2024

• Record 265 of
  
  Title:Duplex-Hierarchy Representation Learning for Remote Sensing Image Classification
  
  Author(s):Yuan, Xiaobin(1,2); Zhu, Jingping(1); Lei, Hao(3,4); Peng, Shengjun(5); Wang, Weidong(6); Li, Xiaobin(7)
  Source: Sensors  Volume: 24  Issue: 4  DOI: 10.3390/s24041130  Published: February 2024  
  Abstract:Remote sensing image classification (RSIC) is designed to assign specific semantic labels to aerial images, which is significant and fundamental in many applications. In recent years, substantial work has been conducted on RSIC with the help of deep learning models. Even though these models have greatly enhanced the performance of RSIC, the issues of diversity in the same class and similarity between different classes in remote sensing images remain huge challenges for RSIC. To solve these problems, a duplex-hierarchy representation learning (DHRL) method is proposed. The proposed DHRL method aims to explore duplex-hierarchy spaces, including a common space and a label space, to learn discriminative representations for RSIC. The proposed DHRL method consists of three main steps: First, paired images are fed to a pretrained ResNet network for extracting the corresponding features. Second, the extracted features are further explored and mapped into a common space for reducing the intra-class scatter and enlarging the inter-class separation. Third, the obtained representations are used to predict the categories of the input images, and the discrimination loss in the label space is minimized to further promote the learning of discriminative representations. Meanwhile, a confusion score is computed and added to the classification loss for guiding the discriminative representation learning via backpropagation. The comprehensive experimental results show that the proposed method is superior to the existing state-of-the-art methods on two challenging remote sensing image scene datasets, demonstrating that the proposed method is significantly effective. © 2024 by the authors.
  Accession Number: 20240815619383
• Record 266 of
  
  Title:Multi-Dimensional Fusion of Spectral and Polarimetric Images Followed by Pseudo-Color Algorithm Integration and Mapping in HSI Space
  
  Author(s):Guo, Fengqi(1,2); Zhu, Jingping(1); Huang, Liqing(2); Li, Feng(1); Zhang, Ning(3); Deng, Jinxin(1); Li, Haoxiang(1); Zhang, Xiangzhe(1); Zhao, Yuanchen(1); Jiang, Huilin(4); Hou, Xun(1)
  Source: Remote Sensing  Volume: 16  Issue: 7  DOI: 10.3390/rs16071119  Published: April 2024  
  Abstract:Spectral–polarization imaging technology plays a crucial role in remote sensing detection, enhancing target identification and tracking capabilities by capturing both spectral and polarization information reflected from object surfaces. However, the acquisition of multi-dimensional data often leads to extensive datasets that necessitate comprehensive analysis, thereby impeding the convenience and efficiency of remote sensing detection. To address this challenge, we propose a fusion algorithm based on spectral–polarization characteristics, incorporating principal component analysis (PCA) and energy weighting. This algorithm effectively consolidates multi-dimensional features within the scene into a single image, enhancing object details and enriching edge features. The robustness and universality of our proposed algorithm are demonstrated through experimentally obtained datasets and verified with publicly available datasets. Additionally, to meet the requirements of remote sensing tracking, we meticulously designed a pseudo-color mapping scheme consistent with human vision. This scheme maps polarization degree to color saturation, polarization angle to hue, and the fused image to intensity, resulting in a visual display aligned with human visual perception. We also discuss the application of this technique in processing data generated by the Channel-modulated static birefringent Fourier transform imaging spectropolarimeter (CSBFTIS). Experimental results demonstrate a significant enhancement in the information entropy and average gradient of the fused image compared to the optimal image before fusion, achieving maximum increases of 88% and 94%, respectively. This provides a solid foundation for target recognition and tracking in airborne remote sensing detection. © 2024 by the authors.
  Accession Number: 20241615921118
• Record 267 of
  
  Title:Monolithic PMN-39PT nanograting-assisted second harmonic generation enhancement
  
  Author(s):Li, Tianlun(1); Liu, Xin(2); Lu, Yang(3); Gao, Duorui(4); Zhang, Kai(3); Gan, Xuetao(1); Wei, Xiaoyong(2); Xu, Zhuo(2); Zhang, Lei(2)
  Source: Optics Express  Volume: 32  Issue: 6  DOI: 10.1364/OE.510869  Published: March 11, 2024  
  Abstract:Second harmonic generation plays a vital role in frequency conversion which mutually promotes the laser technology and allows the wavebands extension of new coherent source. The monolithic crystals are supposed to be a superior choice for harmonic generation due to long interaction distance, however, the phase-mismatch brought a sharp reduction in the conversion efficiency. Although birefringent phase-matching and quasi-phase-matching techniques are commonly utilized to fill the phase gap in monolithic crystals, these techniques are limited by the natural refractive index of crystal and the domain engineering, respectively. In recent years, subwavelength structures evolve as a flexible scheme to realize phase matching by engineering the geometry features of crystals. Here, structured nanogratings are designed and fabricated on a monolithic PMN-39PT (Pb(Mg1/3Nb2/3)O3-0.39PbTiO3) substrate, a novel ferroelectric crystal with promising optical prospect, for enhancing second harmonic generation, where birefringent or quasi phase-matching is hard to achieve. The nanograting-assisted second harmonic generation enhancement is observed which is not limited by the availability of thin crystalline films. Meanwhile, a boost in the second harmonic signal synchronously promotes the cascading third harmonic generation. This method may provide an alternative solution for enhanced harmonic generation on monolithic substrates and develop potential nonlinear optical materials for frequency conversion. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20241215768412
• Record 268 of
  
  Title:Ultralow-Noise K-Band Soliton Microwave Oscillator Using Optical Frequency Division
  
  Author(s):Niu, Rui(1,2,3); Hua, Tian-Peng(2,4); Shen, Zhen(1,2,3); Wang, Yu(1,2,3); Wan, Shuai(1,2,3); Sun, Yu Robert(2,4); Wang, Weiqiang(5,6); Zhao, Wei(5,6); Guo, Guang-Can(1,2,3); Zhang, Wenfu(5,6); Liu, Wen(7); Hu, Shui-Ming(2,3,4); Dong, Chun-Hua(1,2,3)
  Source: ACS Photonics  Volume: 11  Issue: 4  DOI: 10.1021/acsphotonics.3c01247  Published: April 17, 2024  
  Abstract:Compact, low-noise microwave oscillators are required throughout a wide range of applications such as radar systems, wireless networks, and frequency metrology. Optical frequency division via an optical frequency comb provides a powerful tool for low-noise microwave signal generation. Here, we experimentally demonstrate an optical reference down to 26 GHz frequency division based on the dissipative Kerr soliton comb, which is generated on a CMOS-compatible, high-index doped silica glass platform. The optical reference is generated through two continuous wave lasers locked to an ultralow expansion cavity. The dissipative Kerr soliton comb with a repetition rate of 26 GHz acts as a frequency divider to derive an ultralow-noise microwave oscillator, with a phase noise level of −101.3 dBc/Hz at a 100 Hz offset frequency and −132.4 dBc/Hz at a 10 kHz offset frequency. Furthermore, the Allan deviation of the oscillator reaches 6.4 × 10-13 at a 1 s measurement time. Our system is expected to provide an ultralow-noise microwave oscillator for future radar systems and the next generation of wireless networks. © 2024 American Chemical Society.
  Accession Number: 20241215760586
• Record 269 of
  
  Title:Evaporation characteristics of Er3+-doped silica fiber and its application in the preparation of whispering gallery mode lasers
  
  Author(s):Li, Angzhen(1); Ward, Jonathan M.(2); Tian, Ke(3,4); Yu, Jibo(5); She, Shengfei(6); Hou, Chaoqi(6); Guo, Haitao(6); Chormaic, Síle Nic(4,7); Wang, Pengfei(3)
  Source: Optics Express  Volume: 32  Issue: 3  DOI: 10.1364/OE.509662  Published: January 29, 2024  
  Abstract:In this work, the concentration of rare-earth ions in doped silica whispering gallery lasers (WGLs) is controlled by evaporation. The fabrication of WGLs is used to experimentally evaluate the evaporation rate (mol/µm) and ratio (mol/mol) of erbium and silica lost from a doped fiber during heating. Fixed lengths of doped silica fiber are spliced to different lengths of undoped fiber and then evaporated by feeding into the focus of a CO2 laser. During evaporation, erbium ions are precipitated in the doped silica fiber to control the erbium concentration in the remaining SiO2, which is melted into a microsphere. By increasing the length of the undoped section, a critical point is reached where effectively no ions remain in the glass microsphere. The critical point is found using the spectra of the whispering gallery modes in microspheres with equal sizes. From the critical point, it is estimated that, for a given CO2 laser power, 6.36 × 10−21 mol of Er3+ is lost during the evaporation process for every cubic micron of silica fiber. This is equivalent to 1.74 × 10−7 mol of Er3+ lost per mol of SiO2 evaporated. This result facilitates the control of the doping concentration in WGLs and provides insight into the kinetics of laser-induced evaporation of doped silica. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20240615502598
• Record 270 of
  
  Title:Enhancing the spatial resolution of time-of-flight based non-line-of-sight imaging via instrument response function deconvolution
  
  Author(s):Wang, Dingjie(1,2); Hao, Wei(1,3,4); Tian, Yuyuan(1,2); Xu, Weihao(1,2); Tian, Yuan(1,2); Cheng, Haihao(2,5); Chen, Songmao(1,3,4); Zhang, Ning(6); Zhu, Wen Hua(7); Su, Xiuqin(1,3,4)
  Source: Optics Express  Volume: 32  Issue: 7  DOI: 10.1364/OE.518767  Published: March 25, 2024  
  Abstract:Non-line-of-sight (NLOS) imaging retrieves the hidden scenes by utilizing the signals indirectly reflected by the relay wall. Benefiting from the picosecond-level timing accuracy, time-correlated single photon counting (TCSPC) based NLOS imaging can achieve theoretical spatial resolutions up to millimeter level. However, in practical applications, the total temporal resolution (also known as total time jitter, TTJ) of most current TCSPC systems exceeds hundreds of picoseconds due to the combined effects of multiple electronic devices, which restricts the underlying spatial resolution of NLOS imaging. In this paper, an instrument response function deconvolution (IRF-DC) method is proposed to overcome the constraints of a TCSPC system s TTJ on the spatial resolution of NLOS imaging. Specifically, we model the transient measurements as Poisson convolution process with the normalized IRF as convolution kernel, and solve the inverse problem with iterative deconvolution algorithm, which significantly improves the spatial resolution of NLOS imaging after reconstruction. Numerical simulations show that the IRF-DC facilitates light-cone transform and frequency-wavenumber migration solver to achieve successful reconstruction even when the system s TTJ reaches 1200 ps, which is equivalent to what was previously possible when TTJ was about 200 ps. In addition, the IRF-DC produces satisfactory reconstruction outcomes when the signal-To-noise ratio (SNR) is low. Furthermore, the effectiveness of the proposed method has also been experimentally verified. The proposed IRF-DC method is highly applicable and efficient, which may promote the development of high-resolution NLOS imaging. © 2024 Optica Publishing Group (formerly OSA). All rights reserved.
  Accession Number: 20241415837517
• Record 271 of
  
  Title:Scalable parallel ultrafast optical random bit generation based on a single chaotic microcomb
  
  Author(s):Li, Pu(1,2,3); Li, Qizhi(4); Tang, Wenye(4); Wang, Weiqiang(5); Zhang, Wenfu(5); Little, Brent E.(5); Chu, Sai Tek(6); Shore, K. Alan(7); Qin, Yuwen(1,2,3); Wang, Yuncai(1,2,3)
  Source: Light: Science and Applications  Volume: 13  Issue: 1  DOI: 10.1038/s41377-024-01411-7  Published: December 2024  
  Abstract:Random bit generators are critical for information security, cryptography, stochastic modeling, and simulations. Speed and scalability are key challenges faced by current physical random bit generation. Herein, we propose a massively parallel scheme for ultrafast random bit generation towards rates of order 100 terabit per second based on a single micro-ring resonator. A modulation-instability-driven chaotic comb in a micro-ring resonator enables the simultaneous generation of hundreds of independent and unbiased random bit streams. A proof-of-concept experiment demonstrates that using our method, random bit streams beyond 2 terabit per second can be successfully generated with only 7 comb lines. This bit rate can be easily enhanced by further increasing the number of comb lines used. Our approach provides a chip-scale solution to random bit generation for secure communication and high-performance computation, and offers superhigh speed and large scalability. © The Author(s) 2024.
  Accession Number: 20241015704601
• Record 272 of
  
  Title:Polarization-Based Enhancement for Oceanic Constituents and Inherent Optical Properties (Iops) Retrieval from Multi-Angular Polarimetric Measurements Over Global Oceans
  
  Author(s):Liu, Jia(1,2,3,4); Li, Chunxia(5); He, Xianqiang(3); Chen, Tieqiao(2); Jia, Xinyin(2); Bai, Yan(3); Liu, Dong(6); Liu, Yupeng(1); Yang, Wentao(7); Wang, Yihao(2); Zhang, Geng(2); Li, Siyuan(2); Hu, Bingliang(2); Pan, Delu(3)
  Source: SSRN  Volume:   Issue:   DOI: 10.2139/ssrn.4803997  Published: April 23, 2024  
  Abstract:Multi-angle polarization characteristics of water-leaving radiation, which contain rich information on oceanic constituents and inherent optical properties (IOPs), have often been neglected. In this study, global radiative transfer (RT) simulations for the polarization characteristics of water-leaving radiance (Lw) were performed using the vector radiative transfer model for a coupled ocean-atmosphere system (PCOART). And, a global polarization-based algorithm for retrieving oceanic constituents and inherent optical properties (IOPs) was developed, employing the Fully Connected U-Net (FCUN). The retrieval performance of the algorithm was then analyzed using in-situ measurements collected during the Qiandao Lake field campaign. Results indicated that the low degrees of polarization (DOP) at short blue bands at solar zenith angle of 0° predominantly occurred in the tropical and subtropical oceans, with the lowest DOP value of 0.0176 observed in the extra oligotrophic subtropical gyres. The global mean absolute percentage error (MAPE) of the FCUN predictions compared to RT simulations for oceanic constituents (Chla, ag(443), NAP) and IOPs (a, b, aph, bph, aNAP, bNAP, bb, bbph, bbNAP) at 443 nm were 6.24%, 3.90%, 10.65%, 2.85%, 3.15%, 3.79%, 4.42%, 3.90%, 3.90%, 3.13%, 4.44%, and 3.90%, respectively, with mean global MAPE values of 4.52%. Additionally, the FCUN model’s predictions were consistent with RT simulation inputs under various random instrument noise conditions, with mean global MAPE values of 6.74% and 8.84% for those 12 retrieved parameters, respectively. Moreover, the retrieval performance analysis of FCUN on the in-situ measurements was performed with MAPE for Chla, a, aph, bb at 443 nm of 31.80%, 29.65%, 34.87%, and 43.04%, respectively. The importance of multi-angles polarization observations of Lw for ocean constituents and IOPs retrieval were also examined with the global mean MAPE decreasing from 16.91% to 1.48% as the observation angles increasing. Overall, the global polarization-based inversion model exhibited substantial potential for the oceanic constituents and IOPs retrieval of using multi-angle polarimetry. © 2024, The Authors. All rights reserved.
  Accession Number: 20240169237
• Record 273 of
  
  Title:Space advanced technology demonstration satellite
  
  Author(s):Zhang, XiaoFeng(1); Chen, Wen(1); Zhu, XiaoCheng(1); Meng, Na(1); He, JunWang(1); Bi, XingZi(1); Zhang, YongHe(1); Shi, Qi(1); Li, Fei(1); Liu, Rui(1); Feng, ZhengGong(1); Liu, Liu(1); Li, JinSong(1); Wu, HaiChen(1); Xu, DongXiao(1); Li, TaiJie(1); Huang, JiangJiang(1); Liu, Shuo(1); Li, TianTong(1); Yu, XianSheng(1); Gao, Yang(1); Zhou, Heng(1); Ban, HanYu(1); Zhang, YanLi(1); Zhang, YueTing(1); Yang, YingQuan(1); He, Tao(1); Duan, XuLiang(1); Chen, Xin(1); Wang, YaMin(1); Sun, AnTai(1); Zhang, KuoXiang(1); Sun, Ying(1); Wang, YaoBin(1); Fan, ChengCheng(1); Xiong, ShaoLin(2); Li, XinQiao(2); Wen, XiangYang(2); Ling, ZhiXing(3); Sun, XiaoJin(4); Zhang, Chen(3); Bai, XianYong(3); Wang, ZhanShan(5); Deng, YuanYong(3); Tian, Hui(6); Yang, JianFeng(7); Xue, HongBo(8); Sang, Peng(8); Liu, JinGuo(9); Zheng, HuiLong(10); Zhu, Xiang(8); He, JianWu(11); Li, Hui(12); Xu, LuXiang(13); Xu, ShuYan(14); Chen, WenWu(15); Liu, ZhenDong(15); Wang, ZhaoLi(16); Mao, XiangLong(7); Gao, Rong(7); Li, ZongXuan(17); Ding, GuoPeng(1); Wang, XinYu(1); Dou, RunJiang(18); Weng, LuBin(19); Luo, Hao(20); Wang, YaPing(1); Liang, XianFeng(8); Fang, ZiRuo(1)
  Source: Science China Technological Sciences  Volume: 67  Issue: 1  DOI: 10.1007/s11431-023-2510-x  Published: January 2024  
  Abstract:The Space Advanced Technology demonstration satellite (SATech-01), a mission for low-cost space science and new technology experiments, organized by Chinese Academy of Sciences (CAS), was successfully launched into a Sun-synchronous orbit at an altitude of ∼500 km on July 27, 2022, from the Jiuquan Satellite Launch Centre. Serving as an experimental platform for space science exploration and the demonstration of advanced common technologies in orbit, SATech-01 is equipped with 16 experimental payloads, including the solar upper transition region imager (SUTRI), the lobster eye imager for astronomy (LEIA), the high energy burst searcher (HEBS), and a High Precision Magnetic Field Measurement System based on a CPT Magnetometer (CPT). It also incorporates an imager with freeform optics, an integrated thermal imaging sensor, and a multi-functional integrated imager, etc. This paper provides an overview of SATech-01, including a technical description of the satellite and its scientific payloads, along with their on-orbit performance. © 2023, Science China Press.
  Accession Number: 20240115304467
• Record 274 of
  
  Title:Multilevel-based algorithm for hyperspectral image interpretation
  
  Author(s):Qiu, Shi(1); Ye, Huping(2,3); Liao, Xiaohan(2,3,4); Zhang, Benyue(1); Zhang, Miao(1); Zeng, Zimu(1)
  Source: Computers and Electrical Engineering  Volume: 113  Issue:   DOI: 10.1016/j.compeleceng.2023.109033  Published: January 2024  
  Abstract:Hyperspectral imagery contains spatial and spectral information, which can reveal the material properties of the target while intuitively displaying its spatial attributes. It has been applied in target recognition, search and rescue, and other fields. However, manual detection inevitably leads to missed detections and false alarms, necessitating the assistance of artificial intelligence for detection. To address this, we propose the multilevel-based algorithm for hyperspectral image interpretation. 1) From the spatial and spectral dimensions, we propose a semantic segmentation algorithm based on multidimensional information fusion to achieve semantic segmentation. 2) From the semantic and textual representation dimensions, we introduce a context interpretation module based on visual attention. We construct both real and simulated databases to validate the effectiveness of the algorithm. Experimental results demonstrate that the average accuracy of semantic segmentation achieved by the proposed algorithm is 74.3%. Additionally, the BLEU1 score reaches 71.2, outperforming mainstream algorithms by 1.4. © 2023 Elsevier Ltd
  Accession Number: 20234915147747
• Record 275 of
  
  Title:Generation of subcycle isolated attosecond pulses by pumping ionizing gating
  
  Author(s):Wu, Zhaohui(1); Zeng, Xiaoming(1); Li, Zhaoli(1); Zhang, Zhimeng(1); Wang, Xiaodong(1); Wang, Xiao(1); Mu, Jie(1); Zuo, Yanlei(1); Su, Jingqin(1); Peng, Hao(2); Cao, Huabao(3); Fu, Yuxi(3); Riconda, C.(4); Weber, S.(5)
  Source: Physical Review Research  Volume: 6  Issue: 1  DOI: 10.1103/PhysRevResearch.6.013126  Published: January 2024  
  Abstract:We present an interesting approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a preexisting gas grating, creating a fast-extending plasma grating (FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a subcycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency up-conversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs from long picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6 ps, 1 μm pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%. These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
  Accession Number: 20240615527419
• Record 276 of
  
  Title:All-polarization-maintaining mode-locked Holmium-doped fiber laser based upon nonlinear polarization evolution
  
  Author(s):Tu, Lisha(1,2); Tang, Ziya(1); Li, Keyi(1); Wang, Jiachen(1); Lin, Hua(3); Zhang, Wenfei(1); Lue, Qitao(4); Guo, Chunyu(1); Ruan, Shuangchen(2)
  Source: Infrared Physics and Technology  Volume: 136  Issue:   DOI: 10.1016/j.infrared.2023.105054  Published: January 2024  
  Abstract:An all-polarization-maintaining, all-fiberized holmium (Ho) doped fiber laser mode-locked by nonlinear polarization evolution (NPE) is experimentally demonstrated for the first time. The NPE mechanism is realized via the combination of a polarizer and the cross-fusion of three sections of polarization maintaining (PM) fibers. With the appropriate manipulation of the splicing angles between the birefringent axes of the PM fibers, a highly stable mode locked operation is realized. The laser delivers stable dissipative-soliton resonance (DSR) pulses with a repetition rate of 10.34 MHz and an average power of 223.95 mW, corresponding to a pulse energy of 21.64 nJ and a peak power of 11 W. Furthermore, the output power test over 2 h implies superior stability of this design. The oscillator, performing the characteristics of self-starting, high pulse energy, and good stability, is attractive and promising for various practical application. © 2023
  Accession Number: 20240115320784