Phys.org October 11, 2023 Orbital angular momentum (OAM) generators based on metasurfaces can achieve ultracompact designs. However, they generally have limited working bandwidth and require complex designs and multistep time-consuming fabrication processes. Researchers in Australia designed broadband graphene OAM metalenses with flexibly controlled topological charges using the detour phase method and fabricated using ultrafast laser nanoprinting. The experimental results agreed well with the theoretical predictions, which demonstrated the accuracy of the design method. The broadband graphene OAM metalenses have broad applications in miniaturized and integrated photonic devices enabled by OAM beams… read more. Open Access TECHNICAL ARTICLE
Tag Archives: S&T Australia
Mapping Australia’s hidden lithium reserves
Phys.org August 31, 2023 Researchers in Australia used a digital soil mapping framework to combine data from recent geochemical surveys and environmental covariates that affect soil formation to predict and map aqua-regia-extractable Li content across the 7.6×106 km2 area of Australia. Catchment outlet sediment samples were collected with both top (0–10 cm depth) and bottom (on average ∼60–80 cm depth). They developed 50 bootstrap models using a cubist regression tree algorithm for each depth. The spatial prediction models were validated on an independent Northern Australia Geochemical Survey dataset, showing a good prediction for the top depth. The model for the bottom depth is […]
‘Topological gardening’ to achieve unexpected spin transport
Nanowerk August 22, 2023 In topological materials the interaction between the bulk state and edge states can be tuned to manipulate edge transport behavior, especially in topological crystalline insulators (TCI) which have multiple degrees of topological protection. This can open opportunities for novel electronic and spintronic applications. Researchers in Australia investigated how bulk-edge interactions can influence the edge transport in planar bismuthene, a TCI with metallic edge states protected by in-plane mirror symmetry. By exploring the impact of various perturbation effects, such as device size, substrate potentials, and applied transverse electric field, they examined the evolution of the electronic structure […]
New-look infrared lens shines a light on future technology and manufacturing
Phys.org May 29, 2023 There is a need for low-cost alternatives to traditional materials used in infrared optics such as germanium. Sulfur-rich copolymers hold promise, as they are made from low-cost feedstocks and have a high refractive index. Researchers in Australia copolymerized cyclopentadiene with sulfur to provide a plastic with the highest long-wave infrared transparency reported to date for this class of materials. Diverse lens architectures were accessible through melt casting or reactive injection molding. The featured copolymer was black, which enabled its use as an infrared-transparent blind for protection of thermal imaging equipment and clandestine surveillance. According to the […]
Half-century of cyclone data puts researchers on track to explore future risks
Phys.org January 19, 2023 Tropical cyclones (TCs) with genesis in the Coral Sea present significant hazards to coastal regions in their surroundings. In addition, the erratic nature of TC tracks is not well understood in this region. Researchers in Australia grouped Coral Sea TC tracks over the last fifty years based on K-means clustering of the maximum wind-weighted centroids to extract valuable new cyclone power, track curvature and location related information to predict their behaviour. They assessed the TC track variance and curvature (sinuosity) and identified three well-defined clusters of TC tracks. The results showed differing predominant directions of TC […]
New nanowire sensors are the next step in the Internet of Things
Phys.og January 6, 2023 Despite intensive research and rapid progress in self-powered gas devices, most reported devices, specifically NO2 sensors for air pollution monitoring, have limited sensitivity, selectivity, and scalability. Researchers in Australia have demonstrated a photovoltaic self-powered NO2 sensor based on axial p–i–n homojunction InP nanowire (NW) arrays, that overcame these limitations. The device was designed by numerical simulation for insights into sensing mechanisms and performance enhancement. Without a power source, the InP NW sensor achieved an 84% sensing response to 1 ppm NO2 and recorded a limit of detection down to the sub-ppb level, with little dependence on […]
Meta-optics: The disruptive technology you didn’t see coming
Phys.org December 22, 2022 Optical metasurfaces interact strongly with light. The field has been driven by the key advantages of this concept, including the ultimate miniaturization of optical elements, empowering novel functionalities that process hidden modalities of light, and the opportunity to tune their properties on demand. Many applications with a focus on smart vision have emerged, foreseeing a meta-optical device under the hood of any robotic system. Nowadays the field is experiencing a solid industry pull that defines the challenges and research directions. In this review researchers in Australia have provided an overview of the applications of the field […]
Ammonium is the secret ingredient in stable, efficient & scalable perovskite solar cells
EurekAlert December 20, 2022 Controlling the crystallization process of perovskite thin films to obtain a high-quality material is one of the most challenging aspects for upscaling perovskite solar cell (PSC) technology. However, to date, lead acetate has been used exclusively as a precursor for the synthesis of methylammonium (MA) or cesium (Cs) based perovskites, which are unstable and less efficient. Researchers in Australia produced high-quality large-area formamidinium–caesium mixed-cation perovskite films by blade-coating a lead acetate-based precursor formulation in an ambient laboratory environment, with the use of NH4+ as a volatile cation to drive off acetate during annealing, leading to formation […]
New kind of tropical cyclone identified in the Indian Ocean
Phys.org November 28, 2022 Researchers in Australia focused on the regional wind variability that controls the intensity of cold-water upwelling off Sumatra – a key feature of the Indian Ocean Dipole (IOD). Their analysis of daily atmospheric data revealed the existence of convectively triggered synoptic-scale atmospheric cyclones in the South-East Tropical Indian Ocean (SETIO). The northern branch of the cyclones corresponded to westerly equatorial wind events, whereas the eastern branch involved north-westerly winds that operate to suppress cold-water upwelling off Sumatra’s west coast. Data for the period 1988–2022 showed that 5–9 SETIO cyclones normally form each year during the boreal […]
New communications technology: Super-fast optical lasers
Science Daily November 9, 2022 While enabling orders-of-magnitude gains in data rates, optical signals impose much stricter pointing requirements and are strongly affected by atmospheric turbulence. Researchers in Australia established a coherent 1550 nm link across turbulent atmosphere between a deployable optical terminal and a drone-mounted retroreflector. Through 10 Hz machine vision optical tracking with nested 200 Hz tip/tilt adaptive optics stabilisation, they corrected for pointing errors and atmospheric turbulence to maintain robust single mode fiber coupling, resulting in an uninterrupted 100 Gbps optical data link while tracking at angular rates of up to 1.5 deg/s, equivalent to that of […]