Optics and Laser Technology最新文献

{"title":"Performance analysis of MIMO FSO adaptive mode switching in Malaga turbulent channels with pointing error","authors":"Dan Chen ,&nbsp;Linhai Tang ,&nbsp;Mingjun Wang ,&nbsp;Yuan Liu","doi":"10.1016/j.optlastec.2024.111967","DOIUrl":"10.1016/j.optlastec.2024.111967","url":null,"abstract":"<div><div>MIMO FSO (Free Space Optical) systems can provide high data rates through spatial multiplexing or improve transmission reliability using spatial diversity, but atmospheric turbulence is a bottleneck that restricts communication performance. Adaptive transmission technology can effectively suppress the influence of turbulence and improve communication performance. In this paper, switching between spatial multiplexing and diversity is proposed as an adaptive transmission technology for MIMO links to improve the diversity performance of spatial multiplexing of FSO systems. The switching criterion is based on the Minimum Euclidean Distance (MED) of the spatial mapping scheme. The MED expressions for two spatial modes at the receiver are derived, and the bit error rate (BER) approximations are provided, respectively. We evaluate the BER performance of spatial multiplexing and spatial diversity schemes, respectively, taking into account the joint effects of turbulence strengths, pointing error and path loss. To choose the optimal adaptive switching strategy for the system in different signal-to-noise ratio (SNR) ranges, a lookup table for the adaptive switching statistical SNR threshold was created based on the BER curve corresponding to the minimal Euclidean distance. The results show that compared with fixed spatial mode systems, adaptive spatial mode switching systems can achieve significant BER performance gains. The Demmel condition number of matrix channels is considered to provide a sufficient condition for spatial multiplexing to be superior to spatial diversity.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111967"},"PeriodicalIF":4.6,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539674","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}

{"title":"Femtosecond laser-induced hierarchical micro/nanostructures of stainless-steel mesh for oil–water separation and detection of high concentration hydrogen","authors":"Kaishen Chen ,&nbsp;Haiwen Liu ,&nbsp;Runmin Wu ,&nbsp;Hailin Yang ,&nbsp;Duoduo Yang ,&nbsp;Yiping Cheng ,&nbsp;Zhiyu Liu ,&nbsp;Chengyun Zhang","doi":"10.1016/j.optlastec.2024.111981","DOIUrl":"10.1016/j.optlastec.2024.111981","url":null,"abstract":"<div><div>A common method to control the surface wettability of materials is to construct various hierarchical micro/nanostructures followed by surface modification. The femtosecond (fs) laser-induced nanostructures with different morphologies combined with surface modification techniques can be used to adjust the wettability of stainless-steel mesh (SSM). Different micro/nanostructures can be induced by adjusting the fs laser processing parameters, such as laser energy density and scanning interval, transforming the intrinsic slightly hydrophobicity of SSM to hydrophilicity. The hydrophilic surface of fs laser treated-SSM (Fs-SSM) can be used for light oil–water separation with a separation rate of up to 99.64%. Without complex processes and toxic modifiers, the combination of polydimethylsiloxane (PDMS) vapor deposition technology can transform the hydrophilic surface into a hydrophobic surface, achieving the heavy oil–water separation with an average separation efficiency of 99.82%. Moreover, the surface of Fs-SSM coated with palladium (Pd) nanoparticles can be converted from hydrophobic to hydrophilic in hydrogen environment using Pd thermal evaporation coating technology. Upon re-exposure to air, the hydrophobicity of the surface can be restored. This work introduces inventive method to fabricate low-cost, energy-efficient and eco-friendly oil–water separation mesh, while also providing a visual means of detecting higher concentrations of hydrogen.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111981"},"PeriodicalIF":4.6,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539672","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}

{"title":"Heat transfer characteristics and enhancement of weld properties in thin stainless steel using synchronous cold air heat sink assisted laser welding","authors":"Zuguo Liu ,&nbsp;Dabin Zhang ,&nbsp;Xiangzhong Jin ,&nbsp;Chaojing Yu ,&nbsp;Zhengwen Zhang","doi":"10.1016/j.optlastec.2024.111973","DOIUrl":"10.1016/j.optlastec.2024.111973","url":null,"abstract":"<div><div>In this paper, a new type of hybrid laser welding is introduced to weld SUS301 stainless steel. The influence mechanism of synchronous cold air heat sink process on weld pool thermodynamics and weld microstructure during laser welding of SUS301L stainless steel sheet was analyzed by experiment and simulation. Firstly, the dynamic characteristics of the molten pool were analyzed using high-speed camera technology. The results indicate that applying heat sink can significantly reduce the characteristic length of molten pool. When the heat sink flow rate is 200 ml, the length of molten pool increases by 60.6 % as the heat sink distance increases from 5 mm to 20 mm. Furthermore, a simulation model of SHSLW is established. The simulation results illustrate that cold air heat sink will form a rapid cooling zone at the tail of weld pool, which leads to the disappearance of weld comet characteristics, and improves the temperature field at the tail of weld pool, and the refinement mechanism of heat sink on microstructure was described based on the theory of constitutional supercooling (CS). This new understanding provides an opportunity to make better use of heat sink to control grain structure, and in turn to improve the mechanical properties of the welds, which is also verified by the test results of the properties of the welds. EBSD analysis shows that after adding heat sink, the average size of small grains was 8.43 μm, accounting for 74 % of the entire grain area, the proportion of low angle grain boundaries decreased to 59.1 %. Compared with LW, the longitudinal and transverse Vickers hardness values of weld fusion zone under SHSLW are increased by 4.17 % and 7.70 % respectively, the tensile strength and maximum ductility increased by 12.03 % and 21.37 %, respectively. It can be concluded that the application of heat sink is an effective way to improve the tensile strength and toughness of the welds by laser welding of metals.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111973"},"PeriodicalIF":4.6,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539673","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}

{"title":"Computational optical time-domain reflectometry","authors":"Zhi-Han Cao,&nbsp;Dayong Shu,&nbsp;Da-Peng Zhou,&nbsp;Wei Peng","doi":"10.1016/j.optlastec.2024.111952","DOIUrl":"10.1016/j.optlastec.2024.111952","url":null,"abstract":"<div><div>Optical time-domain reflectometry (OTDR) is a well-developed technique detecting returned light signals which are scattered and reflected from the optical fiber when optical pulses are propagating forward along the fiber, providing useful information regarding the characteristics of the optical fiber, indicating loss, locations of faults or connections, etc. The returned signals need to be acquired at a sampling rate satisfying Nyquist–Shannon sampling theorem. In this paper, we propose a computational OTDR based on computational ghost imaging technique in the time domain by sending pre-known pulse sequences and collecting the “integrated” returned light signals, realizing a very different probing and acquiring approach compared to conventional OTDR, reducing sampling rate requirement significantly. Theoretical analysis and mathematical details are given for demonstrating the performance difference of the proposed method using probe sequences derived from a random matrix and an orthogonal matrix. Experiments are carried out to verify the theory indicating that significant improvement in signal-to-noise ratio (SNR) can be achieved using Walsh–Hadamard matrix which is suggested by the theoretical analysis. Finally, we give detailed comparison of the proposed computational OTDR with the conventional technique, showing that sampling rate can be reduced greatly using the computational technique, but it comes with a penalty of requiring more measurements for achieving the same SNR as the conventional technique.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111952"},"PeriodicalIF":4.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539669","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}

{"title":"All-fiber 2 μm high-order-mode light-source based on reconfigurable mode conversion","authors":"Jiali Zhang,&nbsp;Quandong Huang,&nbsp;Fengjiao Li,&nbsp;Xinyong Dong,&nbsp;Ou Xu","doi":"10.1016/j.optlastec.2024.111961","DOIUrl":"10.1016/j.optlastec.2024.111961","url":null,"abstract":"<div><div>We demonstrate an all-fiber reconfigurable high-order-mode light-source generation around 2 μm waveband, which is realized using Tm-doped fiber, multiple-ring few-mode fiber, and alloyed waveguide grating. Mode conversion is carried out by applying loaded pressure on the alloyed waveguide grating, where the applied pressure transfers to the multiple-ring few-mode fiber uniformly. With a 13.0 MPa loaded pressure applied, a smooth spectrum ranging from 1944 nm to 2074 nm for the first high order mode (LP₁₁ mode) is generated as a high order mode light source with a peak power of −32.0 dBm at 2019 nm. The proposed high-order-mode light-source can convert the fundamental mode to any higher order mode by adjusting the alloyed waveguide grating period. The proposed high-order-mode light source in the mid-infrared wavelength band could be a powerful light source for the field of large capacity optical communication and sensing applications.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111961"},"PeriodicalIF":4.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539670","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}

{"title":"Effect of ambient on the dynamics of re-deposition in the rear laser ablation of a thin film","authors":"Renjith Kumar R. ,&nbsp;B.R. Geethika ,&nbsp;Nancy Verma ,&nbsp;Vishnu Chaudhari ,&nbsp;Janvi Dave ,&nbsp;Hem Chandra Joshi ,&nbsp;Jinto Thomas","doi":"10.1016/j.optlastec.2024.111954","DOIUrl":"10.1016/j.optlastec.2024.111954","url":null,"abstract":"<div><div>In this work, we report an innovative pump-probe based experimental set up, to study the melting, subsequent evaporation, plasma formation and re-deposition in a thin film coated on a glass substrate under different ambient conditions and laser fluences. The ambient conditions restrict the expansion of the plasma plume. At high ambient pressure, plume expansion stops closer to the substrate and gets re-deposited at the site of the ablation. This helps in the identification of multiple processes and their temporal evolutions during the melting, expansion and re-deposition stages. The ambient conditions affect the plasma plume formed upon ablation, thus modulating the transmission of probe laser pulses, which provides information about the plume dynamics. Further, the study offers valuable insights into the laser-based ablation of thin film coatings, which will have implications in situ cleaning of view ports on large experimental facilities such as tokamaks and other systems e.g. coating units, pulsed laser deposition, Laser induced forward transfer, Laser surface structuring, etc.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111954"},"PeriodicalIF":4.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539671","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}

{"title":"A 3D analytical model to investigate laser-induced shock wave generation in water","authors":"Mohammad Saeed Ghahramani,&nbsp;Javad Khalilzadeh","doi":"10.1016/j.optlastec.2024.111962","DOIUrl":"10.1016/j.optlastec.2024.111962","url":null,"abstract":"<div><div>Photoacoustic phenomenon offers an efficient means of generating sound pulses. The interaction of laser and plasma is a very crucial subject in the study of the photoacoustic phenomenon. However, existing researches based on the plasma sphere approach, often neglect this interaction, treating the sound wave as a simple output from the plasma. This paper presents a model for analyzing the shock wave resulting from the laser plasma when the nanosecond laser interacts with water. The model calculates key mechanical wave properties, including the shock wave emission time from the the plasma sphere boundary, the initial pressure of the shock wave, and the wave frequency, based on the characteristics of the created plasma. According to the investigations, a laser with a power density of 6 GW.cm⁻² creates a shock wave with an initial pressure of 4.3 MPa and 4520 kHz frequency.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111962"},"PeriodicalIF":4.6,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539668","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}

{"title":"Control resonant excitation of surface plasmon polariton in quantum-dot molecule system via tunneling induced transparency and Autler–Townes splitting","authors":"Akhtar Munir ,&nbsp;Muqaddar Abbas ,&nbsp;Ziauddin ,&nbsp;Chunfang Wang","doi":"10.1016/j.optlastec.2024.111891","DOIUrl":"10.1016/j.optlastec.2024.111891","url":null,"abstract":"<div><div>Electromagnetic induced transparency (EIT) and Autler–Townes splitting (ATS) both produce a transparency window in an absorption profile, yet EIT is distinct in that it can create a transparency window for a weak control field. To elucidate the distinct physical mechanisms underlying EIT and ATS effects, we explore the controlled resonant excitation of surface plasmon polaritons (SPPs) within these regimes. Our setup is composed of three layers: a top vacuum or air layer, a central metal film, and a bottom layer of dielectric medium based on the quantum-dot molecules (QDMs) system. Unlike typical systems, that employ prism or grating coupling scheme, our setup takes advantage of the unique features of the QDMs medium to investigate the direct resonance excitation of SPPs. A weak probe and a strong control field are carried through air or vacuum to the top layer. Our results demonstrate that the permittivity of the bottom medium displays tunneling induced transparency (TIT) if the tunneling strength (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span>) and the decay rate of the direct exciton (<span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>) follow the condition <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>/</mo><msub><mrow><mi>Γ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>⩽</mo><mn>0</mn><mo>.</mo><mn>5</mn></mrow></math></span>; otherwise, it represents the ATS effect. In both instances, the permittivity of the QDMs medium satisfy the low-loss (high transmission) criteria, i.e., Re <span><math><mrow><mrow><mo>[</mo><msub><mrow><mi>ɛ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>]</mo></mrow><mo>&lt;</mo><mn>1</mn></mrow></math></span> and Im <span><math><mrow><mrow><mo>[</mo><msub><mrow><mi>ɛ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>]</mo></mrow><mo>≪</mo><mn>1</mn></mrow></math></span>, providing a framework for exploring the control resonant excitation of SPPs. We simulate the reflection and transmission spectra using the Fresnel’s formula and noticed sharp dips in reflection and peaks in the transmission spectra, which are the signature of coupler free resonance excitation of SPPs. We noticed that the narrow peak in TIT allows for strong light transmission and thus a high peak in SPP resonance excitation, resulting in higher sensitivity in plasmonic sensors. Conversely, the large spacing between the two peaks in the ATS effect broadens the range of effective excitation frequencies for SPPs, increasing the system’s adaptability and efficiency in applications requiring broad spectrum responses.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111891"},"PeriodicalIF":4.6,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444568","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}

{"title":"Comprehensive optimization for full-color holographic stereogram printing system based on single-shot depth estimation and time-controlled exposure","authors":"Anar Khuderchuluun ,&nbsp;Munkh-Uchral Erdenebat ,&nbsp;Erkhembaatar Dashdavaa ,&nbsp;Ki-Chul Kwon ,&nbsp;Seok-Hee Jeon ,&nbsp;Hoonjong Kang ,&nbsp;Nam Kim","doi":"10.1016/j.optlastec.2024.111966","DOIUrl":"10.1016/j.optlastec.2024.111966","url":null,"abstract":"<div><div>A comprehensive optimization method for a full-color holographic stereogram (HS) printing system based on single-shot depth estimation for real-world objects and time-controlled exposure is proposed. Both processing steps, including digital content generation and optical printing, are optimized to ensure possible high-quality three-dimensional (3D) holographic image printing, rapid computation, and proper full-color visualization. In the digital content generation, first a high-resolution two-dimensional (2D) image of the real object is captured, and its depth map is then estimated via a pre-trained convolutional neural network (CNN) model, ensuring an identical resolution with a given 2D image. As a post-processing, the unnecessary scenes and background are removed from the captured color image, without losing the main information of a primary object. Then, a hogel array (HA) is obtained by utilizing the estimated depth map and a post-processed color image through a fast inverse-directed propagation (IDP) method. Each hogel undergoes unique non-iterative phase modulation in a quite short time without the degradation of image quality while the chromatic dispersion errors are minimized. Finally, the hogels are sequentially printed onto holographic material using a time-controlled exposure, to provide the color-balanced full-color reconstruction using a single spatial light modulator (SLM). The overall procedure is seamlessly performed automatically via custom-designed graphical user interface. This study experimentally confirmed a simple and effective optimization for HS printing systems in both digital content generation and optical printing unit.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111966"},"PeriodicalIF":4.6,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444572","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}

{"title":"Fiber Bragg grating tactile perception system based on cross-modal transformer","authors":"Chengang Lyu,&nbsp;Tianle Wang,&nbsp;Ze Zhang,&nbsp;Peiyuan Li,&nbsp;Lin Li,&nbsp;Jiangqianyi Dai","doi":"10.1016/j.optlastec.2024.111917","DOIUrl":"10.1016/j.optlastec.2024.111917","url":null,"abstract":"<div><div>This study proposes a fiber Bragg grating (FBG) tactile sensing system utilizing a cross-modal Transformer architecture. Human tactile perception relies not only on single modalities but also on multimodal perception. Therefore, we decode the collected FBG tactile signals into dynamic vibration and static stress signals, and perform cross-modal perception to enable a robotic hand to perceive tactile properties of touched objects for precise manipulation. Experimental results demonstrate accuracy rates exceeding 87% for identifying the hardness and roughness properties of objects. Furthermore, the system occupies only 2.4 MB of storage space and achieves a recognition time of only 0.92 s per instance. Due to its lightweight and low-latency characteristics, the system holds wide application prospects in the field of tactile perception, including smart manufacturing, virtual reality, and online healthcare.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111917"},"PeriodicalIF":4.6,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444569","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}