Optics and photonics

A multiscale modelling platform combining nanoscale resonant scattering, mesoscale multiple scattering and macroscale light transport effectively predicts the macroscopic visual effects created by optical metamaterials with disordered nanostructures.

The morphology of donor–acceptor blends in organic photovoltaics dictates the efficiency of the exciton dissociation and charge diffusion, and thus the final device performance. Here, the authors show that filament assembly helps to maximize the output, further enabling a power conversion efficiency greater than 19%.

Departing from common approaches to designing Floquet topological insulators, here the authors present a photonic realization of Floquet topological insulators revealing topological phases that simultaneously support Chern and anomalous topological states.

Cu₂O is a promising platform to host Rydberg exciton–polaritons, where excitons strongly couple to cavity photons, however their realization has been elusive. Here, the authors report Rydberg exciton–polaritons with principal quantum numbers up to n = 6.

Measuring three-dimensional dielectric tensors is desired for applications in material and soft matter physics. Here, the authors use a tomographic approach and inversely solve the vectorial wave equation to directly reconstruct dielectric tensors of anisotropic structures.

Controlled synthesis of heterostructured III-V–II-VI nanocrystals shows that dipole moments formed at the core–shell interface can tune the optoelectronic properties of these nanomaterials and their performance in light-emitting devices.

The large-scale fabrication of cellulose nanocrystal photonic films in a roll-to-roll device is achieved by careful optimization of the cellulose nanocrystal formulation and its controlled deposition and drying on a substrate. Once dry, these photonic films can be peeled and milled into effect pigments, highlighting the potential of cellulose nanocrystals as a sustainable material for industrial photonic applications.

Tamm plasmon thermal emitters can provide low-cost, efficient mid to long infrared emission, but have been limited by a challenging design. Here the authors apply an inverse design protocol to demonstrate tailorable multi-band emission on CdO films.

A strategy to confine phosphorescent organic chromophores within ionic crystals proves effective in suppressing non-radiative recombination channels and increasing the phosphorescence efficiency of blue-emitting heavy-atom-free emitters.

An outlook on the potential of lead-halide perovskites as a playground for exciton-polariton studies and for the development of polaritonic devices operating at room temperature is provided.

This Review focuses on nonlinear electromagnetic responses that arise from quantum geometry and topology.

This Review discusses the photophysical properties and nonlinear behaviour of single molecules, and their use as single-photon sources and in single-molecule sensing and quantum-sensing applications.

Stacked elastomeric arrays containing plasmonic nanoparticles show efficient chiral responses that can be fully controlled by mechanical compression and stack rotation. These simple layered materials may be useful modulators for photonic applications.

Strong exciton–polariton coupling is leveraged as a means to open up phonon scattering channels that are otherwise weak.

The optical emission of graphene under pumping with femtosecond laser pulses contains a strong component linked to plasmon emission from the hot electrons in the system.

Raman measurements of twisted bilayer MoS₂ as a function of twist angles, with theoretical support, reveal phonon renormalization in this moiré superlattice.

Vertical organic light-emitting transistors are realized by using a porous base electrode in the centre of the device, which improves efficiency and reduces operating voltage by regulating charge transport and forming an optical microcavity.

A second-order topological Weyl semimetal based on a 3D-printed acoustic crystal, exhibiting Weyl points, Fermi arc surface states, and hinge states, has been experimentally demonstrated.

Non-thermal lattice control of exchange interactions allows for picosecond coherent switching between competing antiferromagnetic and weakly ferromagnetic order.

The moiré pattern that is formed between well-aligned graphene and hexagonal boron nitride can modify the properties of WSe₂ (placed close by without intentional angle alignment), leading to the formation of a mini Brillouin zone and the folding of the bands in WSe₂.

The development of perovskite emitters, their use in light-emitting devices, and the challenges in enhancing the efficiency and stability, as well as reducing the potential toxicity of this technology are discussed in this Review.

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.

Thermoplasmonics is based on the use of plasmonic nanoparticles as sources of heat remotely controlled by light. This Review discusses its current applications and challenges in a broad range of scientific fields, from nanomedicine to hot-electron chemistry and nanofluidics.

Photo-excited gold nanoparticles are shown to provide ultrafast and efficient hot-hole injection to the valence band of p-type GaN, substantially altering hot-electron dynamics in the nanoparticles and forming a basis to design hot-hole-based optoelectronics.

The integration of barium titanate thin films with silicon-based waveguides enables the operation of efficient electro-optic switches and modulators at temperatures as low as 4 K, with potential applications in quantum computing and cryogenic computing technologies.

An investigation on the electronic transitions of organic radicals allows us to identify design rules to increase the oscillator strength of these emitters and obtain efficient radical-based light-emitting diodes operating in the visible range.

The use of rigid linkers to control the relative position and interaction of donor and acceptor units in exciplex emitters leads to the realization of organic light-emitting devices with enhanced external quantum efficiency.

A spatially resolved optical polarimetry technique is used to identify a three-state Potts-nematic order parameter in a triangular lattice antiferromagnetic material.

Repulsive dipole–dipole interactions between localized interlayer excitons are shown to modify the optical response of van der Waals heterobilayers, forming the basis to obtain strong optical nonlinearity and excitonic many-body states in two-dimensional materials.

The spectral range of long-lived and confined phonon polaritons in a polar van der Waals crystal is shown to be tunable by intercalation of Na atoms, expanding their potential for nanophotonic applications in the mid-infrared domain.

Electric-field tunable plasmonic excitations in semiconducting carbon nanotubes are shown to behave consistently with the nonlinear Luttinger liquid theory, providing a platform to study non-conventional one-dimensional electron dynamics and realize integrated nanophotonic devices.

Counter-propagating chiral edge states are demonstrated in a photonic structure able to effectively incorporate fermionic time-reversal symmetry, thus providing the photonic implementation of an electronic topological insulator.

Vectorial electromagnetic modes in coupled metallic nanolasers are used to emulate the behaviour of complex magnetic materials, providing an integrated nanophotonic platform to study spin exchange interactions and map large-scale optimization problems.

Structurally pure cubic ice Ic is obtained from the controlled heating of D₂O ice XVII.

Type-II van der Waals interfaces formed by different two-dimensional materials enable robust interlayer optical transitions, regardless of common issues such as lattice constant mismatch, layer misalignment or whether the constituent compounds are direct or indirect band semiconductors.

Multiple layers of diamond-like carbon films are shown to act as moisture barriers when conformally deposited on carbon fibre reinforced polymers used in space applications.

The ultrafast response of a pyroelectric sensor with near-infrared responsivity is demonstrated by combining a pyroelectric thermal detector with wavelength-selective nanoparticle absorbers.

Repetitive electrical pulse stimulation of blue-phase liquid crystals promotes their reconfiguration into stable non-cubic structures with promising electro-optical responses for display technologies.

Water clusters induce hole traps in organic semiconductor thin films. Detrimental effects of hole and electron traps on charge transport can be avoided by using materials with ionization energy and electron affinity within an energy window of 2.4 eV.

Plasmonic array nanolasers with Yb³⁺/Er³⁺-co-doped upconverting nanoparticles exhibit directional single-mode emission, with ultra-stable output over hours and with ultralow-threshold under continuous-wave pumping.

Due to the crystal symmetry of single-layer transition metal dichalcogenides and the fact that the conduction and valence band edges are at the zone-edge K points, the 2p exciton states are split. A two-colour pump–probe scheme is used to drive the 1s–2p exciton transition, and then probe the changes in absorption near the spectral position of the 1s line to measure the splitting energy.

Spatially resolved electron microscopy techniques, such as cathodoluminescence and electron energy-loss spectroscopy can provide high space, energy and time resolutions for the structural and optical characterization of materials; this Review discusses recent progress and future directions in the field of nanophotonics.

A spatially dispersive photoresponse is found in a topological semimetal.

Local tuning of quantum dots embedded in a photonic waveguide can be achieved through the strain produced by laser heating of a thin layer of HfO₂ deposited around the waveguide. The method is exploited to tune three quantum dots in resonance.

Low-dimensional tin-halide perovskites exhibit strong temperature dependence of luminescence decay time that translates into high sensitivity over a wide range of temperatures and as such can be used in high-resolution remote thermography.

This Review covers the basic physics of thermal emission, ways to engineer the thermal field radiated by hot objects in the far field and applications, such as thermophotovoltaics, radiative cooling, camouflage and privacy.

The droplet epitaxy technique has emerged as an alternative to the most commonly used Stranski–Krastanov for fabricating semiconductor nanostructures. This Review discusses the important aspects of droplet epitaxy quantum dots, from the growth mechanism to device application.

By exciting chiral plasmons within a nanohole by means of circularly polarized light pulses, orbital angular momentum can be imparted onto charged matter waves (here, electrons) and controlled at terahertz speed (femtosecond intervals).

The remote, non-volatile and reversible optical control of ferroic orders is challenging. Here, using laser illumination, multiple orders in epitaxial mixed-phase BiFeO₃ are manipulated deterministically using a thermally driven flexoelectric effect.