2023

• Record 1 of
  
  Title:Direct sampling of ultrashort laser pulses using third-harmonic generation with perturbation in ambient air
  
  Author(s):Huang, Pei(1); Yuan, Hao(1,2); Cao, Huabao(1,2); Wang, Hushan(1,2); Wang, Xianglin(1,2); Wang, Yishan(1,2); Zhao, Wei(1,2); Fu, Yuxi(1,2)

  Source: Optics Letters  Volume: 48  Issue: 8  Article Number: null  DOI: 10.1364/OL.485665  Published: April 15, 2023  

  Abstract:We propose a simple and robust all-optical pulse sampling method to characterize the temporal profiles of ultrashort laser pulses. The method is based on a third-harmonic generation (THG) process with perturbation in ambient air, which requires no retrieval algorithm and can be potentially applied to electric field measurement. The method has been successfully used to characterize multi-cycle and few-cycle pulses with a spectral range from 800 nm to 2200 nm. Considering the broad phase-matching bandwidth of THG and extremely low dispersion of air, this method is suitable for ultrashort pulse characterization even for single-cycle pulses in the near- to mid-infrared range. Thus, the method provides a reliable and highly accessible approach for pulse measurement in ultrafast optics research. © 2023 Optica Publishing Group.

  Accession Number: 20231914070311
• Record 2 of
  
  Title:Progressive photon mapping algorithm for digital imaging of a space target
  
  Author(s):Li, Yaru(1,2,3); Zhou, Liang(1,3); Liu, Zhaohui(1,3); She, Wenji(1,3)
  Source: Applied Optics  Volume: 62  Issue: 26  Article Number: null  DOI: 10.1364/AO.495869  Published: September 10, 2023  
  Abstract:Space target imaging simulation holds great significance for the development of space-based imaging systems and the prediction of imaging tasks. Currently, commonly used rendering algorithms in space target imaging simulation suffer from issues such as radiance calculation results lacking actual physical significance and rendered images containing high-frequency noise. To address these issues, this study proposes a rendering algorithm based on progressive photon mapping in the context of space imaging scenarios, aiming to enhance the accuracy of energy calculations and image rendering for space targets. This algorithm generates multiple photon maps on the target surface through multiple iterations, retrieves photon information near the observation point based on these photon maps, and thus obtains the radiance of the observation direction vector. This study evaluates the quality of rendered images using no-reference image quality assessment algorithms. The results demonstrate that this algorithm can enhance image rendering quality in specific imaging scenarios, consequently improving the accuracy of space target recognition. By comparing the calculated values of this algorithm with the theoretical radiance values for diffuse material, the accuracy of the radiance calculation results of this algorithm is verified, which can provide significant reference values for the selection of backend detectors. © 2023 Optica Publishing Group.
  Accession Number: 20233914799104
• Record 3 of
  
  Title:Diffusion of electron clouds in high-speed ultraviolet photonic imaging detectors
  
  Author(s):Duan, Jinyao(1,2); Zheng, Jinkun(1,2); Yang, Yang(1,2); Song, Yuchao(3); Lai, Anpeng(3); Wang, Bo(1,2); Cao, Weiwei(1,2); Bai, Yonglin(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12959  Issue: null  Article Number: 129590Z  DOI: 10.1117/12.3007806  Published: 2023  
  Abstract:In this paper, we mainly study the problem of electron cloud diffusion in high-speed ultraviolet photonic imaging detectors. In this paper, the size of the electron cloud transmitted by the microchannel plate and the anode in the high-speed ultraviolet photon imaging detector is studied by simulation, including the bias angle, pore diameter, voltage (U) and distance between MCP and anode (l) on the electron cloud received by the anode. the diffusion radius of the electron cloud increases with the increase of the bias angle, and the voltage (U) and the distance (l) between the MCP and the anode on the electron cloud received by the anode. The research shows that the diffusion radius of the electron cloud increases with the increase of the bias angle, the diffusion radius of the electron cloud. When U is larger, the energy of electron cloud is also higher. When the voltage increases to 1900V, the electron movement speed increases linearly with the increase of U. Moreover, the diffusion distance of the electron cloud radius increases with the increase of the transmission distance l. When the distance is 2 mm, a maximum electron diffusion radius is obtained. When the bias angle is 10°, the pore diameter is 10um, the voltage is 2000V, and the distance l is 0.5mm, the diffusion ratio of the electron cloud is 5.5. © 2023 SPIE.
  Accession Number: 20240215330027
• Record 4 of
  
  Title:Design of Fourier ptychographic illuminator for single full-FOV reconstruction
  
  Author(s):Gao, Yuting(1,2,3); Pan, An(1,2); Gao, Huiqin(1,2); Wang, Aiye(1,2); Ma, Caiwen(2,3); Yao, Baoli(1,2)
  Source: Optics Express  Volume: 31  Issue: 18  Article Number: null  DOI: 10.1364/OE.500385  Published: August 1, 2023  
  Abstract:Fourier ptychographic microscopy (FPM) is a spatial-temporal-modulation high-throughput imaging technique via a sequential angle-varied LED illumination. Therefore, the illuminator is one of the key components and the design of this illuminator is significant. However, because of the property of spherical wave, partial coherence, and aperture-induced vignetting, the acquired images must be processed in blocks first, and rely on parallel reconstruction via a graphics processing unit (GPU). The high cost makes it unappealing compared with commercial whole slide imaging system via a low-cost central processing unit (CPU). Especially, the vignetting severely destroys the space-invariant model and induces obvious artifacts in FPM, which is the most difficult problem. The conventional method is to divide the field of view (FOV) into many tiles and omit those imperfect images, which is crude and may discards low frequency information. In this paper, we reevaluated the conditions of vignetting in FPM. Through our analysis, the maximum side length of FOV is 0.759 mm for a single full-FOV reconstruction via a 4×/0.1 NA objective and a 4 mm spacing LED array in theory, while almost 1.0 mm can be achieved in practice due to the tolerance of algorithm. We found that FPM system can treat the vignetting coefficient Vf below 0.1 as brightfield images and Vf lager than 0.9 as darkfield images, respectively. We reported an optimized distribution for designing an illuminator without vignetting effect according to the off-the-shelf commercial products, which can reconstruct full FOV in one time via a CPU. By adjusting the distribution of LED units, the system could retrieve the object with the side length of FOV up to 3.8 mm for a single full-FOV reconstruction, which achieves the largest FOV that a typical 4×/0.1 NA objective with the field number of 22 mm can afford. © 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20234515023672
• Record 5 of
  
  Title:Numerical and experimental investigations on the propagation property of a mid-infrared 7 × 1 multimode fiber combiner
  
  Author(s):He, Chunjiang(1,2); Xiao, Xusheng(1,2); Xu, Yantao(1,2); Xiao, Yang(1,2); Zhang, Hao(1,2); Guo, Haitao(1,2)
  Source: Optics Express  Volume: 31  Issue: 13  Article Number: null  DOI: 10.1364/OE.491674  Published: June 19, 2023  
  Abstract:Mid-infrared fiber combiners have great potential in power and spectral combination. However, studies on mid-infrared transmission optical field distributions using these combiners are limited. In this study, we designed and fabricated a 7 × 1 multimode fiber combiner based on sulfur-based glass fibers and observed approximately 80% per-port transmission efficiency at 4.778 µm wavelength. We investigated the propagation properties of the prepared combiners and explored the effects of transmission wavelength, output fiber length, and fusion deviation on the transmitted optical field and beam quality factor M2. Additionally, we assessed the effect of coupling on the excitation mode and spectral combination of the mid-infrared fiber combiner for multiple light sources. Our results provide an in-depth understanding of the propagation properties of the mid-infrared multimode fiber combiners, which may find applications in high-beam-quality laser devices. © 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20232814368700
• Record 6 of
  
  Title:Enhanced Adhesion of Copper Films on Fused Silica Glass Substrate by Plasma Pre-Treatment
  
  Author(s):Yang, Liqing(1); Yang, Xianli(2); Gao, Fei(1); Guan, Yongmao(1); Wan, Rui(1); Wang, Pengfei(1)
  Source: Materials  Volume: 16  Issue: 14  Article Number: 5152  DOI: 10.3390/ma16145152  Published: July 2023  
  Abstract:A non-thermal atmospheric jet plasma pre-treatment technique was introduced to help the growth of extremely sticky copper films on fused silica glass substrates. A tape test was utilized to assess the bonding quality between copper films and fused silica glass substrates. AFM was used to characterize the sample surface roughness and XPS for chemical bonding characterization. The Owens–Wendt method and a Theta Lite Optical Tensiometer were used to analyze the contact angle and surface energy. The results showed that the surface energy greatly increased from 34.6 ± 0.3 mJ·m−2 to 55.9 ± 0.4 mJ·m−2 after 25 s plasma pre-treatment due to the increasing Si-O and Si-N concentrations, which brought about the electrostatic force increasing at the copper/glass interface. After 25 s plasma pre-treatment, the average surface roughness (Sa) grew from 0.8 ± 0.1 nm to 2.4 ± 0.3 nm. With higher surface roughness, there were more spaces and vacancies for the copper atoms to make contact on the bonded surfaces and increase the mechanical bite force. The electrostatic force and the mechanical bite force on the interface helped to form an atomic diffusion connection layer and improved the interactions between the copper film and the glass substrate. The findings in the SEM supported the conclusions stated above. Therefore, the adhesion between copper films and fused silica glass substrates increased by about 20% by 25 s plasma pre-treatment compared with the untreated glass substrate. © 2023 by the authors.
  Accession Number: 20233114473893
• Record 7 of
  
  Title:Single underwater image restoration based on color correction and optimized transmission map estimation
  
  Author(s):Ke, Ke(1,2,3); Zhang, Chunmin(1,2); Wang, Yanqiang(1,2); Zhang, Yujiao(1,2); Yao, Baoli(3)
  Source: Measurement Science and Technology  Volume: 34  Issue: 5  Article Number: 055408  DOI: 10.1088/1361-6501/acb72d  Published: May 2023  
  Abstract:Underwater images often suffer from color distortion and resolution degradation due to the absorption and scattering of light. To deal with these problems, a novel underwater image restoration framework was designed to remove color deviation and background scattering successively. Firstly, an effective color correction method based on Lab color space is adopted to remove the color cast. Secondly, the color, saturation, and detail information are considered comprehensively to construct the scene depth map and edge map to estimate the transmission, and the relationship between the scattering coefficient and wavelength is used to modify the transmission map of each channel. In addition, a weighted least squares filter with adaptive smoothing parameters is introduced to estimate the local background light, which is applicable to the underwater scene with complex scattering. The experimental results show that the method performs better in color correction and detail enhancement, and the image quality is significantly improved. © 2023 IOP Publishing Ltd.
  Accession Number: 20230813622866
• Record 8 of
  
  Title:Stress-Induced Yb-Doped Large-Mode-Area Polarization-Maintaining Microstructured Fibers with Deviation of the Single-Mode Transmission Band and Delocalization of Higher-Order Modes
  
  Author(s):Ma, Yuan(1,2); Chen, Chao(1,2); Wan, Rui(1,2); Wang, Pengfei(1,2)
  Source: SSRN  Volume: null  Issue: null  Article Number: null  DOI: 10.2139/ssrn.4364068  Published: February 19, 2023  
  Abstract:The nonlinear effects and laser-induced optical and thermal damage in optical fibers, together with the limitations of beam quality and mode-field area, restrict the power scaling-up of single-mode output for developing high-power fiber lasers in the kilowatt and above range. The design of photonic crystal fibers (PCFs) with large mode areas is an effective way to address this problem. In this paper, the demands and challenges of designing very large-mode-area (VLMA-) PCFs are discussed, including the overall fiber structure design and property simulation, especially the precise definition of single-mode operating conditions of VLMA-PCFs. Finally, an advanced polarization-maintaining, Yb-doped, PCF structure with a large mode area realized by introducing both leakage channels and higher order mode-filtering units is proposed and analyzed theoretically, for which a maximum core diameter of 101 μm and single-mode field diameter of 76.33 μm at 1064 nm and a birefringence value >10-4 orders of magnitude are achieved. © 2023, The Authors. All rights reserved.
  Accession Number: 20230061424
• Record 9 of
  
  Title:Fast registration method for sequential star images
  
  Author(s):Han, Yong(1,2,3); Wen, Desheng(1); Li, Jie(2)
  Source: Applied Optics  Volume: 62  Issue: 27  Article Number: null  DOI: 10.1364/AO.495412  Published: September 20, 2023  
  Abstract:Registration of sequential star images is an important component of space observation. Especially for onboard devices, the efficiency and robustness of registration algorithms are particularly important. The typical star image registration approach based on star matching has a low tolerance for incorrect matching, and the time cost will increase rapidly as the number of stars increases. Due to the high overlap and rigid transformation of adjacent star images, a proposed method based on star angular distance (SAD) is presented. Stars are easy to locate and extract as natural feature points, and there are a large number of identical stars in adjacent star images. The rotation and translation of the SAD, composed of identical stars in adjacent star images, are the same. Therefore, maximum intersection clustering (MIC) was proposed to cluster rotation and translation, and Gaussian weight iteration (GWI) was proposed to estimate rigid transformation parameters. The use of SAD as a star image feature reduces the complexity of star image features, which can improve the efficiency of the algorithm. MIC can tolerate errors within a certain range, and GWI can lessen their impact on the results, increasing the algorithm’s robustness. Experimental results show that the proposed method can improve the trend of rapidly increasing computation as the number of stars increases and avoid the restriction that transformation parameters must be obtained with correctly matching stars. Compared to the typical triangle method and SAD similarity method, the proposed method has higher efficiency under different numbers of stars, and translation, rotation, and location errors. © 2023 Optica Publishing Group © 2023 Optica Publishing Group.
  Accession Number: 20234214906310
• Record 10 of
  
  Title:A Bioinspired Skin UV Filter with Broadband UV Protection, Photostability, and Resistance to Oxidative Damage
  
  Author(s):Li, Nini(1,2); Ji, Xiaohong(1); Mukherjee, Somnath(1); Yang, Bing(1); Ren, Yuqing(1); Wang, Changhao(1); Chen, Yashao(1)
  Source: ACS Applied Materials and Interfaces  Volume: 15  Issue: 8  Article Number: null  DOI: 10.1021/acsami.2c19773  Published: March 1, 2023  
  Abstract:In recent years, sunscreens’ adverse impacts on the environment and biology have gained wide attention. The improvement of sunscreen safety has become one of the major priorities in skin photoprotection research. It is an effective strategy to develop bionic photoprotective materials by simulating the photoprotective mechanism existing in nature. Inspired by the photoprotective mechanisms of skin and plant leaves, the bionic photoprotective material CS-SA-PDA nanosheet was developed using the free radical grafting method and Michael addition, with natural melanin analogue polydopamine (PDA) nanoparticles and plant sunscreen molecular sinapic acid (SA) as sun protection factors and natural polymer chitosan (CS) as the connecting arm. The results show that CS-SA-PDA can effectively shield UVB and UVA due to the possible synergistic effect between PDA and SA. The introduction of polymer CS significantly improved the photostability of SA and reduced the skin permeability of PDA nanoparticles. The CS-SA-PDA nanosheet can also effectively scavenge photoinduced free radicals. Furthermore, in vivo toxicity and anti-UV evaluations confirm that CS-SA-PDA has no skin irritation and is excellent against skin photodamage, which makes it an ideal skin photoprotective material. © 2023 American Chemical Society.
  Accession Number: 20230913638894
• Record 11 of
  
  Title:Influence of Graphene Stability on III-Nitride Remote Epitaxy for Exfoliation
  
  Author(s):Han, Xu(1,2); Yu, Jiadong(3); Yang, Peilong(1); Liu, Bo(1); Wang, Xun(1); Hao, Zhibiao(1,2); Luo, Yi(1,2); Sun, Changzheng(1,2); Han, Yanjun(1,2); Xiong, Bing(1,2); Wang, Jian(1,2); Li, Hongtao(1,2); Wang, Lai(1,2)
  Source: ACS Applied Nano Materials  Volume: 6  Issue: 16  Article Number: null  DOI: 10.1021/acsanm.3c02811  Published: August 25, 2023  
  Abstract:Remote epitaxy via graphene has acquired much attention because of its potential for epi-layer mechanical exfoliation. The stability of graphene during the epitaxy process is a key point in realizing epi-layer exfoliation. In this work, GaN and AlN buffer layers were grown on a graphene-coated AlN/sapphire template and studied for the stability of graphene during the different stages of III-nitrides’ remote epitaxy. The annealing experiments of graphene in different atmospheres illustrate that N2 carrier gas is the better choice to protect graphene. The graphene transition layer can remain stable during the low-temperature GaN or AlN buffer growth process, making the epi-layer exfoliable. However, when the temperature increased to a common value for GaN growth in MOCVD, recrystallization of the buffer layers happened and the graphene transition layer could be destroyed. As a result, the epi-layers cannot be exfoliated in this case. These results illustrate that the recrystallization process should be avoided or weakened to achieve exfoliation of the epi-layer. © 2023 American Chemical Society.
  Accession Number: 20233414615493
• Record 12 of
  
  Title:Demonstration of a High-Performance 3 dB Power Splitter in Silicon Nitride Loaded Lithium Niobate on Insulator
  
  Author(s):Chen, Li(1); Han, Xu(1); Zhou, Xudong(1); Yin, Ruoyu(1); Yuan, Mingrui(1); Xiao, Huifu(1); Nguyen, Thach Giang(2); Boes, Andreas(2,3,4); Ren, Guanghui(2); Mitchell, Arnan(2); Tian, Yonghui(1,5)
  Source: Laser and Photonics Reviews  Volume: 17  Issue: 11  Article Number: 2300377  DOI: 10.1002/lpor.202300377  Published: November 2023  
  Abstract:Lithium niobate on insulator (LNOI) has emerged as a promising platform for photonic integrated circuits (PICs) due to the excellent electro-optic (EO) properties of lithium niobate (LN). However, such a platform still lacks many critical passive components with superior performance for constructing PICs. The 3 dB power splitters are one of the important passive components in PICs for separating and combining optical energy to construct the other crucial photonic devices such as Mach–Zehnder modulators, optical switches, and optical phased arrays, et al. In this contribution, an ultra-broadband and compact 3 dB power splitter is proposed and demonstrated using a tapered subwavelength grating (SWG)-assisted Y-branch on a silicon nitride (Si3N4) loaded LNOI platform. The SWG is used to alleviate fabrication challenges and reduce radiation loss while increasing the evanescent coupling. The simulation result shows an excellent operation bandwidth of 800 nm (from 1.2 to 2.0 µm) at the insertion loss (IL) of 0.12 dB. The proposed device with a compact footprint (9.6 × 3 µm2) is finally fabricated on a Si3N4 loaded LNOI platform, and the experimental result shows the IL of © 2023 Wiley-VCH GmbH.
  Accession Number: 20233714729417