In article number 2000338, Kseniia Baryshnikova, Sergey Makarov, and co-workers study a novel type of MAPbBr3 perovskite metasurface governed by overlapping the electric and magnetic Mie resonances in each meta-atom of the structure. They demonstrate both broadband suppression of reflection and photoluminescence enhancement, which are useful for many applications of nanostructured halide perovskites in photovoltaics and semi-transparent multifunctional metadevices.

Nanolasers are promising for applications in on-chip optical computing, optical interconnects, and high-resolution imaging. Two-dimensional materials are promising gain materials for designing of nanolasers. In article number 2000271, Wen Du, Jiang Wu, Zhiming Wang, and co-workers review the optical properties of 2D materials and the research progress in nanolasers based on 2D materials.

Optically stimulated luminescence (OSL) materials enable energy storage and then energy conversion to light upon photostimulation, with applications spanning from radiation dosimetry, optical data storage and security, environmental monitoring, biomedicine, clinical diagnostic, to archaeology and geology. In article number 2000123, Yahong Jin, Yihua Hu, Shihe Yang, and co-authors give a comprehensive review on the fundamental principle, design, preparation, characterization, optimization, research progress, application, mechanism, and prospect of OSL materials. The focus is placed on the discussion and summarization of trap engineering, study methodologies, the challenges, and outlooks.

Exciton intervalley scattering, annihilation, relaxation dynamics, and diffusive transport in monolayer transition metal dichalcogenides (TMDCs) are central to the functionality of devices based on them. In article number 2000029 by Jingyi Zhu, Paul H. M. van Loosdrecht, and co-workers investigate exciton-exciton annihilation dynamics and its effect in the distortion of the diffusion grating in an exfoliated monolayer TMDC, MoSe₂.

The luminescence properties of 2D materials, including graphene, transition metal dichalcogenides, black phosphorene, and topological insulators, are summarized. In addition, the research progress on different types of nanolasers based on 2D materials are reviewed, including microdisk lasers, microring lasers, photonic crystal lasers, and plasmonic lasers. Lastly, a conclusion and an outlook are given.

Optically stimulated luminescence (OSL) materials enable energy storage and energy conversion to light upon photostimulation. Here, a comprehensive review is provided on the fundamental principle, design, preparation, characterization, optimization, research progress, application, mechanism, and prospect of OSL materials. The focus is placed on the discussion and summarization of trap engineering, study methodologies, the challenges, and outlooks.

Due to the limitations manifested by conventional methods, machine learning approaches arise as powerful tools to enhance the reliability assessment and lifetime prediction of light-emitting diodes (LEDs) products with a better accuracy and faster computation. The future trend shows the emergence of digital twins through machine learning algorithms to simulate and analyze the performance behavior of LEDs.

The current advancements in the on-chip applications of Si photonics-2D materials heterostructures are reviewed and discussed, including all essential chip-scale modules and integrated photonic circuits, as well as the future prospective and challenges. This work sets out to objectively measure the feasibility of hybrid integration between Si photonics and 2D materials in on-chip optical communications and some advanced applications beyond.

The current state-of-the-art in microfluidic whispering gallery mode (WGM) resonators is reviewed. Different sensing mechanisms and various geometries of WGM cavities are described in detail. Moreover, the latest trends on the integration of WGM resonators with microfluidic devices are introduced. Finally, recent applications of microfluidic-based WGM sensors for detecting biological and chemical target molecules are discussed.

High-β metal-clad coaxial nanolasers, which facilitate thresholdless lasing are investigated with regard to their optical and quantum-optical properties. This joint experimental and theoretical work confirms that even a thresholdless laser does have a finite threshold pump power and must not be confused with a hypothetical zero-threshold laser. Moreover, the microscopic theory reveals an excitation power dependent β-factor of the nanolasers.

The generalized Kerker conditions are employed to overlap electric and magnetic Mie resonances in each meta-atom of MAPbBr₃ perovskite metasurface, and broadband suppression of reflection down to 4% is demonstrated. It is revealed that metasurface nanostructuring is also beneficial for the enhancement of photoluminescence. These results may be useful for applications of nanostructured halide perovskites in photovoltaics and semi-transparent multifunctional metadevices.

Exciton–exciton annihilation effect to both population and grating dynamics have been solved in exfoliated monolayer MoSe₂. Extremely fast intervalley scattering dynamics and much longer population lifetime of excitons are identified.

The hybrid optoplasmonic multi-level scheme of near-resonant interaction of laser pump and signal surface plasmon polariton with semiconductor quantum dots (QDs) placed in the proximity of a graphene surface is considered. The effect of the near-field light concentration in an array of QDs placed above the graphene is shown.

A nanoplate microcavity is utilized to realize robust polaritons in the strong-coupling regime. With an increase of the exciton density, the polaritons undergo a transition to Bose–Einstein condensation lasing. Its evolution presents the typical blue-shift, and its saturation behavior shows that the interaction strength, which is two orders of magnitude higher than reported values, is deduced from the renormalization.

The spontaneous emission intensity of plasmon-exciton polaritons can be revealed by ultrafast nonradiative decays, named as the nonradiative effect. This effect is not affected by the coherent energy exchange, because final states of nonradiative decays are decoupled from Rabi oscillations. Furthermore, the nonradiative effect is also established under intermediate coupling, which confirms its validity at a variety of coupling regimes.

A “meta-tip” optrode is proposed which integrates a plasmonic metasurface on the tip of an optical fiber, designed so as to impart a phase gradient that efficiently excites a surface wave. Via suitable biofunctionalization, the optrode can detect biomolecular (Biotin–Streptavidin) interactions in terms of wavelength shift in the reflectivity response. Results are of interest for real-time diagnosis via liquid biopsy.

Orbital angular momentum (OAM) carried by an elliptic Gaussian beam (EGB) with a cross-phase can induce an effective anisotropic diffraction. Such a phenomenon is experimentally demonstrated via propagations of the EGBs with OAM in linearly and both-linearly-and-nonlinearly isotropic media. In linear and nonlinear regimes, spiraling elliptic Gaussian modes and spiraling elliptic solitons are observed, respectively.

It is shown that the phase, polarization state and beam profile of the emission from evanescent waves can be efficiently manipulated by utilizing the electric and magnetic dipoles of a bianisotropic C-aperture metasurface. The results manifest a new paradigm for metasurfaces to work in the critical near-field region to harness the wealth of energy and information carried by evanescent waves.

A novel conditional variational autoencoder (CVAE) model for designing nanopatterned integrated photonic components is proposed. The prediction capability of the CVAE model can be significantly improved by adversarial censoring and active learning. Generation of nanopatterned power splitters with arbitrary splitting ratios and 550 nm broadband optical responses with >90% transmittance are demonstrated.