Pub Date : 2024-10-12DOI: 10.1016/j.optlastec.2024.111947
Wensheng Zhang , Linjun Li , Hong Liang
We present a high-efficiency continuous-wave and LGS electro-optically Q-switched Tm:LuAG laser for the first time in this paper. The in-band pumping structure was realized by using a MgO:PPLN optical parametric oscillator at 1623 nm as the pump source. Under high-efficiency CW regime, a maximum output power of 10.8 W at 2023 nm was obtained under an incident pump power of 19.2 W, corresponding to a slope efficiency of 60.5 % and an optical-to-optical efficiency of 56.3 %. In addition, with 90/10 knife-edge method, the M2-factors in the x- and y-directions were measured to be about 1.3 and 1.2 at maximum output power, respectively. Under the EO Q-switching regime, a maximum average output power of 5.62 W was achieved under an incident pump power of 19.2 W and a repetition rate of 3000 Hz, corresponding to a slope efficiency of 34.2 %. With a repetition rate of 500 Hz, a maximum pulse energy of 8.14 mJ and a minimum pulse width of 32 ns were achieved with an incident pump power of 19.2 W, corresponding to a maximum calculated peak power of 254 kW.
{"title":"High-efficiency continuous-wave and LGS electro-optically Q-switched Tm: LuAG laser in-band pumped at 1623 nm","authors":"Wensheng Zhang , Linjun Li , Hong Liang","doi":"10.1016/j.optlastec.2024.111947","DOIUrl":"10.1016/j.optlastec.2024.111947","url":null,"abstract":"<div><div>We present a high-efficiency continuous-wave and LGS electro-optically Q-switched Tm:LuAG laser for the first time in this paper. The in-band pumping structure was realized by using a MgO:PPLN optical parametric oscillator at 1623 nm as the pump source. Under high-efficiency CW regime, a maximum output power of 10.8 W at 2023 nm was obtained under an incident pump power of 19.2 W, corresponding to a slope efficiency of 60.5 % and an optical-to-optical efficiency of 56.3 %. In addition, with 90/10 knife-edge method, the M<sup>2</sup>-factors in the x- and y-directions were measured to be about 1.3 and 1.2 at maximum output power, respectively. Under the EO Q-switching regime, a maximum average output power of 5.62 W was achieved under an incident pump power of 19.2 W and a repetition rate of 3000 Hz, corresponding to a slope efficiency of 34.2 %. With a repetition rate of 500 Hz, a maximum pulse energy of 8.14 mJ and a minimum pulse width of 32 ns were achieved with an incident pump power of 19.2 W, corresponding to a maximum calculated peak power of 254 kW.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111947"},"PeriodicalIF":4.6,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111953
Mohamad Sadegh Pishvaei, Mohamad Hasan Yavari
A high-performance graphene electro-refractive and electro-absorption optical micro-ring modulator is investigated. Various graphene strip and slot waveguides are studied for their potential to enhance modulation efficiency due to the unique properties of graphene, such as its exceptional optical and electrical characteristics. The bandwidth (BW) of the presented ring modulator in critical coupling conditions is enhanced by optimizing active region length and oxide thickness. According to the simulation results, a double layer graphene ring modulator (DLG-RM) based on a slot waveguide exhibits superior modulation efficiency, with an extinction ratio (ER) of more than 60 dB, an electro-optic bandwidth of more than 40 GHz, and power consumption of less than 40 fJ/bit for phase as well as amplitude modulation at around 1550 nm. For efficient coupling between the strip and the slot waveguide, an optimized symmetric multi-mode interferometer (MMI) is implied. By proper design of DLG-RM, the vital tradeoff between ER and BW is enhanced, and a device with a small footprint and CMOS compatibility is proposed for optical interconnects.
{"title":"Design and analysis of graphene slot waveguide micro-ring modulator with high extinction ratio and bandwidth","authors":"Mohamad Sadegh Pishvaei, Mohamad Hasan Yavari","doi":"10.1016/j.optlastec.2024.111953","DOIUrl":"10.1016/j.optlastec.2024.111953","url":null,"abstract":"<div><div>A high-performance graphene electro-refractive and electro-absorption optical micro-ring modulator is investigated. Various graphene strip and slot waveguides are studied for their potential to enhance modulation efficiency due to the unique properties of graphene, such as its exceptional optical and electrical characteristics. The bandwidth (BW) of the presented ring modulator in critical coupling conditions is enhanced by optimizing active region length and oxide thickness. According to the simulation results, a double layer graphene ring modulator (DLG-RM) based on a slot waveguide exhibits superior modulation efficiency, with an extinction ratio (ER) of more than 60 dB, an electro-optic bandwidth of more than 40 GHz, and power consumption of less than 40 fJ/bit for phase as well as amplitude modulation at around 1550 nm. For efficient coupling between the strip and the slot waveguide, an optimized symmetric multi-mode interferometer (MMI) is implied. By proper design of DLG-RM, the vital tradeoff between ER and BW is enhanced, and a device with a small footprint and CMOS compatibility is proposed for optical interconnects.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111953"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111874
Qi Liu , Ju Huo , Xiyu Tang , Muyao Xue
To address the limited field of view (FOV) of CMOS grayscale cameras, complex lighting conditions, and the scarcity of image features in industrial applications, a novel image stitching method is proposed for CMOS grayscale cameras operating under varying lighting conditions. This method broadens the camera’s FOV while preserving the interpretability of image features, thereby enhancing the robustness and generalizability of image stitching across diverse lighting environments and feature-sparse settings. In the feature extraction phase, a hybrid deep feature extraction network is designed. By employing a deep learning-based approach, the network ensures the extraction of a substantial quantity of features. Building on this foundation, a method for line feature selection and reconstruction is developed to refine feature-matching accuracy, which increases the number of matching lines in extreme lighting and feature-scarce situations, and enriches the image features for subsequent stitching processes. In the subsequent image transformation phase, planar feature constraints are introduced; matching feature points and lines are used to generate planar features, addressing alterations in the collective shape of planes that are common in industrial image stitching. The paper concludes by presenting quantitative evaluation metrics for planar feature-based stitching. Experimental results validate the effectiveness and feasibility of the proposed method for image stitching of CMOS grayscale cameras under varied lighting conditions and in feature-deficient industrial settings, offering a viable solution to the challenges posed by the limited imaging FOV in industrial applications.
{"title":"Image stitching method for CMOS grayscale cameras in industrial applications","authors":"Qi Liu , Ju Huo , Xiyu Tang , Muyao Xue","doi":"10.1016/j.optlastec.2024.111874","DOIUrl":"10.1016/j.optlastec.2024.111874","url":null,"abstract":"<div><div>To address the limited field of view (FOV) of CMOS grayscale cameras, complex lighting conditions, and the scarcity of image features in industrial applications, a novel image stitching method is proposed for CMOS grayscale cameras operating under varying lighting conditions. This method broadens the camera’s FOV while preserving the interpretability of image features, thereby enhancing the robustness and generalizability of image stitching across diverse lighting environments and feature-sparse settings. In the feature extraction phase, a hybrid deep feature extraction network is designed. By employing a deep learning-based approach, the network ensures the extraction of a substantial quantity of features. Building on this foundation, a method for line feature selection and reconstruction is developed to refine feature-matching accuracy, which increases the number of matching lines in extreme lighting and feature-scarce situations, and enriches the image features for subsequent stitching processes. In the subsequent image transformation phase, planar feature constraints are introduced; matching feature points and lines are used to generate planar features, addressing alterations in the collective shape of planes that are common in industrial image stitching. The paper concludes by presenting quantitative evaluation metrics for planar feature-based stitching. Experimental results validate the effectiveness and feasibility of the proposed method for image stitching of CMOS grayscale cameras under varied lighting conditions and in feature-deficient industrial settings, offering a viable solution to the challenges posed by the limited imaging FOV in industrial applications.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111874"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111934
Benjamin Dwir
InGaAs/GaAs quantum dots (QDs) embedded in a GaAs substrate are very useful photon sources, including single and entangled photons, due to their unperturbed environment. Contrary to self-formed QDs, those grown in pyramidal pits can be well controlled in position and energy, important properties for scaling. However, photon extraction efficiency from these QDs is limited due to the GaAs/Air index mismatch and non-directionality of the emission. GaAs nanowires grown vertically on top of these QDs can serve as resonant antennas, thus enhancing their emission and increasing their usefulness as sources. Such structures were fabricated and their photon emission was studied by micro-photoluminescence as function of excitation power and temperature. The structures showed an intensity increase by up to x36 over quantum dots without nanowire antennas.
{"title":"Enhanced photon emission from site- and energy-controlled InGaAs/GaAs quantum dots coupled to GaAs nanowires","authors":"Benjamin Dwir","doi":"10.1016/j.optlastec.2024.111934","DOIUrl":"10.1016/j.optlastec.2024.111934","url":null,"abstract":"<div><div>InGaAs/GaAs quantum dots (QDs) embedded in a GaAs substrate are very useful photon sources, including single and entangled photons, due to their unperturbed environment. Contrary to self-formed QDs, those grown in pyramidal pits can be well controlled in position and energy, important properties for scaling. However, photon extraction efficiency from these QDs is limited due to the GaAs/Air index mismatch and non-directionality of the emission. GaAs nanowires grown vertically on top of these QDs can serve as resonant antennas, thus enhancing their emission and increasing their usefulness as sources. Such structures were fabricated and their photon emission was studied by micro-photoluminescence as function of excitation power and temperature. The structures showed an intensity increase by up to x36 over quantum dots without nanowire antennas.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111934"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111925
Xuan Yu, Chao Wei, Sheng Liu, Cheng Lei, Du Wang
Polymer terahertz (THz) fibers have attracted significant interest due to their compactness and capability in efficient terahertz transmission and gas sensing. The urgent demand for the development of polymer THz fibers lies in the fabrication methods that are compatible with flexible designs, enabling low-loss waveguides. This paper presents a comprehensive investigation into the numerical and experimental aspects of the one-step extrusion process, offering a viable solution for fabricating flexible and low-loss THz waveguides. Precise shaping of the proposed structures is achieved through the choice of COC polymer, moderate flow rate Qm and mold temperature TMOLD. Excessive Qm or TMOLD leads to partial or complete collapse of the polymer waveguide while insufficient Qm or TMOLD is not conducive to a smooth extrusion process. The fabricated waveguide shows an average loss of 3 dB/m over a frequency range from 1.0 to 2.0 THz. The feasibility and practicality of the one-step extrusion establish its potential for further advancements in polymer fiber fabrication.
{"title":"Process analysis of COC terahertz fiber fabrication by one-step extrusion","authors":"Xuan Yu, Chao Wei, Sheng Liu, Cheng Lei, Du Wang","doi":"10.1016/j.optlastec.2024.111925","DOIUrl":"10.1016/j.optlastec.2024.111925","url":null,"abstract":"<div><div>Polymer terahertz (THz) fibers have attracted significant interest due to their compactness and capability in efficient terahertz transmission and gas sensing. The urgent demand for the development of polymer THz fibers lies in the fabrication methods that are compatible with flexible designs, enabling low-loss waveguides. This paper presents a comprehensive investigation into the numerical and experimental aspects of the one-step extrusion process, offering a viable solution for fabricating flexible and low-loss THz waveguides. Precise shaping of the proposed structures is achieved through the choice of COC polymer, moderate flow rate <em>Q</em><sub>m</sub> and mold temperature <em>T</em><sub>MOLD</sub>. Excessive <em>Q</em><sub>m</sub> or <em>T</em><sub>MOLD</sub> leads to partial or complete collapse of the polymer waveguide while insufficient <em>Q</em><sub>m</sub> or <em>T</em><sub>MOLD</sub> is not conducive to a smooth extrusion process. The fabricated waveguide shows an average loss of 3 dB/m over a frequency range from 1.0 to 2.0 THz. The feasibility and practicality of the one-step extrusion establish its potential for further advancements in polymer fiber fabrication.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111925"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111955
Lei Gao, Chang Liu, Junjie Liu, Kejiao Wang
The thermal protection components prepared by SiC/SiC composites require laser processing of a large number of high-quality cooling holes. Improving the quality of femtosecond laser drilling for SiC/SiC composites using field-assisted techniques is an unexplored area. This study aims to bridge this research gap by evaluating and comparing femtosecond laser drilling performance in SiC/SiC composites under varied environments (unassisted, magnetic-assisted, water-assisted, and water/magnetic-assisted). The investigation delves into the effects of magnetic and water assistance on hole geometric properties, elucidating processing mechanisms. In addition, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used to analyze microscopic characteristics. The results show that water-assisted increases the hole diameter more significantly compared to magnetic-assisted. It is worth noting that water-assisted improves the roundness of the entrance and exit, while magnetic-assisted affects the roundness of the entrance. Water-assisted oxidation inhibition and water flow-promoted debris removal effectively mitigated oxide deposition and diffusion, resulting in improved morphology of the entrance/exit and cross-section. Importantly, water/magnetic-assisted drilling significantly improved the hole wall morphology and reduced the surface roughness by 93.3%. EDS and XPS analyses showed that magnetic-assisted and water-assisted inhibited oxidation in the deposition and diffusion zones at the entrance, while magnetic-assisted performed better in inhibiting oxidation in the diffusion zone. Water/magnetic-assisted drilling is an effective method to improve the quality of femtosecond laser drilling of SiC/SiC composites. This study provides new insight for future high-quality drilling of ceramic matrix reinforced composites.
{"title":"Femtosecond laser drilling of SiC/SiC composites in longitudinal magnetic field and semi-water immersion assistance","authors":"Lei Gao, Chang Liu, Junjie Liu, Kejiao Wang","doi":"10.1016/j.optlastec.2024.111955","DOIUrl":"10.1016/j.optlastec.2024.111955","url":null,"abstract":"<div><div>The thermal protection components prepared by SiC/SiC composites require laser processing of a large number of high-quality cooling holes. Improving the quality of femtosecond laser drilling for SiC/SiC composites using field-assisted techniques is an unexplored area. This study aims to bridge this research gap by evaluating and comparing femtosecond laser drilling performance in SiC/SiC composites under varied environments (unassisted, magnetic-assisted, water-assisted, and water/magnetic-assisted). The investigation delves into the effects of magnetic and water assistance on hole geometric properties, elucidating processing mechanisms. In addition, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used to analyze microscopic characteristics. The results show that water-assisted increases the hole diameter more significantly compared to magnetic-assisted. It is worth noting that water-assisted improves the roundness of the entrance and exit, while magnetic-assisted affects the roundness of the entrance. Water-assisted oxidation inhibition and water flow-promoted debris removal effectively mitigated oxide deposition and diffusion, resulting in improved morphology of the entrance/exit and cross-section. Importantly, water/magnetic-assisted drilling significantly improved the hole wall morphology and reduced the surface roughness by 93.3%. EDS and XPS analyses showed that magnetic-assisted and water-assisted inhibited oxidation in the deposition and diffusion zones at the entrance, while magnetic-assisted performed better in inhibiting oxidation in the diffusion zone. Water/magnetic-assisted drilling is an effective method to improve the quality of femtosecond laser drilling of SiC/SiC composites. This study provides new insight for future high-quality drilling of ceramic matrix reinforced composites.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111955"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111865
Ruyi Han , Shenghai Liao , Shujun Fu , Xingzhou Wang
Low-rank prior has important applications in image restoration tasks, particularly in filling in missing information through low-rank matrix completion models. Although the truncated nuclear norm is a classic low-rank algorithm, practical solutions often rely on convex regularized nuclear norm to approximate the rank function, which limits its approximation ability and leads to blurry edges and loss of details. To improve restoration performance, we introduce a non-convex -norm. Theoretical analysis shows that the -norm approximates the rank function more accurately than the nuclear norm, leading to a novel non-convex low-rank approximation model. Furthermore, we enhance the model by introducing transform domain sparse regularization, aimed at capturing more local details and texture information, thereby improving inpainting quality. Addressing the limitations of traditional low-rank matrix restoration models in cases of entire row or column missing, we introduce a multi-pixel window strategy based on the new model, utilizing non-local similarity to search for similar blocks in the multi-pixel neighborhood of the target block to restore the entire column and eliminate residual column artifacts. Our method demonstrates excellent performance. We compare it with several state-of-the-art image restoration techniques across multiple tasks, including pixel restoration, text and scratch removal, column inpainting, and cloud removal. Experimental results prove that our method shows significant advantages in both visual quality and quantitative evaluation.
{"title":"Transformed sparsity-boosted low-rank model for image inpainting with non-convex γ-norm regularization and non-local prior","authors":"Ruyi Han , Shenghai Liao , Shujun Fu , Xingzhou Wang","doi":"10.1016/j.optlastec.2024.111865","DOIUrl":"10.1016/j.optlastec.2024.111865","url":null,"abstract":"<div><div>Low-rank prior has important applications in image restoration tasks, particularly in filling in missing information through low-rank matrix completion models. Although the truncated nuclear norm is a classic low-rank algorithm, practical solutions often rely on convex regularized nuclear norm to approximate the rank function, which limits its approximation ability and leads to blurry edges and loss of details. To improve restoration performance, we introduce a non-convex <span><math><mi>γ</mi></math></span>-norm. Theoretical analysis shows that the <span><math><mi>γ</mi></math></span>-norm approximates the rank function more accurately than the nuclear norm, leading to a novel non-convex low-rank approximation model. Furthermore, we enhance the model by introducing transform domain sparse regularization, aimed at capturing more local details and texture information, thereby improving inpainting quality. Addressing the limitations of traditional low-rank matrix restoration models in cases of entire row or column missing, we introduce a multi-pixel window strategy based on the new model, utilizing non-local similarity to search for similar blocks in the multi-pixel neighborhood of the target block to restore the entire column and eliminate residual column artifacts. Our method demonstrates excellent performance. We compare it with several state-of-the-art image restoration techniques across multiple tasks, including pixel restoration, text and scratch removal, column inpainting, and cloud removal. Experimental results prove that our method shows significant advantages in both visual quality and quantitative evaluation.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111865"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.optlastec.2024.111916
Daniel Franta , Mihai-George Mureșan , Pavel Ondračka , Beáta Hroncová , František Vižďa
Terbium gallium garnet (TGG – ) single crystal was optically characterized using the multi-sample and multi-instrument method across a wide spectral range with the help of the universal dispersion model. The obtained optical constants cover the spectral range from the far-IR region () to the vacuum-UV region (10.3 eV). The applied dispersion model includes all elementary absorption processes occurring within the spectral range that affect the dielectric response, including phonons and valence electron excitations. The primary objective was to accurately determine the optical constants with the highest possible precision. The optical results were compared with ab initio density functional theory calculations to gain insight into the nature of the absorption edge and the distribution of the f-electron excitations.
在通用色散模型的帮助下，使用多样品和多仪器方法对铽镓石榴石（TGG - Tb3Ga5O12）单晶进行了宽光谱范围的光学表征。所获得的光学常数覆盖了从远红外区（25 厘米-1）到真空紫外区（10.3 电子伏特）的光谱范围。应用的色散模型包括光谱范围内发生的影响介电响应的所有基本吸收过程，包括声子和价电子激发。主要目标是以尽可能高的精度精确测定光学常数。光学结果与原子序数密度泛函理论计算结果进行了比较，以深入了解吸收边缘的性质和 f 电子激发的分布。
{"title":"Wide spectral range optical characterization of terbium gallium garnet (TGG) single crystal by universal dispersion model","authors":"Daniel Franta , Mihai-George Mureșan , Pavel Ondračka , Beáta Hroncová , František Vižďa","doi":"10.1016/j.optlastec.2024.111916","DOIUrl":"10.1016/j.optlastec.2024.111916","url":null,"abstract":"<div><div>Terbium gallium garnet (TGG – <span><math><mrow><msub><mrow><mi>Tb</mi></mrow><mrow><mn>3</mn></mrow></msub><msub><mrow><mi>Ga</mi></mrow><mrow><mn>5</mn></mrow></msub><msub><mrow><mi>O</mi></mrow><mrow><mn>12</mn></mrow></msub></mrow></math></span>) single crystal was optically characterized using the multi-sample and multi-instrument method across a wide spectral range with the help of the universal dispersion model. The obtained optical constants cover the spectral range from the far-IR region (<span><math><mrow><mn>25</mn><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>) to the vacuum-UV region (10.3<!--> <!-->eV). The applied dispersion model includes all elementary absorption processes occurring within the spectral range that affect the dielectric response, including phonons and valence electron excitations. The primary objective was to accurately determine the optical constants with the highest possible precision. The optical results were compared with <em>ab initio</em> density functional theory calculations to gain insight into the nature of the absorption edge and the distribution of the f-electron excitations.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111916"},"PeriodicalIF":4.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
1030-nm 320-fs-laser pulses were used to irradiate surface of Ti6Al4V titanium alloy in air and water environments. Laser-induced periodic surface structures (LIPSS) were produced at variable laser fluence F0 = 0.08–1.2 J/cm2 and accompanying changes in topography and elemental/phase composition were studied by SEM, TEM, AFM, and XRD. After high-fluence laser texturing in air, resulting in rough micro-protrusions covered by LIPSS and TiO layer, the microhardness was improved by 25 % and residual tensile stresses detected at a depth of 2.3 μm beneath the structure, reached 150 MPa. Compressive stresses induced by laser texturing at F0 ≤ 0.4 J/cm2 in air were shown to have a minimal effect on fatigue life.
{"title":"Effect of LIPSS formation on structure and properties of Ti6Al4V titanium alloy","authors":"E.V. Golosov , M.V. Zhidkov , N.A. Smirnov , O.A. Golosova , S.I. Kudryashov","doi":"10.1016/j.optlastec.2024.111931","DOIUrl":"10.1016/j.optlastec.2024.111931","url":null,"abstract":"<div><div>1030-nm 320-fs-laser pulses were used to irradiate surface of Ti6Al4V titanium alloy in air and water environments. Laser-induced periodic surface structures (LIPSS) were produced at variable laser fluence <em>F</em><sub>0</sub> = 0.08–1.2 J/cm<sup>2</sup> and accompanying changes in topography and elemental/phase composition were studied by SEM, TEM, AFM, and XRD. After high-fluence laser texturing in air, resulting in rough micro-protrusions covered by LIPSS and TiO layer, the microhardness was improved by 25 % and residual tensile stresses detected at a depth of 2.3 μm beneath the structure, reached 150 MPa. Compressive stresses induced by laser texturing at <em>F</em><sub>0</sub> ≤ 0.4 J/cm<sup>2</sup> in air were shown to have a minimal effect on fatigue life.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111931"},"PeriodicalIF":4.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.optlastec.2024.111860
Jiachong Guo , Xing Liu , Weiguo Liu , Angang Luo , Xinlu Si
In this study, to address the issues of short rendezvous time between the projectile and target as well as the weak target acquisition capability under high-speed rendezvous conditions, a new forward-looking dual-linear array rotational scanning laser fuze based on linear array laser detectors is proposed. The working principle of this fuze is discussed, according to which the parameters such as the maximum adjacent beam angle, maximum adjacent pulsed beam angle, and minimum pulse frequency are derived. Considering the spatiotemporal rendezvous relationship between the “cylindrical” target and the scanning light field, a multi-line laser scanning target size calculation model is established to determine the contour features of the target. Additionally, a multi-feature information fusion method is proposed, enabling the classification and recognition of targets of different sizes. To mitigate laser signal interference from pseudo-pulse signals, a time window denoising filtering method is adopted based on the characteristics of the multi-line laser target echo signal. In addition, the impact of different combinations of fusion features, the number of fused frames, and detection frequency on the recognition performance is analyzed. The experimental and simulation results show that the proposed forward-looking dual-linear array rotational scanning laser fuze effectively extends the duration of scanning rendezvous and captures more frames of target information. Moreover, integrating target contour features significantly enhances the recognition capability for targets of different sizes. Additionally, the introduction of target contour features can significantly improve the recognition capability for targets with different sizes.
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