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Residual stress modeling of mitigated fused silica damage sites with CO_(2)laser annealing

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Chinese Physics B 2024年第3期33卷 509-514页

作者：张传超廖威张丽娟蒋晓龙方振华蒋晓东 laser Fusion research center China Academy of Engineering PhysicsMianyang 621900China

A numerical model based on measured fictive temperature distributions is explored to evaluate the residual stress fields of CO_(2)laser-annealed mitigated fused silica damage *** proposed model extracts the residual strain from the differences in thermoelastic contraction of fused silica with different fictive temperatures from the initial frozen-in temperatures to ambient *** residual stress fields of mitigated damage sites for the CO_(2)laser-annealed case are obtained by a finite element analysis of equilibrium equations and constitutive *** simulated results indicate that the proposed model can accurately evaluate the residual stress fields of laser-annealed mitigated damage sites with a complex thermal *** calculated maximum hoop stress is in good agreement with the reported experimental *** estimated optical retardance profiles from the calculated radial and hoop stress fields are consistent with the photoelastic *** results provide sufficient evidence to demonstrate the suitability of the proposed model for describing the residual stresses of mitigated fused silica damage sites after CO_(2)laser annealing.

关键词： fused silica damage mitigation residual stress laser annealing

Continuous gradient fusion class activation mapping: segmentation of laser-induced damage on large-aperture optics in dark-field images

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High Power laser science and Engineering 2024年第1期12卷 30-41页

作者： Yueyue Han Yingyan Huang Hangcheng Dong Fengdong Chen Fa Zeng Zhitao Peng Qihua Zhu Guodong Liu School of Instrumentation science and Engineering Harbin Institute of TechnologyHarbinChina research center of laser Fusion China Academy of Engineering PhysicsMianyangChina

Segmenting dark-field images of laser-induced damage on large-aperture optics in high-power laser facilities is challenged by complicated damage morphology, uneven illumination and stray light interference. Fully supervised semantic segmentation algorithms have achieved state-of-the-art performance but rely on a large number of pixel-level labels, which are time-consuming and labor-consuming to produce. LayerCAM, an advanced weakly supervised semantic segmentation algorithm, can generate pixel-accurate results using only image-level labels, but its scattered and partially underactivated class activation regions degrade segmentation performance. In this paper, we propose a weakly supervised semantic segmentation method, continuous gradient class activation mapping(CAM) and its nonlinear multiscale fusion(continuous gradient fusion CAM). The method redesigns backpropagating gradients and nonlinearly activates multiscale fused heatmaps to generate more fine-grained class activation maps with an appropriate activation degree for different damage site sizes. Experiments on our dataset show that the proposed method can achieve segmentation performance comparable to that of fully supervised algorithms.

关键词： class activation maps laser-induced damage semantic segmentation weakly supervised learning

The modeling non-sequential double ionization of helium atom under highintensity femtosecond laser pulses with shielding charge approximation

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Communications in Theoretical Physics 2024年第2期76卷 151-156页

作者： Marjan Zakavi Mohammad Sabaeian Department of Physics Faculty of ScienceShahid Chamran University of AhvazIran center for research on laser and Plasma Shahid Chamran University of AhvazIran

In this study,we successfully extracted the‘knee structure’for non-sequential double ionization(NSDI)in the helium *** achieve this,for the first time,we solved the time-dependent Schrödinger equation in three dimensions for the helium atom,utilizing the shielding charge *** findings corroborate prior observations by Wang et al[Wang and Eberly,***.105,083001(2010)],demonstrating that NSDI occurs within a narrower time window in circular polarization compared to linear *** a result,the yield of linear polarization was higher than that of circular polarization,aligning with the previously reported ***,in the case of circular polarization,the time window further narrows with increasing intensity,attributed to a decrease in the time-of-flight.

关键词： NSDI knee structure TDSE shielding charge helium 3D-TDSE

Additive manufacturing of NiTi lightweight porous structures bio-mimicking coral skeleton with enhanced mechanical properties and shape memory functions

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science China Technological sciences 2024年第8期67卷 2461-2474页

作者： LIU Xin GU DongDong YUAN LuHao ZHANG Han SUN JianFeng CHEN WenXin WANG Jie SHI KeYu Jiangsu Provincial research center for laser Additive Manufacturing of High-Performance Components College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics

Concerning the high demand for lightweight and multifunctional properties of engineering structures, the coral skeleton-inspired sheet-based（CSS） structure, which was a novel bio-mimicking coral skeleton wall-septa architecture with a unique ability to resist wave shocks was fabricated using NiTi alloy by laser powder bed fusion（LPBF） technology. The effects of laser energy density（LED） on surface morphologies, microstructures, phase transformation behavior, and mechanical properties of LPBFfabricated CSS structures were systematically investigated. The results indicated that the size deviation was predominantly governed by powder adhesion and step effect. NiTi CSS structures with LED of 71 J·mm-3possessed superior compressive modulus（～400 MPa）, ultimate strength（～13 MPa）, and energy absorption efficiency（～69%）. The compression fracture mechanism of the LPBF-fabricated NiTi CSS structures was revealed to be predominantly brittle fracture accompanied by ductile fracture. Furthermore, the Ni4Ti3nanoprecipitates induced the precipitation strengthening effect, enabling better shape memory response at LED of 71 J·mm-3, with a recoverable strain of 3.63% and recovery ratio of 90.8%, after heating under a pre-strain of 4%. This study highlights the importance of a bionic design strategy for enhancing the mechanical properties of NiTi components and offers the possibility to tailor its functional properties.

关键词： bioinspired structures laser powder bed fusion NiTi shape memory alloy mechanical performance

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Non-blind super-resolution reconstruction for laser-induced damage dark-field imaging of optical elements

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Chinese optics Letters 2024年第4期22卷 36-41页

作者：王倩陈凤东韩越越曾发路程刘国栋 Instrument science and Technology Harbin Institute of TechnologyHarbin 150001China research center of laser Fusion China Academy of Engineering PhysicsMianyang 621900China

The laser-induced damage detection images used in high-power laser facilities have a dark background,few textures with sparse and small-sized damage sites,and slight degradation caused by slight defocus and optical diffraction,which make the image superresolution(SR)reconstruction *** propose a non-blind SR reconstruction method by using an exquisite mixing of high-,intermediate-,and low-frequency information at each stage of pixel reconstruction based on *** simplify the channel attention mechanism and activation function to focus on the useful channels and keep the global information in the *** pay more attention on the damage area in the loss function of our end-toend deep neural *** constructing a high-low resolution image pairs data set,we precisely measure the point spread function(PSF)of a low-resolution imaging system by using a Bernoulli calibration pattern;the influence of different distance and lateral position on PSFs is also considered.A high-resolution camera is used to acquire the ground-truth images,which is used to create a low-resolution image pairs data set by convolving with the measured *** on the data set,our network has achieved better results,which proves the effectiveness of our method.

关键词： laser-induced damage image superresolution image segmentation

Influence of Nd^(3+) concentration on mid-infrared emission in PbF_(2) crystal co-doped with Ho^(3+) and Nd^(3+) ions

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Journal of Rare Earths 2024年第3期42卷 479-487,I0002页

作者： Yan Chen Juncheng Tan Peixiong Zhang Weibi Zheng Lin Li Lianhan Zhang Zhen Li Yin Hang Zhenqiang Chen Department of Optoelectronic Engineering Jinan UniversityGuangzhou510632China Guangdong Provincial Engineering research centerof Crystal and laser Technology.Guangzhou 510632China research center of laser Crystal Key Laboratory of High Power Laser MaterialsShanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai201800China

A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 μm)fluorescence emissions of Ho^(3+)ions in the PbF_(2) crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd^(3+)ions and Ho~(3+)ions under different concentrations of the Nd^(3+)ions was systematically analyzed. The results show that the Nd^(3+)ions have good sensitization and deactivation effect on the Ho^(3+)ions to stimulate the mid-infrared fluorescence emissions. The experimental analysis proves that the sensitization efficiency of the Nd^(3+)ions is relatively stable at around 93.45% with varying Nd^(3+)-doping concentrations. Concentration dependence studies indicate that the concentration of the Nd^(3+)ions has significant influence on mid-infrared *** the doping concentration of the Nd^(3+)ions is up to 2.0 at%, the intensity of ~2.0, ~2.9 and ~3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd^(3+)-doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho_(0.02)Nd_(0.02)Pb_(0.96)F_(2) crystal displays the best performance. All the results show that the Nd^(3+)/Ho^(3+)co-doped PbF_(2) crystals might act as a useful optical medium for mid-infrared laser applications.

关键词： Crystal growth Mid-infrared PbF_(2) Rare earth ions

Electrically tunable phase-change metasurface for dynamic infrared thermal camouflage

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Photonics research 2024年第2期12卷 292-300页

作者： YUFENG XIONG YUNZHENG WANG CHAO FENG YAOLAN TIAN LIANG GAO JUN-LEI WANG ZHUANG ZHUO XIAN ZHAO center for optics research and Engineering Key Laboratory of Laser&Infrared SystemMinistry of EducationShandong UniversityQingdao 266237China School of Information science and Engineering Shandong UniversityQingdao 266237China

Dynamic infrared thermal camouflage technology has attracted extensive attention due to its ability to thermally conceal targets in various environmental backgrounds by tuning thermal *** use of phase change materials(PCMs)offers numerous advantages,including zero static power,rapid modulation rate,and large emissivity tuning ***,existing PCM solutions still encounter several practical application challenges,such as temperature uniformity,amorphization achievement,and adaptability to different *** this paper,we present the design of an electrically controlled metal-insulator-metal thermal emitter based on a PCM metasurface,and numerically investigate its emissivity tunability,physical mechanisms,heat conduction,and thermal camouflage performance across different ***,the influence of the quench rate on amorphization was studied to provide a guidance for evaluating and optimizing device *** results reveal that the thermal emitter exhibits a wide spectral emissivity tuning range between 8 and 14μm,considerable quench rates for achieving amorphization,and the ability to provide thermal camouflage across a wide background temperature ***,it is anticipated that this contribution will promote the development of PCM-based thermal emitters for practical dynamic infrared thermal camouflage technology with broad applications in both civilian and military domains.

关键词： thermal dynamic phase

Microscopic nonlinear optical activities and ultrafast carrier dynamics in layered AgInP_(2)S_(6)

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Photonics research 2024年第4期12卷 691-700页

作者： ZIXIN WANG NINGNING DONG YU MAO CHENDUAN CHEN XIN CHEN CHANG XU ZHOUYUAN YAN JUN WANG Aerospace laser Technology and Systems Department CAS Key Laboratory of Materials for High-Power LaserShanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China center of Materials science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China CAS center for Excellence in Ultra-intense laser science(CEULS) State Key Laboratory of High Field Laser PhysicsShanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China

Since the emergence of graphene, transition metal dichalcogenides, and black phosphorus, two-dimensional materials have attracted significant attention and have driven the development of fundamental physics and optoelectronic devices. Metal phosphorus trichalcogenides(MPX3), due to their large bandgap of 1.3–3.5 eV, enable the extension of optoelectronic applications to visible and ultraviolet(UV) wavelengths.

关键词： nonlinear ultraviolet phosphorus

A highly sensitive LITES sensor based on a multi-pass cell with dense spot pattern and a novel quartz tuning fork with low frequency

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Opto-Electronic Advances 2024年第3期7卷 26-34页

作者： Yahui Liu Shunda Qiao Chao Fang Ying He Haiyue Sun Jian Liu Yufei Ma National Key Laboratory of science and Technology on Tunable laser Harbin Institute of TechnologyHarbin 150000China Zhengzhou research Institute Harbin Institute of TechnologyZhengzhou 450000China Advanced Microscopy and Instrumentation research center School of Instrumentation Science and EngineeringHarbin Institute of TechnologyHarbin 150080China.

A highly sensitive light-induced thermoelectric spectroscopy(LITES)sensor based on a multi-pass cell(MPC)with dense spot pattern and a novel quartz tuning fork(QTF)with low resonance frequency is reported in this *** erbi-um-doped fiber amplifier(EDFA)was employed to amplify the output optical power so that the signal level was further *** optical path length(OPL)and the ratio of optical path length to volume(RLV)of the MPC is 37.7 m and 13.8 cm^(-2),respectively.A commercial QTF and a self-designed trapezoidal-tip QTF with low frequency of 9461.83 Hz were used as the detectors of the sensor,*** target gas selected to test the performance of the system was acetylene(C2H2).When the optical power was constant at 1000 mW,the minimum detection limit(MDL)of the C2H2-LITES sensor can be achieved 48.3 ppb when using the commercial QTF and 24.6 ppb when using the trapezoid-al-tip *** improvement of the detection performance by a factor of 1.96 was achieved after replacing the commer-cial QTF with the trapezoidal-tip QTF.

关键词： light-induced thermoelectric spectroscopy quartz tuning fork multi-pass cell gas sensing