Articles in 2020

Research activities in the areas of X-ray imaging and ultraviolet sterilization illustrate how photonics is helping to combat the threat of COVID-19.

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.

By suppressing the second- and third-order intracavity dispersion using an intracavity spectral pulse shaper, a mode-locked laser that emits pure-quartic soliton pulses that arise from the interaction of the fourth-order dispersion and the Kerr nonlinearity is demonstrated.

The first operation of the European X-ray free-electron laser facility accelerator based on superconducting technology is reported. The maximum electron energy is 17.5 GeV. A laser average power of 6 W is achieved at a photon energy of 9.3 keV.

Highly sensitive avalanche photodiodes that operate at near-infrared wavelengths of up to 2 μm could prove useful for eye-safe light imaging, detection and ranging, and other applications.

Carefully designed hollow-core antiresonant fibres support a pair of orthogonal polarization modes with a level of purity and cross-coupling that is orders of magnitude lower than other fibre designs and beyond the fundamental Rayleigh scattering limit of glass core fibres.

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.

Combining the advantages of ultrasound and light for fluorescence imaging, an imaging technique termed fluorescence and ultrasound-modulated light correlation, or FLUX, that leverages the dynamic nature of the medium is reported to uniquely resolve fluorophore distribution even when the speckles decorrelate fast.

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

Delegates at the BiOS symposium heard how artificial intelligence can transform medical imaging, with its ability to improve quality, speed and molecular specificity.

Integrated quantum photonic chips offer the promise of a convenient, scalable platform for performing tasks such as quantum communication and information processing.

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.

A metasurface laser generates orbital angular momentum states with quantum numbers reaching ℓ = 100. Simultaneous output vortex beams, with Δℓ as great as 90, are demonstrated in the visible regime.

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.