2023
2023
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Record 157 of
Title:Si Photonics FMCW LiDAR Chip with Solid-State Beam Steering by Interleaved Coaxial Optical Phased Array
Author(s):Lei, Yufang(1,2); Zhang, Lingxuan(1,2); Yu, Zhiyuan(1); Xue, Yulong(1,2); Ren, Yangming(1,2); Sun, Xiaochen(1,2)Source: Micromachines Volume: 14 Issue: 5 Article Number: 1001 DOI: 10.3390/mi14051001 Published: May 2023Abstract:LiDAR has attracted increasing attention because of its strong anti-interference ability and high resolution. Traditional LiDAR systems rely on discrete components and face the challenges of high cost, large volume, and complex construction. Photonic integration technology can solve these problems and achieve high integration, compact dimension, and low-cost on-chip LiDAR solutions. A solid-state frequency-modulated continuous-wave LiDAR based on a silicon photonic chip is proposed and demonstrated. Two sets of optical phased array antennas are integrated on an optical chip to form a transmitter–receiver interleaved coaxial all-solid-state coherent optical system which provides high power efficiency, in principle, compared with a coaxial optical system using a 2 × 2 beam splitter. The solid-state scanning on the chip is realized by optical phased array without a mechanical structure. A 32-channel transmitter–receiver interleaved coaxial all-solid-state FMCW LiDAR chip design is demonstrated. The measured beam width is 0.4° × 0.8°, and the grating lobe suppression ratio is 6 dB. Preliminary FMCW ranging of multiple targets scanned by OPA was performed. The photonic integrated chip is fabricated on a CMOS-compatible silicon photonics platform, providing a steady path to the commercialization of low-cost on-chip solid-state FMCW LiDAR. ? 2023 by the authors.Accession Number: 20232314177540 -
Record 158 of
Title:Suppressing grating lobes of large-aperture optical phased array with circular array design
Author(s):Lei, Yufang(1,2); Zhang, Lingxuan(1,2); Xue, Yulong(1,2); Ren, Yangming(1,2); Zhang, Qihao(1,2); Zhang, Wenfu(1,2); Sun, Xiaochen(1,2)Source: Applied Optics Volume: 62 Issue: 15 Article Number: null DOI: 10.1364/AO.488916 Published: May 20, 2023Abstract:An optical phased array (OPA), especially a two-dimensional (2D) OPA, suffers from the trade-off among steering range, beam width, and the number of antennas. Aperiodic 2D array designs currently aimed to reduce the number of antennas and reduce grating lobes within a wide range fall short when an aperture approaches millimeter size. A circular OPA design is proposed to address this issue. The circular design substantially reduces the number of antennas while achieving the same wide steering range and narrow beam width of optimized aperiodic 2D OPA designs. Its efficient suppression of grating lobes, the key to a wide steering range with minimal number of antennas and large antenna spacing, is theoretically studied and validated by simulation. The novel, to the best of our knowledge, design allows less than 100 antennas, orders of magnitude reduction, for millimeter size aperture OPA designs. It paves the way for commercialization by significantly reducing control complexity and power consumption. ? 2023 Optica Publishing Group.Accession Number: 20232514283002 -
Record 159 of
Title:PMD tolerant transmission using multiple optical phase conjugators in the discretely amplified systems
Author(s):Tong, Xiaogang(1); Cao, Weiwei(2); Zhang, Junsheng(1); Liang, Haijian(1)Source: Journal of Optical Communications Volume: null Issue: null Article Number: null DOI: 10.1515/joc-2023-0250 Published: 2023Abstract:In this paper, the impact of polarization mode dispersion (PMD) on system performance in coherent optical transmission assisted by optical phase conjugation (OPC) technique is numerically investigated for a 9-channel PM-4QAM system at 128Gbit/s. The OPC-aided transmission, amplified with lumped erbium doped fiber amplifier (EDFA), is a variation of the conventional dispersion-managed link, which is also called dispersion-inverted link. We demonstrate that introducing more OPCs along the link can partly suppress the PMD-induced impairments and thus improve the system performance significantly. Results of 960-km dispersion-managed transmission show that PMD effect will cause a performance penalty of 1.8 ? dB when using mid-link OPC (i.e., only 1-OPC), while this penalty will decrease to about 0.4 ? dB when employing 6-OPCs along the link. Comparing with conventional digital back-propagation (DBP) technique, a performance improvement of about 3.1 ? dB is observed with multi-OPCs when fiber PMD is equal to 0.1ps/ k m $\sqrt{km}$. ? 2023 Walter de Gruyter GmbH, Berlin/Boston 2023.Accession Number: 20234214909837 -
Record 160 of
Title:TransMVU: Multi-view 2D U-Nets with transformer for brain tumour segmentation
Author(s):Liu, Zengxin(1,2,3); Ma, Caiwen(1,2); She, Wenji(1,3); Wang, Xuan(1,3)Source: IET Image Processing Volume: 17 Issue: 6 Article Number: null DOI: 10.1049/ipr2.12762 Published: May 11, 2023Abstract:Medical image segmentation remains particularly challenging for complex and low-contrast anatomical structures, especially in brain MRI glioma segmentation. Gliomas appear with extensive heterogeneity in appearance and location on brain MR images, making robust tumour segmentation extremely challenging and leads to highly variable even in manual segmentation. U-Net has become the de facto standard in medical image segmentation tasks with great success. Previous researches have proposed various U-Net-based 2D Convolutional Neural Networks (2D-CNN) and their 3D variants, called 3D-CNN-based architectures, for capturing contextual information. However, U-Net often has limitations in explicitly modelling long-term dependencies due to the inherent locality of convolution operations. Inspired by the recent success of natural language processing transformers in long-range sequence learning, a multi-view 2D U-Nets with transformer (TransMVU) method is proposed, which combines the advantages of transformer and 2D U-Net. On the one hand, the transformer encodes the tokenized image patches in the CNN feature map into an input sequence for extracting global context for global feature modelling. On the other hand, multi-view 2D U-Nets can provide accurate segmentation with fewer parameters than 3D networks. Experimental results on the BraTS20 dataset demonstrate that our model outperforms state-of-the-art 2D models and classic 3D model. ? 2023 The Authors. IET Image Processing published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.Accession Number: 20230813614016 -
Record 161 of
Title:Monocular polarized three-dimensional absolute depth reconstruction technology for multi-target scenes
Author(s):Li, Xuan(1,2); Liu, Zhiqiang(1); Cai, Yudong(2); Yan, Jinke(1); Wu, Wenxin(1); Guo, Gao(3); Shao, Xiaopeng(1,2)Source: Applied Optics Volume: 62 Issue: 21 Article Number: null DOI: 10.1364/AO.490003 Published: July 2023Abstract:The traditional polarization three-dimensional (3D) imaging technology has limited applications in the field of vision because it can only obtain the relative depth information of the target. Based on the principle of polarization stereo vision, this study combines camera calibration with a monocular ranging model to achieve high-precision recovery of the target’s absolute depth information in multi-target scenes. Meanwhile, an adaptive camera intrinsic matrix prediction method is proposed to overcome changes in the camera intrinsic matrix caused by focusing on fuzzy targets outside the depth of field in multi-target scenes, thereby realizing monocular polarized 3D absolute depth reconstruction under dynamic focusing of targets at different depths. Experimental results indicate that the recovery error of monocular polarized 3D absolute depth information for the clear target is less than 10%, and the detail error is only 0.19 mm. Also, the precision of absolute depth reconstruction remains above 90% after dynamic focusing on the blurred target. The proposed monocular polarized 3D absolute depth reconstruction technology for multi-target scenes can broaden application scenarios of the polarization 3D imaging technology in the field of vision. ? 2023 Optica Publishing Group.Accession Number: 20233114461017 -
Record 162 of
Title:Attosecond pulses of light: Shining the way to the world of electrons in matter
Author(s):Wang, Hushan(1); Fu, Yuxi(1); Cheng, Ya(2)Source: Kexue Tongbao/Chinese Science Bulletin Volume: 68 Issue: 36 Article Number: null DOI: 10.1360/TB-2023-1113 Published: 2023Abstract:The Nobel Prize in Physics 2023 was awarded to Pierre Agostini (from The Ohio State University, Columbus, USA), Ferenc Krausz (from Max Planck Institute of Quantum Optics, Garching and Ludwig-Maximilians-Universit?t München, Germany) and Anne L’Huillier (from Lund University, Sweden), for their contributions to experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter. From the official website of the Nobel Prize, we can see the introduction "An attosecond (10–18 s) is so short that there are as many in one second as there have been seconds since the birth of the universe". The attosecond pulses of light have given humanity new tools for exploring the world of electrons in matter and enabled the investigation of ultrafast processes that were previously impossible to follow. Back to 1887, Hertz discovered that under the irradiation of electromagnetic waves with a high enough frequency, electrons inside the material will be excited to form an electric current, which is the famous photoelectric effect. However, the photoelectric effect contradicted the electromagnetic wave theory founded by Maxwell and could not be understood for a long time. In 1905, Einstein explained the photoelectric effect for the first time by proposing the hypothesis of photons, which also promoted the establishment of quantum mechanics. However, Einstein’s theory of the photoelectric effect only holds true under the conditions of perturbative interactions caused by weak light intensity. Then, strong field physics emerges, with the introduction of multiphoton ionization, tunneling ionization, and above-threshold ionization, paving the way for the birth of attosecond pulses of light. In 1987, Anne L’Huillier achieved high harmonic generation in experiments when she transmitted infrared laser light through a noble gas. In 1993, the 3-step model of high harmonic generation was proposed by Kulander and Paul Corkum. In 2001, Pierre Agostini succeeded in producing attosecond pulse trains, in which each pulse lasted just 250 attoseconds. In the same year, Ferenc Krausz experimentally realized the first isolated attosecond pulse that lasted 650 attoseconds. After a long journey, humanity finally realized attosecond pulses of light and obtained the key to the electronic world. Nowadays, with the joint efforts of domestic and foreign researchers, attosecond pulses of light have already achieved the shortest pulse widths of 53 and 43 as, the highest photon energy of 1600 eV, the highest pulse energy of 240 nJ in the extreme ultraviolet band and pulse energies up to 10 nJ in the soft X-ray band. The attosecond pulses of light have been applied to various electronic dynamics studies, promoting the explanation of deep scientific problems in physics, chemistry, materials, biology, and other disciplines. To make breakthroughs and unleash the huge application potential of attosecond light sources, it has become an important development trend to build attosecond large-scale scientific facilities worldwide, for example, the European Extreme Light Infrastructure-Attosecond Light Pulse Source, and Advanced Attosecond Laser Infrastructure in China. The Nobel Prize in Physics 2023 has greatly inspired researchers in the field of attosecond science and technology. However, it is just the beginning for attosecond pulses, indicating that this field will have a more profound and extensive impact on mankind’s journey of exploring nature and innovating technology in the future. ? 2023 Chinese Academy of Sciences. All rights reserved.Accession Number: 20240215371407 -
Record 163 of
Title:Design of Schlieren Imaging facility for space combustion science experiment system
Author(s):Guo, Huinan(1); Ma, Yingjun(1); Shi, Kui(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12558 Issue: null Article Number: 1255804 DOI: 10.1117/12.2645877 Published: 2023Abstract:Under the condition of normal gravity, it is difficult to perceive weak changes of microscopic matter caused by material combustion. To meet the requirement of long-Term microgravity environment, it is necessary to establish a combustion science experimental system in space station. For combustion experiment on orbit, a compact optical observation facility is designed in this paper. The facility bases on schlieren imaging, which is able to observe density distribution and flow-field change in combustion experiment. According to the characteristics of space condition, a highly reliable optical lens and mechanical structure are designed. The simulation experimental results show that our design is of high reliability, which is able to be used in complex condition of space combustion experiment. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20230713574413 -
Record 164 of
Title:Deep neural network: As the novel pipelines in multiple preprocessing for Raman spectroscopy
Author(s):Gao, Chi(1,2,3); Zhao, Peng(1,2,3); Fan, Qi(1,2); Jing, Haonan(1,2,3); Dang, Ruochen(1,2,3); Sun, Weifeng(1,2,3); Feng, Yutao(1); Hu, Bingliang(1,2); Wang, Quan(1,2)Source: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy Volume: 302 Issue: null Article Number: 123086 DOI: 10.1016/j.saa.2023.123086 Published: December 5, 2023Abstract:Raman spectroscopy is a kind of vibrational method that can rapidly and non-invasively gives chemical structural information with the Raman spectrometer. Despite its technical advantages, in practical application scenarios, Raman spectroscopy often suffers from interference, such as noises and baseline drifts, resulting in the inability to acquire high-quality Raman spectroscopy signals, which brings challenges to subsequent spectral analysis. The commonly applied spectral preprocessing methods, such as Savitzky–Golay smooth and wavelet transform, can only perform corresponding single-item processing and require manual intervention to carry out a series of tedious trial parameters. Especially, each scheme can only be used for a specific data set. In recent years, the development of deep neural networks has provided new solutions for intelligent preprocessing of spectral data. In this paper, we first creatively started from the basic mechanism of spectral signal generation and constructed a mathematical model of the Raman spectral signal. By counting the noise parameters of the real system, we generated a simulation dataset close to the output of the real system, which alleviated the dependence on data during deep learning training. Due to the powerful nonlinear fitting ability of the neural network, fully connected network model is constructed to complete the baseline estimation task simply and quickly. Then building the Unet model can effectively achieve spectral denoising, and combining it with baseline estimation can realize intelligent joint processing. Through the simulation dataset experiment, it is proved that compared with the classic method, the method proposed in this paper has obvious advantages, which can effectively improve the signal quality and further ensure the accuracy of the peak intensity. At the same time, when the proposed method is applied to the actual system, it also achieves excellent performance compared with the common method, which indirectly indicates the effectiveness of the Raman signal simulation model. The research presented in this paper offers a variety of efficient pipelines for the intelligent processing of Raman spectroscopy, which can adapt to the requirements of different tasks while providing a new idea for enhancing the quality of Raman spectroscopy signals. ? 2023 Elsevier B.V.Accession Number: 20233014427895 -
Record 165 of
Title:Joint Texture Search and Histogram Redistribution for Hyperspectral Image Quality Improvement
Author(s):Hu, Bingliang(1); Chen, Junyu(1,2); Wang, Yihao(1); Li, Haiwei(1); Zhang, Geng(1)Source: Sensors Volume: 23 Issue: 5 Article Number: 2731 DOI: 10.3390/s23052731 Published: March 2023Abstract:Due to optical noise, electrical noise, and compression error, data hyperspectral remote sensing equipment is inevitably contaminated by various noises, which seriously affect the applications of hyperspectral data. Therefore, it is of great significance to enhance hyperspectral imaging data quality. To guarantee the spectral accuracy during data processing, band-wise algorithms are not suitable for hyperspectral data. This paper proposes a quality enhancement algorithm based on texture search and histogram redistribution combined with denoising and contrast enhancement. Firstly, a texture-based search algorithm is proposed to improve the accuracy of denoising by improving the sparsity of 4D block matching clustering. Then, histogram redistribution and Poisson fusion are used to enhance spatial contrast while preserving spectral information. Synthesized noising data from public hyperspectral datasets are used to quantitatively evaluate the proposed algorithm, and multiple criteria are used to analyze the experimental results. At the same time, classification tasks were used to verify the quality of the enhanced data. The results show that the proposed algorithm is satisfactory for hyperspectral data quality improvement. ? 2023 by the authors.Accession Number: 20231113711657 -
Record 166 of
Title:Numerical analysis of surface acoustic wave driven carriers transport in GaAs/AlGaAs quantum well
Author(s):Pang, Ziliang(1,2,3); Cao, Weiwei(1,2); Zheng, Jinkun(1,2); Bai, YongLin(1,2)Source: Journal of Nanophotonics Volume: 17 Issue: 3 Article Number: 036010 DOI: 10.1117/1.JNP.17.036010 Published: July 1, 2023Abstract:Surface acoustic waves (SAWs) with a strong enough piezoelectric field can capture and transport electrons and holes. The presence of SAWs and their photo-generated carriers' transport properties in the GaAs/AlGaAs quantum well (QW) is a potential scheme to achieve single photon sources and single photon detectors. We numerically solve the system of coupled Schr?dinger and Poisson equations and the carriers' radiative lifetime. A finite difference method of two-dimensional was developed as a conventional approach to the theoretical understanding of the presence in the QW through Python programs. The features of carriers' radiative lifetime are discussed as functions of the SAW wavelengths and SAW amplitudes. The spatial separation and radiative lifetime extension of the electrons and holes in the SAW-driven QW was explained by the method. ? 2023 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20234114853260 -
Record 167 of
Title:Four-beam sparse phase retrieval algorithm for sheared-beam imaging
Author(s):Chen, Minglai(1,2,3); Ma, Caiwen(1,2,3); Zhang, Yu(1,3); Liu, Hui(1,2,3); Luo, Xiujuan(1,2,3); Yue, Zelin(1,2); Zhao, Jing(1,2); Sun, Ce(1,3)Source: Optical Engineering Volume: 62 Issue: 7 Article Number: 073102 DOI: 10.1117/1.OE.62.7.073102 Published: July 1, 2023Abstract:Sheared-beam imaging (SBI) is an effective way of imaging through turbulent medium, such as atmosphere or scattering liquid. Traditionally, the imaging is based on the laser transmitter array consisting of three beams or five beams for coherent illumination to the remote object. Compared with the existing SBI methods, the four-beam sparse sampling imaging method has been proposed, which may have more advantages; it not only sparses the detector elements but also reduces the number of emitted beams. However, the traditional phase retrieval algorithms are not suitable for the four-beam sparse sampling imaging. We propose a four-beam sparse phase retrieval (F-BSPR) algorithm, which uses the phase differences from both horizontal and vertical components and the phase differences from other components when the phase is retrieving. The proposed phase retrieval algorithm can better connect the phase difference and improve the accuracy of the phase retrieval. Furthermore, the imaging quality is improved. Simulation and experimental results show that the proposed algorithm is effective and feasible when the number of detector elements is sparse by 50%. Compared to the traditional four-beam phase retrieval method, the proposed F-BSPR method has better imaging quality and robustness. ? 2023 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20233414581768 -
Record 168 of
Title:Review of Reconstruction Methods for Spectral Snapshot Compressive Imaging
Author(s):Yuan, Hao(1); Ding, Xiaoming(1,2); Yan, Qiangqiang(2); Wang, Xiaocheng(1); Li, Yupeng(1); Han, Tingting(1)Source: Lecture Notes in Electrical Engineering Volume: 872 LNEE Issue: null Article Number: null DOI: 10.1007/978-981-99-2653-4_39 Published: 2023Abstract:Snapshot compressive imaging (SCI) uses a 2D sensor to obtain higher dimensional data and then reconstructs the underlying high-dimension data by elaborate algorithms. Applying SCI to capture hyperspectral images is known as spectral SCI. Although this technique has been proposed for more than a decade, it has not been widely used, mainly because its reconstruction accuracy and reconstruction speed are not yet satisfactory, which is the research focus on spectral SCI. This paper investigates the literatures on reconstruction methods of spectral SCI, mainly involving coded aperture optimization, model-based reconstruction algorithms and deep learning-based reconstruction algorithms. In this paper, we also provide a summary of studies on noise modeling and denoising for reconstructed spectral SCI data. ? 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Accession Number: 20232314201509