2021
2021
-
Record 97 of
Title:The nonlinear optical properties of two-dimensional metal-organic framework
Author(s):Cheng, Xuemei(1,2); Yao, Jingjing(1); Zhang, Hui(3); Wang, Xing(2); Bai, Jintao(1)Source: Journal of Alloys and Compounds Volume: 855 Issue: DOI: 10.1016/j.jallcom.2020.157433 Published: February 25, 2021Abstract:We report the investigation on the nonlinear optical properties of two typical two-dimensional metal-organic frameworks (2D MOFs) - 2D Cu-MOF and Zn-MOF (copper/zinc 1,4-benzene dicarboxylate, CuBDC and ZnBDC) using spatial self-phase modulation (SSPM) and spatial cross-phase modulation (SXPM) methods. It is found that 2D Cu-MOF exhibits a large nonlinear optical coefficient n2=5.2010-11m2/Wandχ3=8.2410?11e.s.u. By contrast, no nonlinear optical effect was observed from 2D Zn-MOF under the same condition. The main reason is the Cu center of Cu-MOF has variable valence electrons and a vacant 3d atom orbit, which can form a conjugated system with organic ligands through the d-π interaction and therefore strengthen the nonlinear optical effect by the delocalization of π electrons. However, the Zn ion of Zn-MOF with fixed valence electrons and fully occupied d orbit makes it hard to produce observable nonlinear optical effect. Furthermore, we demonstrated the ability of 2D Cu-MOF in all-optical spatial light modulation and optical switch based on the principle of SXPM. This work sheds light on the physics of 2D MOFs in all-optical light modulation, providing an insight for rational design of 2D MOFs with high nonlinear optical coefficients in future. ? 2020 Elsevier B.V.Accession Number: 20204109318719 -
Record 98 of
Title:Background purification framework with extended morphological attribute profile for hyperspectral anomaly detection
Author(s):Huang, Ju(1,2); Liu, Kang(1,2); Xu, Mingliang(3); Perc, Matja?(4); Li, Xuelong(5,6)Source: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Volume: 14 Issue: DOI: 10.1109/JSTARS.2021.3103858 Published: 2021Abstract:Hyperspectral anomaly detection has attracted extensive interests for its wide use in military and civilian fields, and three main categories of detection methods have been developed successively over past few decades, including statistical model-based, representation-based, and deep-learning-based methods. Most of these algorithms are essentially trying to construct proper background profiles, which describe the characteristics of background and then identify the pixels that do not conform to the profiles as anomalies. Apparently, the crucial issue is how to build an accurate background profile; however, the background profiles constructed by existing methods are not accurate enough. In this article, a novel and universal background purification framework with extended morphological attribute profiles is proposed. It explores the spatial characteristic of image and removes suspect anomaly pixels from the image to obtain a purified background. Moreover, three detectors with this framework covering different categories are also developed. The experiments implemented on four real hyperspectral images demonstrate that the background purification framework is effective, universal, and suitable. Furthermore, compared with other popular algorithms, the detectors with the framework perform well in terms of accuracy and efficiency. ? This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/Accession Number: 20220211441070 -
Record 99 of
Title:Hyperspectral anomaly detection via super-resolution reconstruction with an attention mechanism
Author(s):Chong, Dan(1,2); Hu, Bingliang(1); Gao, Hao(3); Gao, Xiaohui(1)Source: Applied Optics Volume: 60 Issue: 26 DOI: 10.1364/AO.432704 Published: September 10, 2021Abstract:Hyperspectral anomaly detection aims to classify the anomalous objects in the scene. However, the spatial resolution of the hyperspectral images is relatively low, leading to inaccurate detection of abnormal pixels. Existing methods either ignore the low-resolution problem or leverage super-resolution models to reconstruct the global image to detect abnormal pixels.We claim that reconstructing super-resolution of the global image is unnecessary, while the area where the abnormal target is located should be paid more attention to be reconstructed. In this paper, we propose a super-resolution reconstruction with an attention mechanism for hyperspectral anomaly detection. Our method can automatically extract additional high-frequency information from low-spatial-resolution images and detect abnormal pixels simultaneously. Furthermore, the spatial-channel attention mechanism is adopted to select significant features for reconstructing super-resolution images by assigning different weights to different channels and different spatial-spectral locations. Finally, a regularized join loss function is proposed that balances different tasks by adjusting the relative weight. The experimental results on the public hyperspectral real datasets demonstrate that the proposed method outperforms the state-of-the-art methods. ? 2021 Optical Society of America.Accession Number: 20213710888744 -
Record 100 of
Title:Fiber interferometers for time-domain quantum optics
Author(s):MacLellan, Benjamin(1); Roztocki, Piotr(1,2); Islam, Mehedi(1); Reimer, Christian(1,3); Fischer, Bennet(1); Sciara, Stefania(1,4); Helsten, Robin(1); Jestin, Yoann(1,2); Cino, Alfonso(4); Chu, Sai T.(5); Little, Brent(6); Moss, David J.(7); Kues, Michael(8,9); Morandotti, Roberto(1,10)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: null Published: 2021Abstract:A novel method for stabilizing fiber interferometers based on frequency- and polarization-multiplexing enables unambiguous phase retrieval, long-term stability, and phase-independent performance. These capabilities allow for precise manipulation of time-bin quantum states in a low-complexity setup. ? OSA 2021, ? 2021 The Author(s)Accession Number: 20214711208454 -
Record 101 of
Title:Density saliency for clustered building detection and population capacity estimation
Author(s):Liu, Kang(1,2); Huang, Ju(1,2); Xu, Mingliang(3); Perc, Matja?(4); Li, Xuelong(5,6)Source: Neurocomputing Volume: 458 Issue: DOI: 10.1016/j.neucom.2021.06.002 Published: October 7, 2021Abstract:Building detection is a critically important task in the field of remote sensing and it is conducive to urban construction planning, disaster survey, shantytown modification, and emergency landing, it etc. However, few studies have focused on the task of the clustered building detection which is inescapable and challenging for some relatively low space resolution images. The appearance structures of those buildings are not clear enough for the single-building detection. Whereas, it has been found that the distributions of clustered buildings are mostly dense and cellular, while the backgrounds are not. This clue will be beneficial to the clustered building detection. Motivated by the fact above and other similar density estimation applications, this work mainly focuses on the information mining mechanism of dense and cellular structure. Firstly, we propose a concept of Clustered Building Detection (CBD), which contributes to develop clustered building detection techniques of remote sensing images. Secondly, a saliency estimation algorithm is proposed to mine the prior information for the clustered buildings. Thirdly and most notably, combining with the CBD and the density saliency map, a Population Capacity Estimation (PCE) method is presented. The PCE can be easily used to estimate the population carrying capacity of certain areas and future applied for national land resource management. Moreover, a Clustered Building Detection Dataset (CBDD) from Gaofen-2 satellite is annotated and contributed for the public research. The experimental results by the representative detection algorithms manifest the effectiveness for the clustered building detection. ? 2021 Elsevier B.V.Accession Number: 20212510544366 -
Record 102 of
Title:Fiber Interferometers for Time-domain Quantum Optics
Author(s):MacLellan, Benjamin(1); Roztocki, Piotr(1,2); Islam, Mehedi(1); Reimer, Christian(1,3); Fischer, Bennet(1); Sciara, Stefania(1,4); Helsten, Robin(1); Jestin, Yoann(1,2); Cino, Alfonso(4); Chu, Sai T.(5); Little, Brent(6); Moss, David J.(7); Kues, Michael(8,9); Morandotti, Roberto(1,10)Source: 2021 Conference on Lasers and Electro-Optics, CLEO 2021 - Proceedings Volume: Issue: DOI: null Published: May 2021Abstract:A novel method for stabilizing fiber interferometers based on frequency-and polarization-multiplexing enables unambiguous phase retrieval, long-term stability, and phase-independent performance. These capabilities allow for precise manipulation of time-bin quantum states in a low-complexity setup. ? 2021 OSA.Accession Number: 20214911280576 -
Record 103 of
Title:Autonomous on-chip interferometry for reconfigurable optical waveform generation
Author(s):Fischer, Bennet(1); Chemnitz, Mario(1); MacLellan, Benjamin(1); Roztocki, Piotr(1); Helsten, Robin(1); Wetzel, Benjamin(2); Little, Brent E.(3); Chu, Sai T.(4); Moss, David J.(5); Azana, Jose(1); Morandotti, Roberto(1,6)Source: Optica Volume: 8 Issue: 10 DOI: 10.1364/OPTICA.435435 Published: October 2021Abstract:The generation of user-defined optical temporal waveforms with picosecond resolution is an essential task for many applications, ranging fromtelecommunications to laser engineering.Realizing this functionality in an on-chip reconfigurable platformremains a significant challenge. Towards this goal, autonomous optimization methods are fundamental to counter fabrication imperfections and environmental variations, as well as to enable a wider range of accessible waveform shapes and durations. In this work, we introduce and demonstrate a self-adjusting on-chip optical pulse-shaper based on the concept of temporal coherence synthesis. The scheme enables on-the-fly reconfigurability of output optical waveforms by using an all-optical sampling technique in combination with an evolutionary optimization algorithm. We further show that particle-swarmoptimization can outperformmore commonly used algorithms in terms of convergence time.Hence, our system combines all key ingredients for realizing fully on-chip smart optical waveformgenerators for next-generation applications in telecommunications, laser engineering, and nonlinear optics. ? 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.Accession Number: 20214311055293 -
Record 104 of
Title:Monocular depth estimation based on a single image: A literature review
Author(s):Tian, Yuan(1,2); Hu, Xiaodong(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11720 Issue: DOI: 10.1117/12.2589510 Published: 2021Abstract:Monocular depth estimation is a very valuable but also very challenging problem. In order to solve this ill-posed problem, traditional approaches apply depth cues such as defocusing, atmospheric scattering and shading to estimate depth information and approaches based on machine learning apply frameworks such as MRF and data-driven learning. With the development of deep learning, the monocular depth estimation approaches based on CNN and other networks have achieved good results and gradually become the mainstream. In this paper, we summarize some typical and representative literature on monocular depth estimation based on a single image in the past two decades and depict our analysis involved in these approaches. In addition, this paper also analyzes and compares the results obtained by some typical approaches, which may provide some guidance for those who are interested in this field. ? 2021 SPIE.Accession Number: 20210809937521 -
Record 105 of
Title:Arbitrary Phase Access for Stable Fiber Interferometers
Author(s):Roztocki, Piotr(1,2); MacLellan, Benjamin(1); Islam, Mehedi(1); Reimer, Christian(1,3); Fischer, Bennet(1); Sciara, Stefania(1,4); Helsten, Robin(1); Jestin, Yoann(1,2); Cino, Alfonso(4); Chu, Sai T.(5); Little, Brent(6); Moss, David J.(7); Kues, Michael(1,8); Morandotti, Roberto(1,9)Source: Laser and Photonics Reviews Volume: 15 Issue: 7 DOI: 10.1002/lpor.202000524 Published: July 2021Abstract:Well-controlled yet practical systems that give access to interference effects are critical for established and new functionalities in ultrafast signal processing, quantum photonics, optical coherence characterization, etc. Optical fiber systems constitute a central platform for such technologies. However, harnessing optical interference in a versatile and stable manner remains technologically costly and challenging. Here, degrees of freedom native to optical fibers, i.e., polarization and frequency, are used to demonstrate an easily deployable technique for the retrieval and stabilization of the relative phase in fiber interferometric systems. The scheme gives access (without intricate device isolation) to ?3?π?rad error signal Allan deviation across 1 ms to 1.2 h integration times for all tested phases, ranging from 0 to 2π. More importantly, the phase-independence of this stability is shown across the full 2π range, granting access to arbitrary phase settings, central for, e.g., performing quantum projection measurements and coherent pulse recombination. Furthermore, the scheme is characterized with attenuated optical reference signals and single-photon detectors, and extended functionality is demonstrated through the use of pulsed reference signals (allowing time-multiplexing of both main and reference signals). Finally, the scheme is used to demonstrate radiofrequency-controlled interference of high-dimensional time-bin entangled states. ? 2021 The Authors. Laser & Photonics Reviews published by Wiley-VCH GmbHAccession Number: 20211810301185 -
Record 106 of
Title:Tracking control Scheme for photoelectric tracking platform with predictor-structure ESO
Author(s):Wang, Fan(1); Wang, Ranjun(1); Xie, Meilin(1); Liu, Peng(1); Jing, Feng(1); Liu, Bo(1)Source: Proceedings - 2021 International Conference on Machine Learning and Intelligent Systems Engineering, MLISE 2021 Volume: Issue: DOI: 10.1109/MLISE54096.2021.00028 Published: 2021Abstract:In this paper, a high-precision control scheme based on active disturbance rejection control (ADRC) with predictor-structure extended state observer (PESO) is developed to improve the tracking accuracy of a photoelectric tracking platform (PTP). ADRC controller is designed to estimation and compensation total disturbances which include both the external disturbances and the internal uncertain dynamics. The tracking loop of PTP is considered as an input-delay system through the designed composite control structure, then a PESO is proposed to obtain more accurate states and total disturbance. At the same time, the convergence of PESO is analyzed, and some simulations illustrate the effectiveness of PESO. Finally, the presented controller is realized on embedded microcontroller, and the contrast experiments are carried out. Experimental results show that the presented controller has excellent capability in error rejection, by which the effect of delay is effectively weakened, and the tracking accuracy of PTP is significantly improved. ? 2021 IEEE.Accession Number: 20220411520987 -
Record 107 of
Title:Progress of research on high energy laser component
Author(s):Shen, Zeyi(1); Xin, Wei(1); Song, Yang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11849 Issue: DOI: 10.1117/12.2598929 Published: 2021Abstract:Laser weapon is a complex system, which consists of laser, optical system, ATP (Acuisition Tracking Pointing)system, electronic control system and so on. It needs the close cooperation of structure, optics, electronics and other disciplines. Laser weapon has developed rapidly in recent years, and developed countries have increased investment in experiments. Laser weapon has the advantages of high cost-effectiveness ratio and light speed attack. It has been applied in vehicle, shipboard and airborne, and may develop into space application in the future. In recent years, drones play an increasingly important role in the battlefield. Laser weapon is a powerful weapon to deal with drones. Laser weapons can be classified into chemical lasers, solid-state lasers, free electron lasers and so on. Solid state laser will be an important direction of laser development in the future. ? 2021 SPIE.Accession Number: 20212810626511 -
Record 108 of
Title:Four-wave mixing in silicon-nanocrystal embedded high-index doped silica micro-ring resonator
Author(s):Li, Yuhua(1,2); Wang, Xiang(3); Davidson, Roy(3); Little, Brent E.(4); Chu, Sai Tak(2)Source: Journal of Semiconductors Volume: 42 Issue: 4 DOI: 10.1088/1674-4926/42/4/042302 Published: April 2021Abstract:A nonlinear integrated optical platform that allows the fabrication of waveguide circuits with different material composition, and at small dimensions, offers advantages in terms of field enhancement and increased interaction length, thereby facilitating the observation of nonlinear optics effects at a much lower power level. To enhance the nonlinearity of the conventional waveguide structure, in this work, we propose and demonstrate a microstructured waveguide where silicon rich layer is embedded in the core of the conventional waveguide in order to increase its nonlinearity. By embedding a 20 nm thin film of silicon nanocrystal (Si-nc), we achieve a twofold increase of the nonlinear parameter, γ. The linear relationship between the four-wave mixing conversion efficiency and pump power reveals the negligible nonlinear absorption and small dispersion in the micro-ring resonators. This simple approach of embedding an ultra-thin Si-nc layer into conventional high-index doped silica dramatically increases its nonlinear performance, and could potentially find applications in all-optical processing functions. ? 2021 Chinese Institute of Electronics.Accession Number: 20212010361044