Volume 14 Issue 7, July 2020

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.

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.

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.

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.

A pair of transportable optical lattice clocks with 10⁻¹⁸ uncertainty is developed. The relativistic redshift predicted by the theory of general relativity has been tested at the 10^–5 level by the two optical clocks with a height difference of 450 m on the ground.

An appropriately designed pulsed beam crossing an interface is shown to enable phenomena including anomalous group-velocity increase in higher-index materials, and tunable group velocity by varying the angle of incidence.

Phase-matching quantum key distribution is implemented with a 502 km ultralow-loss optical fibre. The fluctuations of the laser initial phases and frequencies are suppressed by the laser injection technique and the phase post-compensation method.

By harnessing the excitonic resonances of a monolayer of WS₂ in the visible spectral range, large-area, actively tunable and atomically thin optical lenses can be realized.

The use of a photonic integrated circuit to both hold a biological sample and generate the necessary light patterns for structured illumination microscopy promises convenient super-resolution imaging.

Transscleral optical phase imaging, which is based on transscleral flood illumination of the retina, is demonstrated to provide cellular-resolution, label-free, high-contrast images of the retinal layers over a large field of view without the drawback of a long exposure time.

Robust terahertz wave transport is demonstrated on a silicon chip using the valley Hall topological phase. Error-free communication is achieved at a data rate of 11 Gbit s⁻¹, enabling real-time transmission of uncompressed 4K high-definition video.

The incorporation of microsphere lasers into heart cells allows all-optical recording of cardiac contraction with cellular resolution. [This summary has been amended from ‘microdisk’ to ‘microsphere’ lasers.]