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Plasmons in metallic nanostructures provide light enhancement that amplifies their nonlinear optical response. This study shows that graphene nanoislands also give rise to an amplified nonlinear polarizability that can be tuned electrically to surpass those of other nonlinear media by orders of magnitude.

Rapid optical modulation is vital to many optoelectronic applications, like communications or imaging technologies. Here, the authors study the optical modulation of atomically thin gold nanodisks and find they have similar absorption cross-sections to spherical particles of the same width.

The authors present μeV electron spectromicroscopy, a technique that combines free-space light and electron beams to achieve unmatched spatial and spectral resolution. This approach enables detailed investigation of photonic structures, promising advancements in microscopy and quantum optics.

Despite the potential of free electrons for quantum technological applications, these are still limited by the weak electron-photon interactions. To address this challenge, the authors introduce electron-light couplers that produce high-photon-number state generation, enabling quantum sensing and metrology with unprecedented precision.

Nonreciprocal photonics often relies on the use of external magnetic fields. By combining atomistic simulations based on tight-binding with a mean-field approach, here, the authors demonstrate nonreciprocal plasmon propagation in electrically biased one-dimensional carbon nanostructures, including graphene nanoribbons and carbon nanotubes.

The authors propose wave-mixing cathodoluminescence, where laser-electron wave mixing in a nonlinear optical cavity upconverts low-frequency molecular resonances into visible photons, enabling nanoscale fingerprinting with visible light sources and detectors.

Graphene possesses a nonlinear optical response arising from its electronic dispersion. Here, the authors measure the response of graphene to an ultrafast optical field and provide an explanation of the quantum dynamics of Dirac carriers mediating the material’s nonlinear response.

The high-contrast dielectric boundary between a gold–air hybrid structure and its sharp spatial features are exploited to provide the momentum required for the excitation of higher-order hyperbolic phonon polaritons.

Propagating optical plasmons — collective electron excitations coupled to photons — are launched in graphene and studied with near-field optical microscopy, revealing ultra-strong optical field confinement and gate-tunable control of optical fields at nanoscale dimensions.

The intensity of optically-pumped fluorescence generated from a single atomic defect in diamond can be reduced by 80% in just 100 ns by applying infrared laser light. This result demonstrates the possibility of using these so-called nitrogen–vacancy centres to create optical switches that operate at room temperature.

Exploiting resonant quantum electron tunnelling empowered by an optically resonant, doubly periodic plasmonic nanowire metasurface, a biosensor with no external light source is demonstrated, boosting the integrability of the biosensor.

Existing approaches to modulating the properties of 2D materials typically involve heterostructuring or exposure to external fields. Here, the authors propose a gate-free non-contact approach to tuning the properties of a 2D semiconductor via the image interaction due to proximity to a neutral patterned structure.

Observations of collective electron waves in metal nanoparticles challenge our understanding of how light interacts with matter on small scales and underscore the need to factor quantum effects into nanophotonics. See Article p.421

Polaritonic topological transitions of the isofrequency dispersion contour are observed in a graphene/α-MoO₃ heterostructure by tuning the graphene doping level, which enables partial focusing at deep subwavelength.

An imaging technique has been demonstrated that blends the principles of conventional light and electron microscopy. It renders images with nanometre and femtosecond space-time resolution.

The authors have developed a custom-designed near-field probe to study the formation and emission characteristics of plexcitons arising from the interaction between surface plasmons in Au nanotrenches and excitons in monolayer WSe₂.

A single nitrogen-vacancy centre in a diamond nanocrystal can be trapped by optical tweezers and manipulated in all spatial directions.

The authors propose electron-positron creation by scattering of gamma-rays and polaritons, enabling the synthesis of ultrafast, localized positron sources and introducing the possibility to exploit nanophotonics for particle physics.

The authors demonstrate exciton-assisted resonant electron tunnelling in van der Waals heterostructure tunnel junctions. Their study elucidates tunnelling mechanisms involving either indirect or direct excitons in the absence of charge injection and reveals excitonic light emission driven by inelastic electron tunnelling.

High-harmonic generation is a nonlinear optical phenomenon that may be harnessed towards realisation of ultrafast light sources. Here, the authors theoretically show that localized plasmons in graphene nanodisks result in broadband and electrically tunable high-harmonic generation.

Graphene plasmons hold potential for infrared optoelectronic devices, but the interaction with the substrate often degrades their quality. Here, the authors report the characterization of plasmons in suspended graphene with tunable suspension height, showing enhanced quality factors and propagation lengths at room temperature.

Polaritons – hybrid light-matter excitations – in van der Waals materials hold promise for photonics applications below the diffraction limit. Here, the authors demonstrate in-plane steering and cloaking of phonon polaritons in assembled micro-structures based on α-MoO₃ films with misaligned crystallographic orientations.

Electron holography and microscopy have long been used to map static electric and magnetic fields. Here, authors establish Lorentz Microscopy of Optical Fields, a new technique that uses the deflection and interference of an electron beam to obtain phase-resolved images of nanoscale optical fields.

Current proposals suitable for experimental realization of topologically protected optical states rely on complicated structures or only operate in the microwave regime. Here, Pan et al. propose topological Dirac plasmons to be realized at infrared frequencies in a periodically patterned graphene monolayer, subject to a magnetic field of only 2 Tesla.

Planar growth of nanowire arrays involves interactions between materials that affect the electronic behavior of the effective heterojunction. Here, authors show how core curvature and cross-section morphology affect shell growth, demonstrating how strain at the core-shell interface induces electronic band modulations in ZnSe@ZnTe nanowires.

Graphene–insulator–metal heterostructures show three orders of magnitude enhancement of the third-harmonic generation with respect to the bare graphene case.

Electron relaxation, which is the dominant release channel of electronic heat in nanostructures, occurs with characteristic times of several picoseconds. Here, the authors predict that an ultrafast (femtosecond) radiative cooling regime takes place in plasmonically active neighboring graphene nanodisks prior to electron relaxation.

A system of patterned graphene nanoresonators/nanoribbons can be used as an efficient mid-infrared detector, based on plasmonic resonant absorption and subsequent carrier thermalization.

A Purcell factor as high as 10¹² is measured in atomically smooth nanocavities of hexagonal boron nitride nanotubes.

Free-electron homodyne detection allows measuring phase-resolved optical responses in electron microscopy, demonstrated in the imaging of plasmonic fields with few-nanometre spatial and sub-cycle temporal resolutions.

Manipulation of the electron–photon coupling is crucial for quantum circuits and exploration of electronic motions and nuclear phenomena. Here the authors discuss a scheme to coherently control the electron wave function from attosecond to zeptosecond timescales by using semi-infinite light fields.

Visualizing surface plasmon polaritons at buried interfaces has remained elusive. Here, the authors develop a methodology to study the spatiotemporal evolution of buried near-fields within complex heterostructures, enabling the characterization of the next generation of plasmonic devices.

It is possible to modify the electronic structure of a naturally patterned gold surface in potentially useful ways by allowing layers of silver or copper atoms to self-assemble into arrays of nanostructures.

Silicon is a popular material for solar cells, but is poor at absorbing infrared light, wasting much of this part of the solar spectrum. Here, Garin et al.show an efficient infrared photoresponse in nanometre-scale silicon spheres based on the resonant scattering of light that increases the dwelling time of light.

Tunable X-ray generation, from ultrathin van der Waals materials impacted by relativistic electrons, is demonstrated.

Identification of gas molecules is crucial in healthcare and security applications. Here the authors achieve label-free identification of SO₂, NO₂, N₂O, and NO gas molecules by detecting their rotational-vibrational modes using graphene nanoribbon plasmons.

Monochromatic electron energy-loss spectroscopy enables the observation of highly confined and ultraslow hyperbolic phonon polaritons in suspended monolayer hexagonal boron nitride, expanding the potential of van der Waals materials for nanophotonic applications.

Nanometre thick metal films enable electrical tuning of plasmons.

This work studies luminescence from monocrystalline gold flakes down to 13 nm thick. It reveals this signal is photoluminescence, with signals reproduced by density functional theory, resolving a decade-old puzzle.

Free-electron decoherence produced by electron coupling to radiation constitutes a quantum-physics macroscopic phenomenon that enables nondestructive sensing of distant objects

Semimetal photodetectors provide high-speed and broadband operation but suffer from serious drawbacks such as high dark currents. This Perspective discusses the opportunities offered by topological effects to overcome these issues and improve their performance.

Photoemission from nanostructures has raised considerable interest in recent years. The authors propose a low-budget scheme for multiphoton photemission with a continuous-wave laser that may inspire design of accessible nanoscale coherent electron sources.