Reviews & Analysis

A phase transition between disordered and quasi-ordered states, known as the Berezinskii–Kosterlitz–Thouless transition, has now been revealed in a two-dimensional photonic ‘fluid’. The interplay between phase singularities and coherence may lead to new vortex-based optical applications.

New methods to control how laser pulses propagate inside a plasma could signify the start of a global race to demonstrate truly high-energy compact particle accelerators.

The finding that hollow-core optical fibres can preserve the state of linearly polarized light over hundreds of metres with exceptional purity could benefit applications in sensing, gyroscopes and quantum optics.

Using a photonic chip to generate the patterns of light needed for structured illumination microscopy could reduce the cost and complexity of super-resolution imaging.

Optical clocks held at slightly different heights provide a stringent test of general relativity comparable to space experiments and open new opportunities for clock-based geophysical sensing.

A particular class of focused, pulsed light beams can propagate self-similarly in free space at a fixed group velocity. Now, scientists present a law of refraction that determines how the group velocity of these beams changes as they refract at an interface between two materials.

By utilizing exciton resonances in atomically thick semiconductors, researchers have now demonstrated the ultimate downscaling of optical lenses and reported on their efficacious electrical tunability.

Asymmetric forward and backward transmission through photonic structures can be achieved via optical nonlinearities, but existing systems have typically used slow thermo-optic effects. A new resonator design has now enabled low-loss, non-reciprocal pulse routing based on the Kerr nonlinearity in integrated silicon waveguides.

Advanced computational imaging techniques have the potential to extract neural activity patterns from scattered data without reconstructing images.

A monolithic chip-scale ring laser gyroscope based on both Brillouin and Sagnac effects provides a sensitivity sufficient to measure sinusoidal rotations with an amplitude as small as 5 degrees per hour, thus enabling the first on-chip Earth rotation measurement.

Using a photonic crystal slab combined with a conventional optical imaging system, a two-dimensional optical image differentiator is experimentally demonstrated for edge detection.

Dark-field microscopy is a widely used imaging method that emphasizes sharp edges and other small features, but typically requires specialized microscope components. Researchers have now engineered special substrates that enable dark-field microscopy using simple bright-field microscopes.

Exciton funnelling due to non-homogeneous strain was previously thought of as an efficient neutral exciton transport mechanism. New findings suggest that exciton funnelling might be negligible compared with another strain-dependent process, the conversion of neutral excitons into trions.

Two articles in Nature Photonics demonstrate how Einstein–Podolsky–Rosen entanglement can reduce quantum noise in gravitational-wave interferometers.

The news that superconducting nanowire detectors can detect single photons with a timing precision of just a few picoseconds will benefit applications ranging from sensing to quantum communications.

Low-loss composite systems based on integrating transition metal dichalcogenide monolayers on silicon nitride waveguides exhibit an unexpectedly strong electro-refractive response at near-infrared wavelengths, which is crucial for optical communications.