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Evaluation of occlusion immunities of free-space orbital angular momentum shift keying

Optics Express 2025年第6期33卷 13494-13505页

作者： Yang, Jinyu Zhang, Shurui Li, Lang Gao, Mingwei Gao, Chunqing Fu, Shiyao School of Optics and Photonics Beijing Institute of Technology Beijing100081 China Key Laboratory of Information Photonics Technology Ministry of Industry and Information Technology of the People’s Republic of China Beijing100081 China Key Laboratory of Photoelectronic Imaging Technology and System Ministry of Education of the People’s Republic of China Beijing100081 China National Key Laboratory on Near-Surface Detection Beijing100072 China

Orbital angular momentum (OAM) provides a new high-dimensional degree-of-freedom for lasers enabling high-dimensional shift keying, thus showing huge potential in free-space optical data-transmissions. Ensuring the accuracy of data transmission is of concern in any communication system. However, in the free-space OAM shift keying link, interferences from environmental occlusions will broaden the OAM spectrum and thus affect the correctness of information received. In this paper, the occlusion immunities of two commonly used OAM shift keying strategies—OAM-encoding-symbols and OAM-encoding-bits—are evaluated under different occlusion scenarios. We introduce radial, azimuthal, and random occlusions into the link and then analyze the bit error rate (BER) of various OAM shift keying strategies. The results illustrate that the strategy of OAM-encoding-symbols exhibits stronger occlusion immunity with zero BER than OAM-encoding-bits. Moreover, proof-of-concept experiments are done to transmit grayscale images under occlusions. The final decoding results show identical data-transmission performance with simulations. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Bit error rate

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Selective formation of generalized optical skyrmions

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Optics Letters 2025年第9期50卷 2840-2843页

作者： Zhang, Haojun Gao, Chunqing Fu, Shiyao School of Optics and Photonics Beijing Institute of Technology Beijing100081 China Key Laboratory of Information Photonics Technology Ministry of Industry and Information Technology of the People’s Republic of China Beijing100081 China Key Laboratory of Photoelectronic Imaging Technology and System Ministry of Education of the People’s Republic of China Beijing100081 China National Key Laboratory on Near-Surface Detection Beijing100072 China

Optical skyrmions, a type of topologically protected quasiparticle, have undergone various deformations in recent years. In this Letter, we present a scheme that can achieve the selective formation of generalized optical skyrmions. In our proposal, a liquid-crystal spatial light modulator and a variable liquid-crystal retarder, both of which are commonly programmable devices, are employed, allowing for the on-demand precise manipulation of topological textures of various quasiparticles including but not limited to skyrmions, antiskyrmions, and bimerons. The proof-of-concept experiments illustrate that generalized optical skyrmions whose skyrmion number up to 5 can be well generated with on-demand tailored topological textures. While maintaining a simple setup, the system demonstrates a notable capacity for the manipulation of intricate high-order textures, signifying its considerable potential for extensive and sophisticated applications in the generation and manipulation of skyrmions. © 2025 Optica Publishing Group.

关键词： Topology

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Temporal multiplexing coding strategy for spatiotemporal compressed imaging 4

Temporal multiplexing coding strategy for spatiotemporal com...

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4th International Computational imaging Conference, CITA 2024

作者： Hao, Xiaowen Ke, Jun School of Optics and Photonics Beijing Institute of Technology Beijing100081 China Key Laboratory of Photo-electronic Imaging Technology and System Ministry of Education of China Beijing100081 China National Key Laboratory on Near-surface Detection Beijing100072 China

ISBN: (纸本)9781510688834

Spatiotemporal compressed imaging(STCI) aims to improve the spatial and temporal resolution of an imaging system simultaneously, which can effectively alleviate the mutual constraints between the two imaging resolutions. However, the development of STCI is limited by the effectively modulate target scenes in dual-domain, and by the back-end reconstruction process which doesn't work well for high compression ratio(CR). In this paper, we propose a temporal multiplexing coding strategy for STCI, which can effectively help the reconstruction algorithm for a large CR. Simulated experiments are implemented to demonstrate our idea. The proposed method can achieve nice spatiotemporal reconstructions with CR equal to 128:1, in which the spatial CR is 16:1 and the temporal CR is 8:1. © 2025 SPIE.

关键词： Image coding

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Optimizing object classification with single-pixel imaging and transformer networks 4

Optimizing object classification with single-pixel imaging a...

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4th International Computational imaging Conference, CITA 2024

作者： Cheng, Yin Liao, Yusen Sun, Xin Ke, Jun School of Optics and Photonics Beijing Institute of Technology Beijing100081 China Key Laboratory of Photo-electronic Imaging Technology and System Ministry of Education of China Beijing100081 China National Key Laboratory on Near-surface Detection Beijing100072 China

ISBN: (纸本)9781510688834

Traditional computer vision tasks rely on high-quality images for classification, but single-pixel imaging (SPI) uses compressive sensing with a bucket detector to simplify hardware and reduce costs. However, factors like atmospheric turbulence can degrade SPI image quality, lowering classification accuracy. To address this, a block-based single-pixel image-free transformer classification framework is proposed. It uses a learnable binary sampling matrix for flexible sampling during SPI and divides the measurements into blocks, which are processed by a transformer network. Each block is treated as a sequence element, allowing the transformer to capture spatial and contextual relationships. Experiments show strong robustness to atmospheric turbulence, achieving 87% classification accuracy even at a 1% sampling rate, making this method suitable for challenging environments. © 2025 SPIE.

关键词： Pixels

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Skin tissue classification based on Mueller matrix polarization imaging and machine learning

Skin tissue classification based on Mueller matrix polarizat...

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Polarized Light and Optical Angular Momentum for Biomedical Diagnostics 2025

作者： Huang, Rui Deng, Kaisha He, Honghui Ma, Hui Guangdong Research Center of Polarization Imaging and Measurement Engineering Technology Shenzhen Key Laboratory for Minimal Invasive Medical Technologies Institute of Biopharmaceutical and Health Engineering Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen518055 China

ISBN: (纸本)9781510683921

As an emerging tool for characterizing tissue structures label-freely, Mueller matrix polarimetry shows a good application potential in clinical diagnosis. Especially, it is feasible to use Mueller matrix images to evaluate skin tissues, which represent structural similarity in different individuals and have abundant anisotropic fibrous structures. However, due to the complexity of layered skin tissue structures, an accurate classification method based on Mueller matrix polarimetry is needed. In this study, we propose an automatic skin tissue structure classification model based on machine learning-assisted Mueller matrix polarization imaging. First, we adopt statistical methods such as kernel density estimation and independent sample K-W test to explore the relationship between different skin structures and Mueller matrix parameters. We select parameters that could better represent the differences in skin tissue layers. Then, we use selection algorithms to filter out a series of features with high weights. Furthermore, we establish a classification model for mouse tail skin tissue, and various indicators are used to evaluate the classification effect of different feature combinations of Mueller matrix parameters under different algorithms. It is concluded that the data set obtained from the m42 images after screening by the mutual information method has the best performance on the multi-layer perceptron model. The results provide an accurate skin tissue classification model for identifying lesion areas and types based on machine learning-assisted Mueller matrix polarimetry. © 2025 SPIE

关键词： Polarimeters

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Systematic fusion of polarization indices for improved characterization of complex anisotropic media

Systematic fusion of polarization indices for improved chara...

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Polarized Light and Optical Angular Momentum for Biomedical Diagnostics 2025

作者： Tang, Qiaoqi Hao, Rui He, Honghui Ma, Hui Guangdong Research Center of Polarization Imaging and Measurement Engineering Technology Shenzhen Key Laboratory for Minimal Invasive Medical Technologies Institute of Biopharmaceutical and Health Engineering Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen518055 China

ISBN: (纸本)9781510683921

As a non-invasive, label-free technique with excellent sensitivity to microstructural features in biological tissues, polarization imaging shows great potential in biomedical studies and clinical applications recently. Especially, quantitative characterization and evaluation of birefringence property using Mueller matrix polarimetry can help us obtain useful information on fibrous structures in tissue samples, which are related to many physiological and pathological processes. In this study, we propose systematic fusion of polarization indices for improved characterization of birefringence dynamics in complex anisotropic media. We firstly obtain the polarization basis parameters from Mueller matrix and transformed them into fused polarization feature parameters by employing explicit analytic expressions. The approach combined multidimensional polarimetric information to improve the characterization ability for birefringence dynamic variation process in complex anisotropic media. Then we adopt the Monte Carlo simulation and backscattering Mueller matrix measurements to verify the ability of fused polarization feature parameters. The results demonstrate that the fused polarization feature parameters can be used to capture variations in both direction and magnitude of birefringence in complex anisotropic media with good adaptability and interpretability. These findings on one hand give a more general view of anisotropic structure changes in tissue samples, on the other hand offer new methodological insights of information extraction for computational polarimetry in biomedical research and clinical applications. © 2025 SPIE

关键词： Anisotropic media

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Infrared small target detection based on spatial attention density peaks searching

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Optoelectronics Letters 2025年第2期21卷 90-96页

作者： RAO Junmin LU Siyu LIU Shijian LI Fanming CAS Key Laboratory of Infrared System Detection and Imaging Technology Shanghai Institute of Technical PhysicsShanghai 200083China University of Chinese Academy of Sciences Beijing 100049China Shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai 200083China School of Information Science and Technology ShanghaiTech UniversityShanghai 201210China

The detection of small targets poses a significant challenge for infrared search and tracking (IRST) systems,as they must strike a delicate balance between accuracy and *** this paper,we propose a detection algorithm based on spatial attention density peaks searching (SADPS) and an adaptive window selection ***,the difference-of-Gaussians (DoG) filter is introduced for preprocessing raw infrared ***,the image is processed by ***,an adaptive window selection scheme is applied to obtain window templates for the target scale ***,the small target feature is used to enhance the target and suppress the ***,the true targets are segmented through a *** experimental results show that compared with the seven state-of-the-art small targets detection baseline algorithms,the proposed method not only has better detection accuracy,but also has reasonable time consumption.

关键词： template searching Infrared

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Correction strategy of azimuthal bias in Mueller matrix polarimetry for multilayer birefringent media

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Optics Express 2025年第9期33卷 19582-19593页

作者： Zheng, Haohan Zeng, Nan Ma, Hui He, Chao He, Honghui Guangdong Research Center of Polarization Imaging and Measurement Engineering Technology Shenzhen Key Laboratory for Minimal Invasive Medical Technologies Institute of Biopharmaceutical and Health Engineering Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen518055 China Department of Engineering Science University of Oxford Parks Road OxfordOX1 3PJ United Kingdom

Mueller matrix polarimetry is widely harnessed in biomedical studies and clinical applications as a powerful tool, enabling comprehensive and quantitative characterization of the optical and structural properties of tissue and cell specimens. However, for complex tissue specimens containing multilayer birefringent microstructures, we find a bias existing between all Mueller matrix-derived linear birefringence azimuth parameters and ground truth, placing critical decision-making at risk in biomedicine using polarimetry. In this paper, we dive deep into the underlying rationale of azimuthal bias in multilayer birefringent structures, proposing a sandwiched configuration hypothesis to offer a rigorous theoretical explanation for the azimuthal bias. Based on the theoretical analysis, we propose a correction strategy, which introduces a correction factor to debias the Mueller matrix-derived linear retardance azimuth parameters. Substantial experimental results on both monolayer and multilayer phantoms demonstrate the plausibility of the sandwiched configuration assumption and the effectiveness of the proposed correction method in alleviating azimuthal bias. The corrected azimuthal parameters enable quantitative and precise determination of linear birefringent orientation in complex layered media, facilitating the biomedical application of Mueller matrix polarimetry, such as in histopathology. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Birefringence

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Infrared aircraft few-shot classification method based on cross-correlation network

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红外与毫米波学报 2025年第1期44卷 103-111页

作者： HUANG Zhen ZHANG Yong GONG Jin-Fu Key Laboratory of Infrared System Detection and Imaging Technology Chinese Academy of SciencesShanghai 200083China University of Chinese Academy of Sciences Beijing 100049China Shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai 200083China

In response to the scarcity of infrared aircraft samples and the tendency of traditional deep learning to overfit,a few-shot infrared aircraft classification method based on cross-correlation networks is *** method combines two core modules:a simple parameter-free self-attention and *** analyzing the self-correlation and cross-correlation between support images and query images,it achieves effective classification of infrared aircraft under few-shot *** proposed cross-correlation network integrates these two modules and is trained in an end-to-end *** simple parameter-free self-attention is responsible for extracting the internal structure of the image while the cross-attention can calculate the cross-correlation between images further extracting and fusing the features between *** with existing few-shot infrared target classification models,this model focuses on the geometric structure and thermal texture information of infrared images by modeling the semantic relevance between the features of the support set and query set,thus better attending to the target *** results show that this method outperforms existing infrared aircraft classification methods in various classification tasks,with the highest classification accuracy improvement exceeding 3%.In addition,ablation experiments and comparative experiments also prove the effectiveness of the method.

关键词： infrared imaging aircraft classification few-shot learning parameter-free attention cross attention

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Intelligent tailoring of a broadband orbital angular momentum comb towards efficient optical convolution

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Photonics Research 2025年第5期13卷 1148-1157页

作者： Zhou, Shiyun Li, Lang Wang, Yishu Gao, Liliang Zhang, Zhichao Gao, Chunqing Fu, Shiyao School of Optics and Photonics Beijing Institute of Technology Beijing100081 China Key Laboratory of Photoelectronic Imaging Technology and System Ministry of Education Beijing100081 China Key Laboratory of Information Photonics Technology Ministry of Industry and Information Technology Beijing100081 China National Key Laboratory on Near-surface Detection Beijing100072 China

Due to the high-dimensional characteristics of photon orbital angular momentum (OAM), a beam can carry multiple OAMs simultaneously thus forming an OAM comb, which has been proved to show significant potential in both classical and quantum photonics. Tailoring broadband OAM combs on demand in a fast and accurate manner is a crucial basis for their application in advanced scenarios. However, obtaining phase-only gratings for the generation of arbitrary desired OAM combs still poses challenges. In this paper, we propose a multi-scale fusion learning U-shaped neural network that encodes a phase-only hologram for tailoring broadband OAM combs on-demand. Proof-of-principle experiments demonstrate that our scheme achieves fast computational speed, high modulation precision, and high manipulation dimensionality, with a mode range of −75 to +75, an average root mean square error of 0.0037, and a fidelity of 85.01%, all achieved in about 30 ms. Furthermore, we utilize the tailored broadband OAM combs in conducting optical convolution calculation, enabling vector convolution for arbitrary discrete functions, showcasing the extended capability of our proposal. This work opens, to our knowledge, new insight for on-demand tailoring of broadband OAM combs, paving the way for further advancements in high-dimensional OAM-based applications. © 2025 Chinese Laser Press.

关键词： Angular momentum

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