Letters in 2019

A high-speed wireless THz communication link is seamlessly integrated into a fibre-optic network. The demonstration relies on an ultra-broadband modulator exploiting two-dimensionally localized gap plasmons for direct conversion of the THz signals to the optical domain.

A low-noise, fast avalanche photodetector that operates in the 1,550 nm telecommunications band provides high sensitivity for data communications applications.

By using a single-quantum-well active region with a unique well–cladding design to suppress non-radiative recombination and enhance radiative recombination, light-emitting diodes with close to unity internal quantum efficiency at a low current density of <10⁻⁴ A cm⁻² are demonstrated.

A higher-order topological phase is demonstrated, manifesting as robust, topologically protected corner modes in a silicon photonics system.

Transduction of valley information to mechanical states in a monolayer MoS₂ resonator can be realized by optically pumping the valley carriers and applying an out-of-plane magnetic field gradient to induce a displacement-dependent valley splitting.

By time-shifting short-pulse excitation photon energy into prolonged luminescent emission in the time domain, both the number of light signal transducers in sub-15 nm nanoparticles and the near-infrared-in to near-infrared-out conversion efficiency can be maximized, advancing in vivo optical bioimaging.

It is possible to regulate random lasers by controlling and manipulating their properties, including the number and spatial positions of their lasing modes, and the lasing wavelength and the modal size over wide ranges. Performances comparable with non-random optical cavities with 2D photonic crystals are reported.

Organic phosphors with ultra-long lifetimes and an emission colour that can be tuned by the excitation wavelength are reported.

A phonon laser based on an optically levitated silica nanosphere is demonstrated. A lasing threshold—a phase transition from Brownian motion to coherent oscillation—is observed when the modulation depth of the trapping beam power is increased.

A hybrid technique of stimulated Raman excited fluorescence that integrates superb detection sensitivity and fine chemical specificity is demonstrated, offering all-far-field single-molecule Raman spectroscopy and imaging without plasmonic enhancement.

Spatially resolved spectra from millions of pixels and information extraction from three molecules per μm² is now possible using dielectric metasurfaces.

Net gain of ~10 dB µm^–1 and sub-picosecond switching time are shown at room temperature for optical transistors using polymers in a microcavity.

Nanometre thick metal films enable electrical tuning of plasmons.

Pre-shaping image wavefronts with random phase to locally reduce Fresnel diffraction to Fourier holography results in Fresnel holograms that form on-axis with full depth control without any crosstalk. This produces large-volume, high-density, dynamic 3D projections with 1,000 simultaneous image planes.

Optomechanical coupling enables an on-chip frequency comb and optical time-lens for 70-fold optical pulse compression.

The implementation of optically reassigned scanning laser ophthalmoscopy enables in vivo photon reassignment super-resolution imaging and high-resolution imaging of living human retinal cone photoreceptor cells without adaptive optics or chemical dilation of the eye.

By nesting a Kerr microresonator in a fibre loop with gain, 50-nm-wide bright microcavity-based soliton combs with a mode efficiency of 75% can be induced at average powers more than one order of magnitude lower than the Lugiato–Lefever soliton power threshold, facilitating real-world applications.

A nearly Fourier-limited X-ray free-electron laser beam is generated by a self-seeding scheme. The beam in the first half of the undulators is monochromatized via Bragg reflection, and is subsequently amplified in the remaining undulators.

Photoexcited charge carriers are typically approximated as a gas, but now it is shown that electrons and holes can behave as a liquid in MoTe₂ photocells.

Double-blind holography allows reconstruction of the missing spectral phases and characterization of the unknown signals in both isolated-pulse and double-pulse scenarios, facilitating the study of complex electron dynamics via a single-shot and linear measurement.