- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Topological strong-field physics on sub-laser-cycle timescale
摘要： The sub-laser-cycle timescale of the electronic response to strong fields enables attosecond dynamical imaging in atoms, molecules and solids, with optical tunnelling and high-harmonic generation the hallmarks of attosecond optical spectroscopy. Topological insulators are intimately linked with electron dynamics, as manifested via the chiral edge currents, but it is unclear if and how topology leaves its mark on optical tunnelling and sub-cycle electronic response. Here, we identify distinct bulk topological effects on directionality and timing of currents arising during electron injection into conduction bands. We show that electrons tunnel differently in trivial and topological insulators, for the same band structure, and identify the key role of the Berry curvature in this process. These effects map onto topologically dependent attosecond delays and helicities of emitted harmonics that record the phase diagram of the system. Our findings create new roadmaps in studies of topological systems, building on the ubiquitous properties of the sub-laser-cycle strong-field response—a unique mark of attosecond science.
关键词： high-harmonic generation,attosecond science,Berry curvature,topological insulators,strong-field physics
更新于2025-09-12 10:27:22
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55.1: <i>Invited Paper:</i> Achieving high uniformity of 200 mm GaN‐on‐Si LED epiwafers for micro LED applications
摘要： One of the big challenges of micro LED displays is to reduce cost/increase yield and establish excellent manufacturability. Galliumnitride on silicon (GaN-on-Si) LED epiwafers offer fundamental cost advantages to the entire process flow for micro LEDs compared with conventional GaN-on-sapphire LED epiwafers. However, due to the difficulties of epitaxial growth of GaN-on-Si, demonstration of such cost advantages in micro LED application is not wide-spread yet. In this presentation, we have demonstrated excellent emission uniformity with well- controlled strain by precise strain-engineering. This opens the way to use the advantages of GaN-on-Si LED epiwafers in the entire supply chain of micro LED making and thus reduce cost significantly and enable high yield manufacturing.
关键词： curvature,GaN-on-Si,200 mm epiwafer,reproducibility,micro LED,emission wavelength uniformity,strain-engineering
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Phase Dislocations in the Negative Curvature Hollow Core Fibres
摘要： The negative curvature hollow core fibres (NCHCFs) have attracted recently a great deal of attention because of their potential for many practical applications ranging from optical communications to high power lasers and power delivery. In the NCHCFs light is strongly localized in the air core due to the mode field interaction with the limited portions of the core-cladding boundary. In our work we observed that the light leakage from the hollow core in NCHCFs has features which indicate the formation of phase dislocations and optical vortices in the cladding elements. Here we demonstrate that there are lines in the cladding capillary walls along which the imaginary and real parts of the transverse components of the core mode electric field Ex and Ey are equal to zero and can cross each other (the zero – amplitude lines). The direction of the transverse component of the core mode electric field is uncertain in the vicinity of these lines. Such behaviour of the core mode fields and its polarization indicates the presence of optical vortices in the cladding capillary wall.
关键词： negative curvature hollow core fibres,cladding capillary walls,phase dislocations,optical vortices
更新于2025-09-11 14:15:04
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Optically Controlled Orbitronics on a Triangular Lattice
摘要： The propagation of electrons in an orbital multiplet dispersing on a lattice can support anomalous transport phenomena deriving from an orbitally induced Berry curvature. In striking contrast to the related situation in graphene, we find that anomalous transport for an L ? 1 multiplet on the primitive 2D triangular lattice is activated by easily implemented on site and optically tunable potentials. We demonstrate this for dynamics in a Bloch band where point degeneracies carrying opposite winding numbers are generically offset in energy, allowing both an anomalous charge Hall conductance with the sign selected by off-resonance coupling to circularly polarized light and a related anomalous orbital Hall conductance activated by layer buckling.
关键词： Berry curvature,anomalous transport,circularly polarized light,triangular lattice,orbital Hall conductance
更新于2025-09-11 14:15:04
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[IEEE 2018 8th International Conference on Localization and GNSS (ICL-GNSS) - Guimaraes (2018.6.26-2018.6.28)] 2018 8th International Conference on Localization and GNSS (ICL-GNSS) - Direct position estimation from wavefront curvature with single antenna array
摘要： In this paper we investigate the possibility to perform direct positioning by retrieving information from the wavefront curvature. Despite such an approach has been considered in the past at microwave and acoustic frequencies using extremely large antennas, it is of interest to investigate its potential exploitation at mm-wave with practical size antennas in the context of next 5G systems. Thus, here we first consider a dedicated model to gather the source position information from the wavefront curvature for different array architectures, i.e., traditional and lens-based arrays, and successively we derive the maximum likelihood estimator to investigate the attainable performance. Results, obtained for different number of antennas, i.e., for different array apertures, confirm the possibility to achieve interesting positioning performance using a single antenna array with limited dimensions.
关键词： mm-wave,direct positioning,massive array,lens array,Wavefront curvature
更新于2025-09-11 14:15:04
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Handbook of Mechanics of Materials || Surface/Interface Stress and Thin Film Stress
摘要： Thin ?lm stress is critical for the reliability and electronic/optoelectronic properties of thin ?lm devices. In this chapter, we systematically discussed the effects of surface and interface stresses on the ?lm stress development during growth of polycrystalline ?lms at the initial and ?nal growth stage. We demonstrate that surface stress plays an important role at the initial stage of ?lm growth (island growth stage), and conventional stress analysis technology such as wafer curveture experiments may not be applicable at this stage. At the late stage of ?lm growth, we also show that adatom insertion into the grain boundaries is the primary mechanism of compressive stress development.
关键词： interface stress,Thin ?lm stress,adatom insertion,wafer curvature,grain boundaries,surface stress,polycrystalline ?lms
更新于2025-09-10 09:29:36
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Modified Curvature-based Trigonometric Identities for Retinal Blood Vessel Tortuosity Measurement in Diabetic Retinopathy Fundus Images
摘要： In current clinical practice, there is no specific standard and grading system that can be used to measure the behaviour of the retinal blood vessel curvature. The retinal blood vessel curvature is measured based on clinical experiences. It is very subjective and inconsistent to describe the presence of tortuosity in fundus images. Thus, this paper aims to measure the tortuosity of retinal blood vessel using curvature-based method and investigate its relationship with diabetic retinopathy (DR) disease. The proposed tortuosity measures have been tested on 43 fundus images belonging to patients who have been diagnosed with DR disease and validated by two clinical experts from our collaborative hospital. On average, the proposed algorithm achieved 90.7% (accuracy), 98.72% (sensitivity) and 9.3% (false negative rate), that shows significant tortuosity presence in diabetic retinopathy fundus images.
关键词： Tortuosity,Retinal Blood Vessel,Digital Fundus Images,Diabetic Retinopathy,Curvature-based Method
更新于2025-09-10 09:29:36
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Analysis of Factors that Influence on Accuracy of Intraocular Lens Power Calculation
摘要： To investigate which factors primarily influence refractory errors between various formulas used to calculate intraocular lens (IOL) power. Methods: Records of 266 eyes of 191 patients who underwent uneventful cataract surgery were reviewed retrospectively. IOL power was determined using SRK/T, HofferQ (H/Q), Master SRK/T (M/T), Master HofferQ (M/Q), Master Holladay (M/Hol), and Master Haigis (M/Hai). The mean absolute error (MAE) of each formula was compared; MAE was defined as the difference between the postoperative spherical equivalence (SE) determined 1 month after surgery and the predicted SE. Factors that could have influenced interformula refractive errors were analyzed. Patients were divided into 3 groups based on average keratometric value (Kavg) and the inter-group differences of the AE of each formula were analyzed. Effects of corneal curvature on changes in AE of each formula were evaluated by linear regression. Results: The MAE was minimized in the M/T formula, followed by the M/Hol, M/Hai, SRK/T, H/Q, and M/Q formulas. Interformula MAE differences were not statistically significant. Kavg and AXL were significantly influenced by the different predictive values between formulas in univariate analysis, but only AXL was significant in multivariate analysis. The AE in each formula among the 3 groups according to keratometry was significantly different in SRK, M/Hol, and M/Hai. Linear regression analysis showed a significant negative correlation between Kavg, AE of SRK/T and the MHai formula. In particular, this effect was more pronounced in those with short AXL (<22.5 mm). Conclusions: There were no significant MAE differences between formulas. AXL was a significant factor that influenced the differences between formulas. SRK/T and M/Hai may be affected by outside the normal range of corneal curvatures.
关键词： Corneal curvature,Refractive error,Intraocular lens power calculation,Axial length
更新于2025-09-09 09:28:46
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Person Recognition Using 3-D Palmprint Data Based on Full-Field Sinusoidal Fringe Projection
摘要： Palmprint-based biometrics has been widely studied for human recognition. However, for feature extraction and matching, most of the current systems use a 2-D image, which can be easily forged. As depth information is included, 3-D palmprints are more competitive in anticounterfeiting. This paper presents a novel person recognition method using 3-D palmprint data. The full-field sinusoidal fringe projection technique is employed to collect 3-D palmprint data remotely and quickly, from which the orientation feature of the mean curvature image is extracted through a revised Gabor filter. An effective feature matching strategy called the binary code list is proposed for classification. Using the developed capture system, a 3-D palmprint database is established, and verification and identification experiments are performed. The PolyU 3-D palmprint database is also used to evaluate the performance of the proposed recognition method. Compared with traditional single-mode feature-based 3-D palmprint recognition methods, the proposed method is more accurate, efficient, and faster.
关键词： person recognition,binary code list,3-D palmprint,Gabor filter,fringe projection,mean curvature image (MCI)
更新于2025-09-09 09:28:46
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15.1: <i>Invited Paper:</i> Bonding Spacer Technologies for Future Foldable LCDs using Ultra-Thin Polyimide Substrates
摘要： We have developed foldable LCD using ultra-thin polyimide substrates and bonding polymer spacer and successfully achieved small curvature of radius less than 2mm. We discuss the bonding spacer can suppress the deformation of plastic substrate and achieve high image quality in bending state.
关键词： Polyimide substrate,Small radius of curvature,Foldable LCD,Bending stress,Bonding spacer,Liquid crystal display
更新于2025-09-09 09:28:46