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Start Over Author "Du, Shanshan" Publisher elsevier bv
77 results on '"Du, Shanshan"'

29. Effect of substrate defects on LIDT of (BiTm)3(GaFe)5O12 films grown by LPE

Author

Ding Zhang, Wang Ming, Huaiwu Zhang, Yong Jiang, Qinghui Yang, Ihor I. Syvorotka, and Du Shanshan

Subjects
Materials science, business.industry, General Physics and Astronomy, Polishing, Gadolinium gallium garnet, 02 engineering and technology, Surfaces and Interfaces, General Chemistry, Substrate (electronics), 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Epitaxy, 01 natural sciences, Crystallographic defect, 0104 chemical sciences, Surfaces, Coatings and Films, Crystal, chemistry.chemical_compound, chemistry, Lapping, Optoelectronics, 0210 nano-technology, business, Layer (electronics)
Abstract

Recently, demands for magneto-optical (MO) materials with high laser-induced damage thresholds (LIDT) increased rapidly with the continuous development of high power lasers. In order to study the effect of substrate defects on LIDT of (BiTm)3(GaFe)5O12 films, in this study, (BiTm)3(GaFe)5O12 films without gadolinium gallium garnet (GGG) substrates and (BiTm)3(GaFe)5O12/GGG films were prepared by liquid-phase epitaxial (LPE) and mechanical lapping and polishing method. The optical and magneto-optical properties, crystal structure, LIDT and laser-induced damage morphologies of the prepared films were investigated. Experimental results pointed out that epitaxial (BiTm)3(GaFe)5O12 films have very high crystal and surface quality. A discontinuous defective layer with thickness of about 0–500 nm is located between GGG substrates and epitaxial films. Laser-induced damage tests and damage morphologies demonstrate that the discontinuous defective layers have an important effect on LIDT of epitaxial films, and LIDT of epitaxy films can be significantly improved by removing GGG substrates and discontinuous defective layers.

Published
2019
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30. Laser-induced damage of garnet films grown by LPE

Author

Wang Ming, Ding Zhang, Ihor I. Syvorotka, Du Shanshan, Yong Jiang, Qinghui Yang, and Zhang Huaiwu

Subjects
Materials science, Optical isolator, 02 engineering and technology, Crystal structure, 010402 general chemistry, Epitaxy, 01 natural sciences, law.invention, Inorganic Chemistry, Crystal, law, Transmittance, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Spectroscopy, business.industry, Organic Chemistry, 021001 nanoscience & nanotechnology, Laser, Microstructure, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, Optoelectronics, 0210 nano-technology, business, Single crystal
Abstract

Laser-induced damage of magneto-optical (MO) materials is a key factor that limits the application of optical isolators in high-power laser systems. In order to investigate parameters that affecting laser-induced damage thresholds (LIDT) of MO garnet films grown by liquid-phase epitaxial (LPE) method, YIG, (LuBi)3Fe5O12 and (BiTm)3(GaFe)5O12 single crystal films with small lattice mismatch were prepared in this study. The transmittance, optical absorption coefficient, crystal structures, surface quality and laser-induced damage thresholds (LIDT) of the prepared three kinds of MO films were investigated. Microstructure analysis shows that single crystal garnet films grown by LPE method have high surface and crystal quality. Laser-induced damage tests (@1064 nm, 11 ns) pointed out that LIDT of YIG, (LuBi)3Fe5O12 and (BiTm)3(GaFe)5O12 films are 6.41 ± 0.18 J/cm2, 6.32 ± 0.25 J/cm2 and 4.11 ± 0.27 J/cm2, respectively, and intrinsic optical absorption coefficient of single crystal garnet films plays a decisive role in their laser-induced damage.

Published
2019
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31. Effect of lattice mismatch on the laser-induced damage thresholds of (BiTm)3(GaFe)5O12 thin films

Author

Yong Jiang, Wang Ming, Hao Junxiang, Huaiwu Zhang, Du Shanshan, Ihor I. Syvorotka, Qinghui Yang, and Ding Zhang

Subjects
Materials science, Verdet constant, Optical isolator, business.industry, General Physics and Astronomy, 02 engineering and technology, Surfaces and Interfaces, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Epitaxy, Laser, 01 natural sciences, 0104 chemical sciences, Surfaces, Coatings and Films, law.invention, law, Optoelectronics, Irradiation, Growth rate, Thin film, 0210 nano-technology, business, Single crystal
Abstract

Laser-induced damage of magneto-optical (MO) materials in optical isolators remains the crucial factor that limits the application for high-power lasers. In order to explore the application potentiality of Tm3+ and Bi3+ ions-substituted YIG thin films using in high-power laser systems and find parameters that affecting laser-induced damage thresholds (LIDT) of this films. Here, (BiTm)3(GaFe)5O12 single crystal thin films with different growth rate were prepared through liquid-phase epitaxy method. The optical, magneto-optical, LIDT and surface morphologies before and after laser irradiation of the prepared thin films were investigated. Experimental results pointed out that the surface defects generated by lattice mismatch between films and substrates, residual melt in surface defects and difference in intrinsic optical absorption coefficient (α) were the key factors affecting LIDT of (BiTm)3(GaFe)5O12 thin films. Moreover, the maximum Verdet constant (−2.595 × 10−4°/(Oe μm)), the lowest α (66 cm−1@1064 nm) and the highest LIDT (4.28 J/cm2) were obtained of the film with growth rate of 0.84 μm/min, this indicates that the prepared (BiTm)3(GaFe)5O12 thin films are attractive candidate to substitute conventional bulk single crystal MO materials in high-power laser systems.

Published
2019
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39. Balanced single-shot object detection using cross-context attention-guided network

Author

Yuejie Zhang, Li Huayu, Lin Zheng, Rui Feng, Shuyu Miao, Du Shanshan, Weiguo Fan, and Liu Tianbi

Subjects
Computer science, Mechanism (biology), Detector, Single shot, Context (language use), computer.software_genre, Object detection, Artificial Intelligence, Signal Processing, Metric (mathematics), Benchmark (computing), Computer Vision and Pattern Recognition, Data mining, computer, Software, Communication channel
Abstract

In real-world application scenarios, object detection usually encounters two technical challenges, i.e., high accuracy and high speed. Although the latest detection frameworks based on anchor-free detection have achieved outstanding performance, they cannot be widely used in real-world scenarios due to their model complexity and slow speed. In this paper, inspired by cross-context attention mechanism of human visual systems, we propose a light but effective single-shot detection framework using Cross-context Attention-guided Network (CCAGNet) to balance the accuracy and speed. CCAGNet uses attention-guided mechanism to highlight the interaction of object-synergy regions, and suppresses non-object-synergy regions by combining Cross-context Attention Mechanism (CCAM), Receptive Field Attention Mechanism (RFAM), and Semantic Fusion Attention Mechanism (SFAM). The main contribution of our work includes establishing a novel attention mechanism that takes the context information of channel, spatial, cross- and adjacent-regions into consideration simultaneously. Extensive experiments demonstrate the feasibility and effectiveness of our method on the public benchmark datasets. To the best of our knowledge, CCAGNet obtains the state-of-the-art performance on both PascalVOC and MSCOCO with the excellent trade-off between accuracy and speed among single-shot detectors. Especially, the Average Precision (AP) metric is significantly improved by 17.0% on small object detection on MSCOCO.

Published
2022
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48. Periphery-aware COVID-19 diagnosis with contrastive representation enhancement

Author

Jilan Xu, Xiangyang Xue, Fei Shan, Yuejie Zhang, Junlin Hou, Longquan Jiang, Rui Feng, and Du Shanshan

Subjects
Coronavirus disease 2019 (COVID-19), Computer science, 02 engineering and technology, 01 natural sciences, Article, Periphery-aware Spatial Prediction (PSP), Community-acquired pneumonia, Discriminative model, Artificial Intelligence, 0103 physical sciences, Similarity (psychology), 0202 electrical engineering, electronic engineering, information engineering, medicine, Automated COVID-19 Diagnosis, 010306 general physics, business.industry, Representation (systemics), Chest CT Images, Pattern recognition, medicine.disease, Pneumonia, Contrastive Representation Enhancement (CRE), Viral pneumonia, Signal Processing, 020201 artificial intelligence & image processing, Computer Vision and Pattern Recognition, Artificial intelligence, Spatial prediction, business, Software
Abstract

Computer-aided diagnosis has been extensively investigated for more rapid and accurate screening during the outbreak of COVID-19 epidemic. However, the challenge remains to distinguish COVID-19 in the complex scenario of multi-type pneumonia classification and improve the overall diagnostic performance. In this paper, we propose a novel periphery-aware COVID-19 diagnosis approach with contrastive representation enhancement to identify COVID-19 from influenza-A (H1N1) viral pneumonia, community acquired pneumonia (CAP), and healthy subjects using chest CT images. Our key contributions include: 1) an unsupervised Periphery-aware Spatial Prediction (PSP) task which is designed to introduce important spatial patterns into deep networks; 2) an adaptive Contrastive Repre-sentation Enhancement (CRE) mechanism which can effectively capture the intra-class similarity and inter-class difference of various types of pneumonia. We integrate PSP and CRE to obtain the representations which are highly discriminative in COVID-19 screening. We evaluate our approach comprehensively on our constructed large-scale dataset and two public datasets. Extensive experiments on both volume-level and slice-level CT images demonstrate the effectiveness of our proposed approach with PSP and CRE for COVID-19 diagnosis.

Published
2021
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49. LPE growth of (NdGdBi)3Fe5O12 films with high FOM and high LIDTs at a wavelength of around 1 μm

Author

Wang Ming, Ihor I. Syvorotka, Qi-Ye Wen, Qinghui Yang, Ding Zhang, Du Shanshan, and Huaiwu Zhang

Subjects
Materials science, Dopant, business.industry, General Physics and Astronomy, 02 engineering and technology, Surfaces and Interfaces, General Chemistry, Crystal structure, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Epitaxy, Laser, 01 natural sciences, 0104 chemical sciences, Surfaces, Coatings and Films, law.invention, Wavelength, Lattice constant, law, Optoelectronics, Insertion loss, Figure of merit, 0210 nano-technology, business
Abstract

(NdGdBi)3Fe5O12 mono-crystalline films with high magneto-optical figure of merit (FOM) and high laser-induced damage thresholds (LIDTs) at a wavelength of around 1 μm have been grown in this study. Crystal structure, phase composition, magneto-optical (MO) properties and LIDTs of the grown (NdGdBi)3Fe5O12 films were discussed in detail. Tested results show that (NdGdBi)3Fe5O12 films exhibit a low insertion loss of 0.5 dB, a high FOM of 78.7 deg/dB and a high LIDTs of 9.12 J/cm2 at 1.06 μm wavelength. Lattice constant and dopants are two key factors to determine FOM and LIDTs of Bi-doped iron garnet films grown by liquid-phase epitaxial method. The excellent MO properties and LIDTs indicate that (NdGdBi)3Fe5O12 films grown in this study have a great potential to be used in 1–1.1 μm high-power lasers.

Published
2020
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