Negative refraction, an unnatural optical phenomenon in which the incident and the refracted waves reside on the same side of the surface normal, has been demonstrated with the invention of negative index media based on artificially engineered photonic structures called metamaterials. It has received wide attention due to its potential applications in imaging, nonlinear optics, and electromagnetic cloaking. However, it is highly challenging to realize negative refraction operating at all angles and with the perfect transmission. In this work, leveraging the recent development in topological photonics, we propose to realize reflectionless negative refraction for all incident angles with a topological metamaterial. The proposed metamaterial possesses two Weyl points of opposite topological charges. By interfacing the metamaterial with a perfect electric conductor (PEC) or a perfect magnetic conductor (PMC), the Fermi arc connecting the two Weyl points can take the form of a half-circle possessing a positive or a negative refractive index. Importantly, due to the topological protection, there is no reflection at the interface between the PEC and PMC covered areas, leading to the observation of all-angle negative refraction without reflection at the boundary. Our work provides a new platform for manipulating the propagation of surface waves, which may find applications in the construction of integrated photonic devices.
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http://dx.doi.org/10.1038/s41377-022-00972-9 | DOI Listing |
Nanophotonics
January 2025
MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering Tongji University, Shanghai 200092, China.
The formed optical cavity mode intensively relies on the size and geometry of optical cavity. When the defect or impurity exists inside the cavity, the formed cavity mode will be destroyed. Here, we propose a metacavity consisting of arrays of linear-crossing metamaterials (LCMMs) with abnormal dispersion, where each LCMM offers both the directional propagation channel for all incident angles and the negative refraction across its neighboring LCMMs.
View Article and Find Full Text PDFJ Ophthalmol
January 2025
Pediatric Ophthalmology, Shanxi Aier Eye Hospital, Aier Eye Hospital Group, Changsha, China.
To investigate the correlation between corneal biomechanical characteristics and refractive status in adolescents aged 5-13 years. A cross-sectional study involved 339 children aged 5-13 with a spherical equivalent (SE) range from -6.00 to +2.
View Article and Find Full Text PDFQuant Imaging Med Surg
January 2025
Aier Institute of Refractive Surgery, Refractive Surgery Center, Guangzhou Aier Eye Hospital, Guangzhou, China.
Background: Whether the correlations between anterior and posterior corneal parameters vary according to different conditions is unknown. We aimed to investigate the anterior-to-posterior correlations of corneal parameters according to different refractive status and anterior segment dimension.
Methods: A total of 8,365 myopic eyes undergoing refractive surgery between 2017 and 2019 from multiple ophthalmic centers were consecutively included in the study.
Ophthalmol Ther
January 2025
Eye School of Chengdu, University of Traditional Medicine, Chengdu, 510100, Sichuan Province, China.
Introduction: This study aimed to compare changes in retinal oxygen saturation 1 month after femtosecond-assisted laser in situ keratomileusis (FS-LASIK) in Chinese adults with myopia using retinal oximetry.
Methods: In this prospective, observational, single-center cohort study, Chinese adults aged 18-45 years with myopia were categorized into four groups according to spherical equivalent (SE), with 66 eyes characterized as low myopia (LM -3.00D < SE ≤ -0.
Front Ophthalmol (Lausanne)
January 2025
Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Background: The pathophysiologic mechanisms underlying early-onset myopia remain unclear; in this study, we investigate the pathogenesis by examining the interrelationships between axial length to corneal curvature radius ratio ( ) and choroidal blood flow.
Methods: This cross-sectional study included 202 eyes from myopic children, categorized into 141 eyes with mild myopia, 47 eyes with moderate myopia, and 14 eyes with high myopia. Optical coherence tomography angiography (OCTA) was used to measure choroidal blood flow perfusion within a 6 mm × 6 mm area of the macular region, divided into nine subareas based on ETDRS partitioning: macular fovea, nasal side 1, superior 1, temporal side 1, inferior 1, nasal side 2, superior 2, temporal side 2, and inferior 2.
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