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Your search keyword '"Zheng, Yaoxian"' showing total 24 results
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24 results on '"Zheng, Yaoxian"'

1. Higher-order topological states in photonic Thue-Morse quasicrystals: quadrupole insulator and a new origin of corner states

Author

Xiong, Langlang, Zhang, Yu, Liu, Yufu, Zheng, Yaoxian, and Jiang, Xunya

Subjects
Physics - Optics, Condensed Matter - Other Condensed Matter
Abstract

Corner states (CSs) in higher-order topological insulators (HOTIs) have recently been of great interest in both crystals and quasicrystals. In contrast to electronic systems, HOTIs have not been found in photonic quasicrystals (PQCs). Here, we systemically study the higher-order topology in the two-dimensional Thue-Morse photonic quasicrystals (TM-PQCs). Not only the topological phase transition and the non-trivial CSs with fractional charge induced by multipole moments, but also a new type of CSs are found due to the complex structure of TM-PQCs near corners. The different origins of these CSs are also analyzed based on the tight-binding model. Our work opens the door to explore richer HOT physics beyond photonic crystals and the robustness of CSs in PQC shows the potential for applications.

Published
2022

3. Topological properties of two-dimensional photonic square lattice without $C_4$ and $M_{x(y)}$ symmetries

Author

Xiong, Langlang, Liu, Yufu, Zhang, Yu, Zheng, Yaoxian, and Jiang, Xunya

Subjects
Physics - Optics, Condensed Matter - Other Condensed Matter
Abstract

Rich topological phenomena, edge states and two types of corner states, are unveiled in a two-dimensional square-lattice dielectric photonic crystal without both $C_4$ and $M_{x(y)}$ symmetries. Specifically, non-trivial type-I corner states, which do not exist in systems with $C_4$ and $M_{x(y)}$ since the degeneracy, are protected by non-zero quadrupole moment, no longer quantized to but less than $0.5$. Excellent properties, e.g. sub-wavelength localization and air-concentrated field distribution, are presented. Type-II corner states, induced by long-range interactions, are easier realized due to asymmetry. This work broadens the topological physics for the symmetries-broken systems and provides potential applications.

Published
2022
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5. All-Optical Switching Using Cavity Modes in Photonic Crystals Embedded with Hyperbolic Metamaterials.

Author

Liu, Chang, Wei, Dong, Lin, Xiaochun, and Zheng, Yaoxian

Subjects
OPTICAL switching, LIGHT transmission, OPTICAL devices, LIGHT propagation, HYBRID systems, OPTICAL switches
Abstract

Hyperbolic metamaterials (HMMs) are highly anisotropic materials with the unique property of generating electromagnetic modes. Understanding how these materials can be applied to control the propagation of light waves remains a major focus in photonics. In this study, we inserted a finite-size HMM rod into the point defect of two-dimensional photonic crystals (PhCs) and investigated the unique cavity modes of this hybrid system. The HMM enhances the efficiency of the cavity system in controlling light transmission. Numerical results demonstrate that the cavity modes based on HMMs can be categorized into various types, showing high Q-factors and promising potential for resonant modulation. Furthermore, the switching performance of the cavity with an HMM rod was examined, revealing that the finite-size HMM modes are highly frequency-sensitive and suitable for nonlinear controlled all-optical switching. These switches, characterized by low power consumption and high extinction ratios, are highly suitable for integration into photonic systems. Our investigation on the new type of HMM cavity illustrates that anisotropic materials can be effectively applied in cavity systems to generate highly efficient modes for filtering and switching. [ABSTRACT FROM AUTHOR]

Published
2024
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18. A bottom-up summarization algorithm for videos in the wild

Author

Zheng Yaoxian, Xingming Qu, Zhenjun Han, Gang Pan, Di Sun, and Rufei Zhang

Subjects
Similarity (geometry), Computer science, Video summarization, lcsh:Electronics, Rank (computer programming), ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, lcsh:TK7800-8360, 020206 networking & telecommunications, 02 engineering and technology, Automatic summarization, lcsh:Telecommunication, lcsh:TK5101-6720, Clip growing, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, Bottom-up, Cluster analysis, Representation (mathematics), Algorithm, Energy (signal processing)
Abstract

Video summarization aims to provide a compact video representation while preserving the essential activities of the original video. Most existing video summarization approaches relay on identifying important frames and optimizing target energy by a global optimum solution. But global optimum may fail to express continuous action or realistically validate how human beings perceive a story. In this paper, we present a bottom-up approach named clip growing for video summarization, which allows users to customize the quality of the video summaries. The proposed approach firstly uses clustering to oversegment video frames into video clips based on their similarity and proximity. Simultaneously, the importance of frames and clips is evaluated from their corresponding dissimilarity and representativeness. Then, video clips and frames are gradually selected according to their energy rank, until reaching the target length. Experimental results on SumMe dataset show that our algorithm can produce promising results compared to existing algorithms. Several video summarizations results are presented in supplementary material.

Published
2019
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