2024
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Record 433 of
Title:Simultaneous transmission of multi-format signals in the mid-infrared over free space
Author Full Names:Su, Yulong(1); Xue, Jiayi(1); zheng, Yunqiang(1,2); Wang, Wei(2); Tian, Wenlong(1); zhu, Jiangfeng(1)Source Title:Optics CommunicationsLanguage:EnglishDocument Type:Journal article (JA)Abstract:Mid-infrared (MIR) light within the 3–5 μm spectrum offers distinct advantages over the 1.5 μm band, particularly in adverse atmospheric conditions, rendering it a favorable option for free-space optical (FSO) communication. The transmission capacity within the 3–5 μm band is relatively low due to the immature state of its devices. In this study, we demonstrate multi-format signals FSO transmission with a total of 40 Gbps capacity in the 3 μm band, utilizing our developed MIR transmitter and receiver modules. These modules facilitate wavelength conversion between the 1.5 μm and 3 μm bands through the utilization of difference-frequency generation (DFG) effect. The MIR transmitter effectively produces three MIR signals: On-Off Keying (OOK), Binary Phase Shift Keying (BPSK), and Quadrature Phase Shift Keying (QPSK) optical signals. The generated MIR power is 7.8 dBm, covering a wavelength range from 3.5864 to 3.5885 μm. The MIR receiver regenerates the three format signals with a power of ?29.6 dBm. Relevant results of regenerated signal demodulation have been collected in detail, including bit error ratio (BER), constellation diagram, and eye diagram. The required powers for the 10 Gbps OOK, BPSK, and QPSK are ?37.82, ?40.24, and ?39.4 dBm at BER of 1 × 10?6. It is expected to further push the data capacity to the terabit-per-second level by adding more 1.5 μm band laser sources and using wider-bandwidth chirped nonlinear crystals. ? 2024 Elsevier B.V.Affiliations:(1) School of Optoelectronic Engineering, Xidian University, Xi'an; 710071, China; (2) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi'an; 710119, ChinaPublication Year:2024Volume:573Article Number:131019DOI Link:10.1016/j.optcom.2024.131019數(shù)據庫ID（收錄號）:20243516960710 -
Record 434 of
Title:439 MHz, 94 fs, low-threshold mode-locked all fiber ring laser
Author Full Names:Huang, Xiwei(1); Guo, Xiaoxiao(1); Li, Xiaohui(1); Tang, Xu(1); Zhang, Rui(1); Zhang, Yan(1); Wang, Yishan(2); Zhao, Wei(2)Source Title:Optics and Laser TechnologyLanguage:EnglishDocument Type:Journal article (JA)Abstract:Pulsed fiber lasers with high repetition rates play a crucial role in applications such as high-efficiency processing and bio-optical imaging. However, many ring fiber mode-locked lasers primarily focus on shortening the cavity length to achieve high repetition rate pulse output. Attention is often directed towards the gain fiber and cavity structure, with less consideration given to the challenge of increasing mode-locking threshold power. In this study, we present a high-repetition-rate annular all-fiber laser system with dispersion management. Through strategic adjustment of the intracavity dispersion away from the near-zero dispersion region and careful control of the intracavity gain strength, we have successfully lowered the mode-locking threshold power. This approach can generate pulses with a repetition rate of 439.71 MHz and a mode-locking threshold power of approximately 600 mW. Following pulse compression, the achieved pulse width is 94.8 fs. Its time-bandwidth product is 0.368. To our knowledge, this represents the highest fundamental repetition rate currently attained using a ring all-fiber resonator, accompanied by the lowest mode-locking threshold. Our work introduces a ring fiber laser system characterized by a low mode-locking threshold and a high repetition rate, offering a valuable method for achieving higher fundamental repetition rate pulses. ? 2024 Elsevier LtdAffiliations:(1) College of Physics and Information Technology, Shaanxi Normal University, Xi'an; 710062, China; (2) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, ChinaPublication Year:2024Volume:179Article Number:111336DOI Link:10.1016/j.optlastec.2024.111336數(shù)據庫ID（收錄號）:20242516285052 -
Record 435 of
Title:The deactivation effects of Nd3+ ion for 2.85 μm laser in Ho3+/Nd3+ co-doped fluorotellurite glass
Author Full Names:Feng, Shaohua(1,2); Zhu, Jun(1,2); Liu, Chengzhen(1,2); Xiao, Yang(1,2); Cai, Liyang(1,2); Xu, Yantao(1,2); Xiao, Xusheng(1,2); Guo, Haitao(1,2,3)Source Title:Journal of LuminescenceLanguage:EnglishDocument Type:Journal article (JA)Abstract:The 2.85 μm band has garnered significant attention for its wide range of applications in the mid-infrared region, and Ho3+ doped fluorotellurite fiber shows great promise as a gain medium for the 2.85 μm fiber laser. To achieve efficient population inversion for Ho3+ ions at 2.85 μm, Ho3+/Nd3+ co-doped fluorotellurite glasses with low hydroxyl were synthesized. The deactivation effect of Nd3+ ions to Ho3+: 5I7 levels was investigated through emission spectra and lifetime decay curves under 890 nm excitation. The results show that Nd3+ ions can effectively quench the Ho3+: 2.05 μm emission and help the Ho3+: 5I6 → 5I7 transition to overcome the bottleneck of particle population inversion. Ultimately, the particle population inversion corresponding to 2.85 μm luminescence was realized in the Ho3+/Nd3+ co-doped fluorotellurite glass, and indicates that a maximum of 1.64 W laser at 2.85 μm with a slope efficiency of 8.72 % can be realized under 890 nm pump by numerical simulations. ? 2023 Elsevier B.V.Affiliations:(1) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences (CAS), Shaanxi, Xi'an; 710119, China; (2) Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing; 100049, China; (3) Collaborative Innovation Center of Extreme Optics, Shanxi University, Shanxi, Taiyuan; 030006, ChinaPublication Year:2024Volume:266Article Number:120308DOI Link:10.1016/j.jlumin.2023.120308數(shù)據庫ID（收錄號）:20240215352216 -
Record 436 of
Title:Dual-parameter femtosecond mode-locking pulse generation in partially shared all-polarization-maintaining fiber Y-shaped oscillator with a single saturable absorber
Author Full Names:Bai, Chen(1); Feng, Ye(2); Zhang, Weiguang(1); Zhang, Junying(1); Zhang, Tong(2); Mei, Chao(3); Liu, Pandi(4); Fan, Zhaojin(1); Qian, Jiangxiao(1); Yu, Jia(1)Source Title:Optics and Laser TechnologyLanguage:EnglishDocument Type:Journal article (JA)Abstract:We present a design of a mode-locked fiber laser based on a polarization-maintaining (PM) Y-shaped fiber structure, which employs a single semiconductor saturable absorber mirror (SESAM) and a common polarization beam combiner (PBC) to achieve dual- parameter mode-locking femtosecond pulse in two orthogonal polarization states. The two output pulses have different characteristics, such as repetition frequency (87.3 MHz and 91.3 MHz), average output powers (2.1 mW and 1.9 mW), pulse durations (299 fs and 377 fs) and spectral profiles (centered at 1565.6 nm and 1563.6 nm with spectral width of 9.96 nm and 9.93 nm). The properties of the two pulses are experimentally characterized and their potential applications in areas such as bistable frequency lasers and dual femtosecond optical frequency comb is discussed. ? 2023 Elsevier LtdAffiliations:(1) School of Optoelectronic Engineering, Xi'an Technological University, Xi'an; 710021, China; (2) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China; (3) Department of Aircraft Optical Imaging and Measurement Technology, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China; (4) School of Science, Xi'an Shiyou University, Xi'an; 710065, ChinaPublication Year:2024Volume:169Article Number:110021DOI Link:10.1016/j.optlastec.2023.110021數(shù)據庫ID（收錄號）:20233614695327 -
Record 437 of
Title:Noise Image Processing Algorithm for a Low-light EBCMOS Acquisition System Based on FPGA
Author Full Names:Cao, Yi(1,2); Zhu, Xiangping(1); Zhang, Xiaomo(1,2); Zhao, Wei(1); Ma, Jun(3)Source Title:Guangzi Xuebao/Acta Photonica SinicaLanguage:ChineseDocument Type:Journal article (JA)Abstract:The development of Electron-Bombarded Complementary Metal-Oxide-Semiconductor (EBCMOS)technology marks a significant advancement in image sensors, particularly enhancing low-light and night vision applications. This paper addresses challenges in device development due to material and manufacturing imperfections that introduce complex noise into night vision imagery. Additionally, it highlights the drawbacks of traditional software-based image processing platforms, including their low real-time performance and high operational costs.An analysis of low-light imaging characteristics of EBCMOS, developed by the Xi'an Institute of Optics and Mechanics, is presented. This research introduces a multistage pulse noise suppression and edge enhancement algorithm, designed on a Xilinx-FPGA platform, tailored to tackle mixed noises such as Poisson noise, salt-and-pepper noise, and speckle noise prevalent in low-light conditions. EBCMOS sensors are distinctive in their ability to enhance visibility in dark environments through an electron-bombarding mechanism that amplifies signals before CMOS processing. This capability is crucial for applications requiring high-quality night vision, such as security surveillance and wildlife monitoring. The imperfections in materials and fabrication processes can result in various noise types, degrading image quality and obscuring critical details.The paper details a sophisticated FPGA-based algorithm that leverages modern processing power to efficiently reduce noise while preserving important image details. This is achieved through advanced noise reduction techniques that specifically target the unique characteristics of each noise type, improving upon traditional methods like median filtering and Gaussian blurring. Experimental results show that this algorithm enhances the Peak Signal-to-Noise Ratio (PSNR)by 11.37% over median filtering and 26.64% over Gaussian blurring.Moreover, the processing speed for a single image frame is improved approximately 21 times compared to software platforms on high-end processors, demonstrating the algorithm's capability to handle real-time image processing tasks efficiently. This not only suggests potential cost reductions but also supports the integration and miniaturization of wearable night vision devices.In summary, this study provides significant insights into the benefits of FPGA-based image processing for EBCMOS technology in night vision applications. The advancements facilitate more effective and efficient night vision systems and promote the development of integrated, lightweight wearable devices, offering substantial benefits for both military and civilian uses. ? 2024 Chinese Optical Society. All rights reserved.Affiliations:(1) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, China; (2) University of Chinese Academy of Sciences, Beijing; 100049, China; (3) Xi'an Institute of Atomic Precision Manufacturing Technology Co., Ltd., Xi'an; 710110, ChinaPublication Year:2024Volume:53Issue:11Article Number:1110002DOI Link:10.3788/gzxb20245311.1110002數(shù)據庫ID（收錄號）:20245117548518 -
Record 438 of
Title:A compact 51.6-W, 26-μJ, Yb-doped all-fiber integrated CPA system through quasi-rectangular pulse pre-shaping
Author Full Names:Li, Qianglong(1,2,3); Li, Feng(1); Liu, Hongjun(1); Zhao, Wei(1); Zhao, Hualong(1); Wang, Yishan(1); Wen, Wenlong(1); Cao, Xue(1,2,3); Si, Jinhai(2)Source Title:Optics and Laser TechnologyLanguage:EnglishDocument Type:Journal article (JA)Abstract:A compact 51.6-W, 26-μJ all-fiber integrated Yb-doped femtosecond laser source with pulse durations of 692 fs despite ～18π nonlinear phase shift accumulation in the main amplifier is demonstrated by using fiber quasi-rectangular pulse pre-shaping. The numerical results are in good agreement with the experiment. Due to the advantages of an all-fiber spliced structure and a minimal pulse stretching ratio (from 26.3 ps to ～70 ps), just a small size of gratings and a short separation distance between the two gratings in the compressor is required. Therefore, the laser source is exceedingly compact, robust, cost-effective, and easy to assemble. This technique is anticipated to accelerate the use of fiber femtosecond lasers in industrial applications. ? 2023 Elsevier LtdAffiliations:(1) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Shaanxi, Xi'an; 710119, China; (2) School of Electronic and Information Engineering, Xi'an Jiaotong University, Shaanxi, Xi'an; 710049, China; (3) University of Chinese Academy of Sciences, Beijing; 100049, ChinaPublication Year:2024Volume:170Article Number:110300DOI Link:10.1016/j.optlastec.2023.110300數(shù)據庫ID（收錄號）:20234515013310 -
Record 439 of
Title:Experimental Analysis of Coherent Velocity Measurement Based on Near-infrared Single-element SPAD Detector
Author Full Names:Li, Bin(1); Wang, Xiaofang(2,3); Kang, Yan(2); Yue, Yazhou(1); Li, Weiwei(2,3); Zhang, Yixin(1); Lei, Hongjie(1); Zhang, Tongyi(2,3)Source Title:Guangzi Xuebao/Acta Photonica SinicaLanguage:ChineseDocument Type:Journal article (JA)Abstract:Coherent lidar has advantages of suppressing background noise such as sunlight and detecting sensitivity close to shot noise limit. It is widely used in civil and defense fields such as wind detection，velocity measurement and military target detection. Coherent detection can be divided into heterodyne detection to extract frequency information and homodyne detection to extract phase information. For velocity measurement，heterodyne detection is usually used to extract the Doppler frequency shift of the echo laser from a moving target，and then the velocity of target is retrieved. Conventional heterodyne lidar adopt normal optical detectors，such as PIN detectors，which have limited detection sensitivity for a small number of echo photons. And generally，strong local oscillator laser power is required to suppress thermal and circuit noise，but excessive local oscillator is likely to generate excess shot noise. With the development of Single Photon Avalanche Diode（SPAD）detector with low circuit noise，it not only provides a way for the detection of a small number of echo photons，but also makes it possible to realize heterodyne detection with a weak local oscillator. Researchers have successively adopted InGaAs SPAD array detectors and superconducting nanowire single-photon detectors for near-infrared spectrum， single-element Si SPAD detectors and MPPC detectors for visible spectrum，but there have been few experimental research on heterodyne detection with single-element InGaAs SPAD detector. The heterodyne lidar based on near-infrared SPAD can be integrated in all-fiber structure with an operating wavelength of 1.5 μm，which makes it more suitable for practical working platforms such as airborne. Although the count rate dynamic range of the single-element SPAD is not as good as that of the SPAD array，the current disadvantages of SPAD array，such as low pixel fill-factor，poor uniformity of pixel performance（e.g.，hot pixel），and slow speed of data readout，limit its performance to a certain extent. Besides，compared with superconducting nanowire single-photon detectors，single-element near-infrared SPAD do not require extremely complex and bulky cooling system. Therefore，we established a heterodyne velocimetry experimental system based on a 1.5 μm fiber laser and a single-element InGaAs SPAD detector to analyze the influence of SPAD's dead time，dark count rate and photon count rate for the extracting of beat frequency. The output laser was shifted by 40 MHz using an Acousto-optic Frequency Shifter（AOFS）to simulate the Doppler frequency shift of the echo laser from a moving target. Then，under the experimental set up of 1 μs dead time and 1 ms data acquisition time，we analyzed the influence of different photon count rates on the SNR of the beat frequency spectrum under SPAD's dark count rates of 1.8 kHz，54.4 kHz and 194.4 kHz. The experimental results show that，the SNR increases gradually and then tends to be stable with the increase of the photon count rate. When the photon count rate is close to saturation，harmonic frequency components appear in the low-frequency area of the frequency spectrum as well as the two side regions centered on the beat frequency. The harmonic frequency spacing is basically equal to the photon count rate. The optimal photon count rate which is slightly affected by harmonics is about 90% of saturation count rate of SPAD detector. In addition，as the dark count rate increases，the photon count rate required to extract the beat frequency signal is higher. The experimental results can provide a reference for the development and practical application of all-fiber single-photon Doppler velocity measurement lidar technology. ? 2024 Chinese Optical Society. All rights reserved.Affiliations:(1) Xi'an Flight Automatic Control Research Institute, Aviation Industry Corporation of China, Xi'an; 710065, China; (2) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, China; (3) University of Chinese Academy of Sciences, Beijing; 100049, ChinaPublication Year:2024Volume:53Issue:1Article Number:0104001DOI Link:10.3788/gzxb20245301.0104001數(shù)據庫ID（收錄號）:20240815582095 -
Record 440 of
Title:Color Non-line-of-sight Imaging Based on Time-correlated Single Photon Counting
Author Full Names:Li, Weiwei(1,2); Zhang, Tongyi(1,2); Kang, Yan(1); Xue, Ruikai(1,2); Wang, Xiaofang(1,2); Liang, Jintao(1,2); Li, Lifei(1)Source Title:Guangzi Xuebao/Acta Photonica SinicaLanguage:ChineseDocument Type:Journal article (JA)Abstract:Non-Line-Of-Sight（NLOS） imaging is a special optical imaging technique. It refers to the technique of reconstructing an image of an object in the event of an occlusion between the imaging system and an object that cannot be directly observed. It is to collect and analyze the photon signal returned from the target through the intermediate surface（such as wall，floor，etc.），to realize the image reconstruction of the target scene. NLOS imaging can be divided into active and passive depending on whether an active illumination source is used or not. Passive NLOS imaging systems rely primarily on the object itself emitting light or reflecting ambient light for imaging. Active NLOS imaging systems generally use a laser source for active illumination，it can obtain 3D image of the NLOS target through collecting time-resolution photon data. With the development of semiconductor single-photon detectors，Single-Photon Avalanche Photodiode （SPAD） detectors have gradually been widely used in active NLOS imaging technology due to their advantages of single photon detection sensitivity and picosecond temporal resolution，small size and low power consumption. However，in previous studies，researchers always used single-wavelength laser source to illuminate，and the reconstructed images of the targets only provide grayscale information of the target. In this paper，we demonstrate a color NLOS imaging method based on Time-Correlated Single-Photon Counting（TCSPC）and multi-wavelength laser illumination. First，we built a NLOS imaging system using confocal optical path mode，adopt a SPAD detector and a picosecond multi-wavelength pulsed laser. Then，the phasor field virtual wave algorithm is used to reconstruct the data collected by the three wavelength channels of 620±1.5 nm，532±1.5 nm and 485±1.5 nm，respectively. Finally，the three images obtained through different wavelength channels are synthesized to obtain a color NLOS image. In the experiments，targets containing different color information were selected for color NLOS imaging verification. The emitting laser repetition rate was set to 9.73 MHz，and the average power of the three wavelength lasers of 620 nm，532 nm，and 485 nm were 255.9 μW，100.8 μW，and 179.7 μW，respectively. A Silicon SPAD with a time jitter of 40 ps was used for echo photon detection. A 45 cm×45 cm wooden board with white wallpaper on its surface was used as the intermediate wall. The intermediate wall was 1 m away from the NLOS imaging system，and the target was 0.2 m away from the intermediate wall. The laser beam was controlled to scan 20×20 pixels on the intermediate wall and the interval between scanning points is 2 cm. The single point scanning time is 20 s. Under the above experimental parameter settings，NLOS imaging was performed on two targets containing four colors of red，white，yellow，and orange. By analyzing the PSNR of the imaging results，it can be obtained that the PSNRs of the 620 nm channel，the 532 nm channel，the 485 nm channel，and the synthetic color NLOS image are 7.9 dB，7.4 dB，6.7 dB，and 9.2 dB，respectively. This proves that the complementary detection of the three wavelengths can be used to obtain color NLOS imaging results with enhanced image quality. In summary，our proposed color NLOS imaging method can reconstruct the color image of complex NLOS targets with white，red，yellow and orange color features. Meanwhile，the complementarity of multi-wavelength detection can restore the 3D NLOS image with more complete details，which further expands the information dimension of NLOS imaging technology. In the future，it is planned to design a beam splitting system for the back-end receiving optical path and increase the number of SPAD detectors to detect more wavelengths simultaneously，so as to achieve high-efficiency TCSPC color non-line-of-sight imaging. ? 2024 Chinese Optical Society. All rights reserved.Affiliations:(1) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an; 710119, China; (2) University of Chinese Academy of Sciences, Beijing; 100049, ChinaPublication Year:2024Volume:53Issue:11Article Number:1111001DOI Link:10.3788/gzxb20245311.1111001數(shù)據庫ID（收錄號）:20245117558412 -
Record 441 of
Title:A 90 SrHfO 3 -based betavoltaic/beta-photovoltaic dual-effect integrated nuclear battery
Author Full Names:Cui, Qiming(1); Lu, Jingbin(1); Zhang, Yu(1); Yuan, Xinxu(1); Li, Chengqian(1); Zhao, Yang(1); Zheng, Renzhou(2); Li, Xiaoyi(1); Liu, Yuxin(1); Liu, Xinrui(1)Source Title:Applied Physics LettersLanguage:EnglishDocument Type:Journal article (JA)Abstract:In this paper, the secondary conversion idea is used to reduce the self-absorption effect of the radioactive source by combining the radioactive source with the scintillation material, so as to enhance the energy conversion efficiency of the battery. A theoretical model of a dual-effect integrated nuclear battery based on 90 SrHfO 3 doped with Ce is proposed. The emission photon and electron spectra of the β -luminescent integrated radioactive source 90 SrHfO 3 have been calculated by GEANT4. The average outgoing electron energy of SrHfO3 was calculated, and the thickness of the energy reducing material was determined. The effect of structural parameters of GaAs materials on the dual-effect integrated nuclear battery was analyzed to obtain the optimal output performance according to theoretical calculation. From the perspective of conversion efficiency, the activity density and thickness of 90 SrHfO 3 are determined to be 1.6 Ci/cm2 and 53.6 μ m. At this time, the thickness of SrHfO3 is 1.28 mm. The total maximum output power density of the optimized dual-effect integrated nuclear battery is 9.31 μ W/cm2, and the energy conversion efficiency is 0.18 % . At this point, the doping concentrations of GaAs are N a = 1.26 × 1017 cm?3 and N d = 6.31 × 1018 cm?3, and x j is 0.05 μ m . Compared with nonintegrated batteries, the output performance is significantly improved. ? 2024 Author(s).Affiliations:(1) College of Physics, Jilin University, Changchun; 130012, China; (2) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, ChinaPublication Year:2024Volume:125Issue:16Article Number:163902DOI Link:10.1063/5.0230622數(shù)據庫ID（收錄號）:20244317252392 -
Record 442 of
Title:Optical diffraction tomography based on quadriwave lateral shearing interferometry
Author Full Names:Yuan, Xun(1,2); Min, Junwei(1); Zhou, Yuan(1,2); Xue, Yuge(1,2); Bai, Chen(1); Li, Manman(1); Xu, Xiaohao(1); Yao, Baoli(1,2)Source Title:Optics and Laser TechnologyLanguage:EnglishDocument Type:Journal article (JA)Abstract:Optical diffraction tomography (ODT) is an emerging microscopy that enables quantitatively three-dimensional (3D) refractive index (RI) mapping of subcellular structure inside biological cells without staining. Due to the noninvasive, label-free, and quantitative imaging capability, ODT has become an important technique in the fields of cell biology, biophysics, hematology, and so on. It is customary to acquire a set of two-dimensional (2D) phase images of a transparent sample from different illumination angles by using the classical Mach-Zehnder interferometry (MZI), and then numerically reconstruct the 3D RI distribution of the sample via appropriate tomographic algorithms. However, due to the limited stability of MZI, the cumulative measured phase errors reduce the accuracy of the reconstructed RI. Here, we propose a common-path ODT based on quadriwave lateral shearing interferometry (QLSI), referred as Q-ODT. In QLSI, the object beam carrying the phase information of sample is divided into four copies by a specially designed 2D diffraction optical element, then the diffracted waves interfere with each other to form the interferogram at the image plane. The complex amplitude map of the object is quantitatively retrieved from the single-shot interferogram by using a Fourier analysis algorithm and a 2D phase gradient integration. A spatial light modulator is employed to ensure high-precision illumination angle scanning without mechanical motion by addressing a series of different periods and orientations blazed gratings. The average fluctuation of the measured phases of a test polystyrene bead by acquiring 300 interferograms in 12 s presents 7.6 mrad, surpassing the conventional MZI-based ODT. The 3D RI distribution of the bead reconstructed from 145 complex amplitude maps via multi-illumination angles with a maximum angle of 70° matches the manufacturer's specification well, demonstrating the high accuracy of the 3D RI imaging capability of the Q-ODT. The lateral and axial resolutions of the 3D RI reconstruction were measured to be 306 ± 21 nm and 825 ± 34 nm, respectively. The proposed Q-ODT method successfully reconstructed the intracellular structure of the biological specimens of Eudorina elegans and mouse bone mesenchymal stem cells (BMSC). The Q-ODT offers a new route towards 3D RI imaging for label-free transparent samples in biomedical research. ? 2024 Elsevier LtdAffiliations:(1) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, China; (2) University of Chinese Academy of Sciences, Beijing; 100049, ChinaPublication Year:2024Volume:177Article Number:111124DOI Link:10.1016/j.optlastec.2024.111124數(shù)據庫ID（收錄號）:20241916034871 -
Record 443 of
Title:A different view on the deactivation process of 3-hydroxy-salicylidene-methylamine system
Author Full Names:Han, Guoxia(1); Wei, Hongyan(2); Yu, Xianghua(3); Zhang, Jialing(1); Ma, Yanbin(1); Liu, Peng(1)Source Title:Chemical Physics LettersLanguage:EnglishDocument Type:Journal article (JA)Abstract:Schiff bases stand out as a highly significant class of photochromic materials with widespread applications. The exploration of their photochromic mechanisms has garnered substantial interest over the past decades. In this work, we investigated the photochromic mechanism of 3-hydroxy-salicylidene methylamine (3-OH-SMA) by high-level electronic structure calculations and on-the-fly excited state dynamics simulations. Our investigation revealed the identification of three minimum energy conical intersections between S1 and S0 states, while only the one characterized by the central C = N bond twisting motion was involved in the deactivation process. This finding contrasts with previous reports, suggesting that the excited state intramolecular proton transfer (ESIPT) process was the main reaction channel in 3-OH-SMA. The proposed new decay mechanism provides valuable theoretical insights, paving the way for the further enhancement or rational design of photochromic materials. ? 2023 Elsevier B.V.Affiliations:(1) College of Science, China University of Petroleum (East China), Shandong, Qingdao; 266580, China; (2) College of Physics and Optoelectronics, Taiyuan University of Technology, Shanxi, Taiyuan; 030024, China; (3) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, ChinaPublication Year:2024Volume:835Article Number:141004DOI Link:10.1016/j.cplett.2023.141004數(shù)據庫ID（收錄號）:20235015192341 -
Record 444 of
Title:Optical Torques Induced by the Spirally Polarized Vector Beam
Author Full Names:Niu, Ruixin(1,2); Gao, Wenyu(1,2); Zhang, Qiang(1,2); Zhang, Yanan(1,2); Zhou, Yuan(1,2); Li, Manman(1); Xu, Xiaohao(1,2); Yan, Shaohui(1); Yao, Baoli(1,2)Source Title:Guangzi Xuebao/Acta Photonica SinicaLanguage:ChineseDocument Type:Journal article (JA)Abstract:The Imaginary Poynting Momentum （IPM） is associated to the imaginary part of the well-known complex Poynting vector. When light fields interact with matter，researchers usually pay attention to the real part of the complex Poynting vector，while neglect its imaginary part. However，the real Poynting vector describes only a portion of the physical mechanism underlying light-particle interaction. Recent theoretical and experimental breakthrough have been made in the study of the IPM force，which has gained increasing interest that the IPM force is independent of the optical radiation pressure and intensity gradient force. It provides a new degree of freedom for optical micromanipulation with structured light，such as vector beams，evanescent and two-wave interference fields. The IPM force can be detected directly with a Mie particle in the tightly focused Spirally Polarized Vector Beam（SPVB）when the IPM appears in the azimuthal direction. Nevertheless，the spinning optical torque caused by the vortex-like structure of IPM has not been investigated. In order to study the rotational manipulation of particles by this IPM vortex，we use the Finite-Difference Time-Domain（FDTD）method，to investigate the spinning optical torque acting on microparticles，illuminated by the SPVB，and to study the influence of the particle material properties on the torque. The cylindrical vector beam is constructed by the in-phase superposition of the radially and azimuthally polarized vector beam. When the angle of polarization is π/4，this cylindrical vector beam is the spirally polarized vector beam characterized by the IPM arising in the azimuthal direction. The FDTD method is a prevailing solution that can be used to solve Maxwell's equations and optomechanics for arbitrarily shaped particles. The scattering problem of arbitrary particles can be handled，so the FDTD method is characterized by high inclusivity and high accuracy. The spinning torque is computed rigorously based on the Maxwell stress tensor method，or the conservation of optical angular momentum of the total field. By changing the wavelength of the incident field as well as the size，shape and material of the particles，the spinning optical torque characteristics of the particles under the SPVB are analyzed comprehensively. The computation results show that this SPVB can induce the spinning optical torque，which drives the microparticle to spin about their own axis. For rod-like particles，the spinning optical torque increases first，and then decreases with the increase of incident wavelength. There is the phenomenon of resonance peaks explained by the multipole resonances induced in the particles. The spinning optical torque tends to increase first and then decrease with the increase of particle's length，and the spinning optical torque reaches the maximum value at particle's length around 2 μm. Moreover，it is found that，for the particles with complex geometrical structures（e.g.，equilateral-triangle，hexagonal and chiral structures），the spinning optical torque is at least one order of magnitude larger than that of the rod-shape particle，and the values and directions of the spinning optical torques are more varied. On complex geometrically structured particles of certain sizes and materials，due to the effect of resonance，there are overall large value and opposite direction for the spinning optical torques. The particles selected in this paper have some special shapes，but for generic isotropic particles，IPM can also induce them to spin. This reveals a new method for achieving light-driven microrotors，which does not rely on the optical angular momentum. The azimuthal IPM complements the spin and orbital angular momenta in terms of their rotational mechanical effects，which has potential applications in the field of optical micromanipulation and levitated optomechanics，especially in the realization of unusual optomechanical manifestations such as the negative or left-handed optical torque. ? 2024 Chinese Optical Society. All rights reserved.Affiliations:(1) State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an; 710119, China; (2) University of Chinese Academy of Sciences, Beijing; 100049, ChinaPublication Year:2024Volume:53Issue:11Article Number:1126001DOI Link:10.3788/gzxb20245311.1126001數(shù)據庫ID（收錄號）:20245117562978