In this Letter, we propose an approach to generate high-purity orbital angular momentum (OAM) vortex waves using an amplitude-and-phase metasurface (APM). By varying the square split ring opening and orientation angles, the cross-polarized reflection response of the proposed structure can yield full phase and amplitude coverage. Based on the traditional phase-only metasurface (POM), the Chebyshev synthesis method (CSM) is applied to array the metasurface amplitude distribution. Metasurfaces with modes of 1, 2, 3, and 4 are designed. Compared with the POM, the APM can effectively improve the vortex beam quality and OAM mode purity. The measured results agree well with full-wave simulations. The presented method provides a new, to the best of our knowledge, way to design high-purity OAM generators based on metasurfaces.
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http://dx.doi.org/10.1364/OL.441426 | DOI Listing |
Adv Mater
December 2024
Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA, 91125, USA.
High temperatures promote kinetic processes that can drive crystal synthesis toward ideal thermodynamic conditions, thereby realizing samples of superior quality. While accessing very high temperatures in thin-film epitaxy is becoming increasingly accessible through laser-based heating methods, demonstrations of such utility are still emerging. The study realizes a novel self-regulated growth mode in the Ti-O system by relying on thermally activated diffusion of oxygen from an oxide substrate.
View Article and Find Full Text PDFLight beams carrying orbital angular momentum (OAM) in free space or within optical fibers have a wide range of applications in optics; however, exciting these modes with both high purity and low loss generally requires demanding optimization of excitation conditions in a high dimensional space. Furthermore, mechanical drift can significantly degrade the mode purity over time, which may limit practical deployment of OAM modes in concrete applications. Here, combining an iterative wavefront matching approach and a genetic algorithm, we demonstrate rapid and automated excitation of OAM modes with optimized purity and reduced loss.
View Article and Find Full Text PDFSci Bull (Beijing)
December 2024
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China. Electronic address:
Water has been detected in lunar regolith, with multiple sources identified through the analysis of individual grains. However, the primary origin of water in the bulk lunar regolith remains uncertain. This study presents spectroscopic analyses of water content in sealed Chang'e-5 samples.
View Article and Find Full Text PDFJ Colloid Interface Sci
October 2024
Laboratory of Solar Fuel, Faculty of Materials Science and Chemistry, China University of Geosciences, 68 Jincheng Street, Wuhan 430078, China. Electronic address:
Chlorine evolution reaction (CER) is crucial for industrial-scale production of high-purity Cl. Despite the development of classical dimensionally stable anodes to enhance CER efficiency, the competitive oxygen evolution reaction (OER) remains a barrier to achieving high Cl selectivity. Herein, a binder-free electrode, Ru nanoparticles (NPs)-decorated NiMoO nanorod arrays (NRAs) supported on Ti foam (Ru-NiMoO/Ti), was designed for active CER in saturated NaCl solution (pH = 2).
View Article and Find Full Text PDFInorg Chem
June 2024
Department for Hydrogen Technology, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway.
Large quantities of high-purity NHCrF have been synthesized using a wet-chemical method, and its structural chemistry and magnetic properties are investigated in detail for the first time. NHCrF is a tetragonal fluoroperovskite that displays an ordering of the ammonium (NH) groups at room temperature and C-type orbital ordering. The ammonium groups order and display distinct signs of hydrogen bonds to nearby fluoride anions by buckling the Cr-F-Cr angle away from 180°.
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