This article reviews recent progress leading to the generation of optical vortex beams. After introducing the basics of optical vortex beams and their promising applications, we summarized different approaches for optical vortex generation by discrete components and laser cavities. We place particular emphasis on the recent development of vortex generation by the planar phase plates, which are able to engineer a spiral phasefront via dynamic or geometric phase in nanoscale, and highlight the independent operation of these two different phases which leads to a multifunctional optical vortex beam generation and independent spin‐orbit interaction. We also introduced the recent progress on vortex lasing, including vortex beam generation from the output of bulk lasers by modification of conventional laser cavities with phase elements and from integrated on‐chip microlasers. Similar approaches are also applied to generate fractional vortex beams carrying fractional topological charge. The advanced technology and approaches on design and nanofabrications enable multiple vortex beams generation from a single device via multiplexing, multicasting, and vortex array, open up opportunities for applications on data processing, information encoding/decoding, communication and parallel data processing, and micromanipulations.

We propose to use a femtosecond direct laser writing technique to realize dielectric optical elements from photo-resist materials for the generation of structured light from purely geometrical phase transformations. This is illustrated by the fabrication and characterization of spin-to-orbital optical angular momentum couplers generating optical vortices of topological charge from 1 to 20. In addition, the technique is scalable and allows obtaining microscopic to macroscopic flat optics. These results thus demonstrate that direct 3D photopolymerization technology qualifies for the realization of spin-controlled geometric phase optical elements.

Because poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) is water processable, thermally stable, and highly conductive, PEDOT:PSS and its composites have been considered to be one of the most promising flexible thermoelectric materials. However, the PEDOT:PSS film prepared from its commercial aqueous dispersion usually has very low conductivity, thus cannot be directly utilized for TE applications. Here, a simple environmental friendly strategy via femtosecond laser irradiation without any chemical dopants and treatments was demonstrated. Under optimal conditions, the electrical conductivity of the treated film is increased to 803.1 S cm⁻¹ from 1.2 S cm⁻¹ around three order of magnitude higher, and the power factor is improved to 19.0 μW m⁻¹ K⁻², which is enhanced more than 200 times. The mechanism for such remarkable enhancement was attributed to the transition of the PEDOT chains from a coil to a linear or expanded coil conformation, reduction of the interplanar stacking distance, and the removal of insulating PSS with increasing the oxidation level of PEDOT, facilitating the charge transportation. This work presents an effective route for fabricating high‐performance flexible conductive polymer films and wearable thermoelectric devices.

Magnetic skyrmions are particle‐like topological magnetic textures that are potential information carriers in future spintronics. An enormous body of research confirms their existence in a broad range of magnetic materials since their first discovery in 2009. To date, magnetic skyrmions can not only be found in asymmetric systems but also in centrosymmetric ones. Notably, engineered magnetic multilayers are promising structures for skyrmion‐based spintronics because they can stabilize small‐sized skyrmions at room temperature and facilitate their electric manipulation. In this overview, we introduce the topological nature, their special properties, and nucleation methods of skyrmions, and show their potential for applications. Perspectives on skyrmionic devices and developments toward other, more three‐dimensional particle‐like magnetic nanostructures, are discussed at the end.

In this paper, WO₃-Pd₂Pt-Pt nanocomposite films were deposited on a single mode fiber as the hydrogen sensing material, which changes its reflectivity under different hydrogen concentration. The reflectivity variation was probed and converted to an electric signal by a pair of balanced InGaAs photoelectric detectors. In addition, the performance of the WO₃-Pd₂Pt-Pt composite film was investigated under different optical powers, and the irrigating power was optimized at 5 mW. With the irrigation of this optical power, the hydrogen sensitive film exhibits quick response toward 100 ppm hydrogen in air atmosphere at a room temperature of 25 °C. The experimental results demonstrate a high resolution at 5 parts per million (ppm) within a wide range from 100 to 5000 ppm in air. This simple and compact sensing system can detect hydrogen concentrations far below the explosion limit and provide early alert for hydrogen leakage, showing great potential in hydrogen-related applications.