Volume 13 Issue 4, April 2019

The observation of a room-temperature stable liquid phase of electrons and holes in a quasi-two-dimensional photocell paves the way towards optoelectronic devices that harness collective phenomena.

By tailoring the anisotropy of light scattering along the surface of a macroscopic flat object, mechanical stabilization can be achieved without focused incident light or excessive constraints on the shape, size or material composition of the object.

A type of near-field curved light field generated right at the output of a dielectric cuboid is experimentally observed. It is expected to have interesting applications in imaging and manipulation.

The cost of infrared detectors has limited the deployment of multispectral imagers and sensors. Researchers now demonstrate simple quantum-dot devices that promise fast, sensitive and low-cost cameras that can switch between short- and mid-wavelength infrared.

This Review covers recent progress in AlGaN-based deep-ultraviolet light-emitting devices. The key technologies of how to improve their performance, carrier-injection efficiency, light extraction efficiency and heat dissipation are discussed.

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.

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.

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.

A laser-based scheme for the simultaneous generation of two temporally synchronized electron beams with individually adjustable energies offers new opportunities for ultrafast pump–probe experiments.

Eighty-five per cent absorptivity of unpolarized light over the wavelength range 300–2,500 nm is realized in a 90-nm-thick, 12.5 cm² metamaterial.

Colloidal quantum dot detectors, switchable between short-wave infrared and mid-wave infrared, are demonstrated.

Based on optically breaking time-reversal symmetry by spin polarizing a gain medium with a circularly polarized optical pump, an integrated scheme for controlling the chirality of orbital angular momentum lasing is demonstrated.

Mechanical stability of macroscopic structures on the millimetre-, centimetre- and even metre-scale could be realized by tailoring the anisotropy of light scattering along the object’s surface, without needing to focus incident light or excessively constrain the shape, size or material composition of the object.