Volume 15 Issue 8, August 2021

Reducing the footprint of optical spectrometers is a critical requirement for many in-field applications. Now, a single black phosphorus photodetector with a wavelength-scale size enables mid-infrared computational spectrometry.

A ‘twin-field’ repeater-less protocol has enabled an experimental demonstration of secure quantum key distribution over a 511-km long-haul optical fibre link.

The adiabatic encirclement of exceptional points in non-Hermitian systems is known to produce surprising non-adiabatic effects. A new study finds a cheat code to exactly emulate this behaviour without ever having to produce an exceptional point.

Recent progress in terahertz scanning probe microscopy is reviewed with an emphasis on techniques that access length scales below 100 nm relevant to material science. An outlook on the future of nanoscale terahertz scanning probe microscopy is also provided.

A field test of twin-field quantum key distribution was implemented through a 511 km optical fibre. To this end, precise wavelength control of remote independent laser sources and fast time- and phase-compensation systems are developed.

Experimental and theoretical results of wave propagation in a disordered system with non-Hermitian disorder are presented, showing that wave spreading occurs in the parameter regime where all eigenstates are expected to be localized.

Researchers coupled exciton–polariton modes to one another in a six-fold symmetric microcavity with loss manipulation and observed room-temperature polaritonic parity-time-reversal symmetry.

An optically synchronized precision fibre link based on two independent chip-scale cavity-stabilized stimulated Brillouin scattering lasers is demonstrated. An ultralow 3 × 10⁻⁴ rad² residual phase error variance is achieved between the mutually coherent transmit and receive lasers.

Subcycle nano-videography of charge-transfer dynamics in WSe₂/WS₂ heterostructures is obtained by using a terahertz near-field microscopy. The central idea is to probe the local polarizability of electron–hole pairs with evanescent terahertz fields.

A single-photodetector spectrometer based on black phosphorus is demonstrated in the wavelength range from 2 to 9 μm. The footprint is 9 × 16 μm². The spectrometer is free from bulky interferometers and gratings, and is electrically reconfigurable.

The second-harmonic spatiotemporal orbital angular momentum of an optical pulse and its space–time topological charge conservation during frequency doubling are experimentally observed, opening opportunities for nonlinear conversion and scaling of photons carrying spatiotemporal orbital angular momentum.

Mid-infrared polarization detectors based on nanoantenna-mediated few-layer graphene are demonstrated. By tuning the orientation of nanoantennas, the polarization ratios vary from positive to negative, and cover values from 1 to ∞/−∞ then to −1.

Structured beams of light are used to engineer conduction band populations and pattern currents. Using the approach, dynamic optoelectronic interconnects and other applications are demonstrated.