practical resonant metamaterial applications and are unlikely to outperform conventional metals in plasmonics. Transition metals, alkali metals and transparent conducting oxides are also discussed.

Using photonic crystal cavities with a buried heterostructure design, scientists demonstrate all-optical RAM at power levels 300 times lower than previous attempts. The 30 nW devices could enable low-power large-scale optical RAM systems for handling high-bit-rate optical signals.

Researchers demonstrate that an individual Mollow sideband channel of the resonance fluorescence from an InGaAs quantum dot can act as an efficient single-photon source. The central frequency of the bright and narrow sideband emission can be changed by laser detuning over a range spanning 15 times the emission linewidth.

By applying catastrophe theory to high-harmonic generation, researchers identify caustics relating to regions of spectral focusing and greatly enhanced field intensity.

Inspired by thermal expansion and refractive index changes in the nanostructures of iridescent Morpho butterfly scales, scientists demonstrate upconverted mid-wave infrared detection with a temperature sensitivity of 18–62 mK and a heat-sink-free response speed of 35–40 Hz.

Researchers demonstrate the creation of an eight-photon Schrödinger-cat state with genuine multipartite entanglement by developing noise-reduction multiphoton interferometer and post-selection detection. The ability to control eight individual photons will enable new multiphoton entanglement experiments in previously inaccessible parameter regimes.

Researchers demonstrate that PBDTT-DPP, a semiconducting polymer with a low bandgap of 1.44 eV, allows tandem polymer solar cells to reach power conversion efficiencies of around 8.6%.

Fabricating doped semiconductor layers and p–n junctions inside silica optical fibres allows the realization of a new breed of in-fibre optoelectronic devices, such as photodetectors with gigahertz bandwidths.

Using electro-optically generated frequency combs, scientists demonstrate radiofrequency photonic filters that can potentially provide simultaneous high stopband attenuation, fast tunability and bandwidth reconfiguration.

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.

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 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.

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.