Optics and Laser Technology最新文献

{"title":"Photonic technique for unambiguous AOA measurement without knowing incoming RF signal power","authors":"Aoqi Li,&nbsp;Hao Chen,&nbsp;Erwin H.W. Chan","doi":"10.1016/j.optlastec.2025.112830","DOIUrl":"10.1016/j.optlastec.2025.112830","url":null,"abstract":"<div><div>A technique that is capable of determining an RF signal angle-of-arrival (AOA) unambiguously over a wide measurement range without knowing the power of the incoming RF signal is presented. It is implemented in a microwave photonic system using a dual-polarisation Mach Zehnder modulator followed by optical filters, and a pair of polarisation beam splitters and low-speed balanced photodetectors. Two DC voltages are generated at the balanced detector outputs. The DC voltages as a function of the input RF signal phase difference have a sine–cosine behaviour. This enables the RF signal phase difference in the range of ±180°, which corresponds to a full ±90° AOA measurement range, to be determined unambiguously simply using the ratio of the two system output DC voltages. Hence, knowing the power of the incoming RF signal is not required but is needed in many reported structures for AOA measurement. The proposed photonic-assisted AOA measurement system is free of microwave components and can measure an RF signal AOA instantaneously. Experiments have been conducted to demonstrate the concept of the proposed technique. Measured results demonstrate AOA measurement in the range of −70.8° to 70.8° with errors less than ±2.2°, for different input RF signal frequencies, without requiring knowledge of the input RF signal power.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112830"},"PeriodicalIF":4.6,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680078","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}

{"title":"Negative effect of bismuth nanoparticles upon the luminescent properties of bismuth active centers in bismuth doped fiber","authors":"Yanmei Wang ,&nbsp;Yanhua Luo ,&nbsp;Jianxiang Wen ,&nbsp;Yanhua Dong ,&nbsp;Tingyun Wang ,&nbsp;Chengbo Mou ,&nbsp;Wei Chen ,&nbsp;Fufei Pang ,&nbsp;Weiwen Zou ,&nbsp;Ryszard Buczynski ,&nbsp;Gang-Ding Peng","doi":"10.1016/j.optlastec.2025.112844","DOIUrl":"10.1016/j.optlastec.2025.112844","url":null,"abstract":"<div><div>The previous studies have shown that the presence of bismuth (Bi) nanoparticles in bismuth-doped fibers (BDFs) will lead to the decrease of the luminescence responsible from bismuth active centers (BACs). To better understand the characteristics of BACs, this study examines the effect of Bi nanoparticles on the spectral intensity of BDFs from the aspects of host materials, BAC types, temperature, and excitation photon energy. A first-order reaction kinetic model incorporating the photocatalytic process of Bi nanoparticles, based on the theory of interband plasmon resonance, was established to investigate the intrinsic relation between Bi nanoparticles and BAC deactivation. By comparing the constants of thermal activation rate and thermal deactivation rate of BAC-Si in thermal annealing with dwelling time of 60 and 120 s, it was found that the latter case is significantly higher than the former at over 600 °C. Specifically, the thermal activation rate reaches up to 12.19 times at 800 °C. Such observation is resulted from the competitive interaction between the photocatalytic process of Bi nanoparticles and the thermal deactivation of BAC, associated with the valence state differences of Bi ions in BACs responsible for the same luminescence band. Additionally, it was found that the ionization of BACs caused by the photocatalytic effect of Bi nanoparticles is not only proportional to the irradiation wavelength, but also related to the local dielectric properties of BACs. By comparing the normalized ionization rates of different BACs under pumping at wavelengths ranging from 407 to 1460 nm, the values of the imaginary part of the local dielectric constant are in the order of BAC-Si &lt; BAC-P &lt; BAC-Al &lt; BAC-Ge. Especially, BAC-Ge is more susceptible to ionization and inactivation due to the enhanced photocatalytic effect of Bi nanoparticles.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112844"},"PeriodicalIF":4.6,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680110","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":"Tongue-parallel probe-based microcirculation monitoring and automated sublingual vessel estimation","authors":"Ping Tang ,&nbsp;Chongzhao Wu ,&nbsp;Xiaomei Chi ,&nbsp;Borui Xu ,&nbsp;Bo Chen ,&nbsp;Yudong Tian ,&nbsp;Xiangyu Zhao ,&nbsp;Jingjing Xue ,&nbsp;Han Lu ,&nbsp;Buwei Yu","doi":"10.1016/j.optlastec.2025.112803","DOIUrl":"10.1016/j.optlastec.2025.112803","url":null,"abstract":"<div><div>Assessment of the perfusion state of capillaries provides important guidance in diagnosis and treatment of critically ill patients, resulting in a strong clinical demand for high-quality optical capture of microcirculation and effective methods of vessel analysis. In this work, a systematic monitoring framework for sublingual microcirculation is proposed, including both optical imaging device and automated vessel analysis. To solve the challenges in conventional vertical-capture manner for sublingual microcirculation monitoring, which is bulk and heavy, a novel parallel probe-based sidestream dark-field (PP-SDF) imaging device is designed and experimentally demonstrated, which utilizes a front-end probe parallel to the inferior surface of tongue to reduce the force imposed on sublingual tissues. Then a multi-stage scheme is proposed for automated vessel analysis, including Minimum Output Sum of Squared Error (MOSSE) filtering based fast video stabilization, U-Net based vessel segmentation, and Convolutional Neural Network-Bidirectional Long Short-Term Memory (CNN-BiLSTM) based blood velocity estimation. Experiments for monitoring of human sublingual microcirculation demonstrate the high performance of the proposed PP-SDF device and the automated vessel analysis framework. This monitoring system is expected to be widely applied in clinical detection of microcirculation in the future.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112803"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680074","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 localized electrodeposition of two dimensional metal patterns","authors":"Hanhan Wei ,&nbsp;Wanfei Ren ,&nbsp;Jinkai Xu ,&nbsp;Guodong Zhang ,&nbsp;Jiaji Cao ,&nbsp;Zhaoqiang Zou","doi":"10.1016/j.optlastec.2025.112854","DOIUrl":"10.1016/j.optlastec.2025.112854","url":null,"abstract":"<div><div>Microscale metal patterns find extensive applications in solar cells, flexible electrodes, and metal gratings. Traditional techniques for manufacturing metal patterns generally require masks, and they are also time-consuming and inefficient. In the present experiment, an innovative femtosecond (fs) laser-induced local electrodeposition (FsLI-LECD) method was proposed. The introduction of the fs laser significantly enhanced the current density within the target region, enabling the efficient and maskless fabrication of copper (Cu) patterns. The impact of the fs laser on cathode current density was analyzed through theoretical and numerical calculations. The accuracy of the theoretical and numerical results was validated by examining the current curves at different laser single pulse energies. The composition, morphology, deposition rate, and dimensional accuracy of the coating were evaluated at different laser single pulse energies. It was found that the fs laser irradiation increased the cathode current density. The fs laser had a small thermal influence zone; thus, structural deposition at the microscale was realized. At a single pulse energy of 8 µJ, the coverage of the deposited structure at the fs laser-induced track was higher and the cathode current increased by 28 % compared with that without fs laser irradiation. Moreover, the volume deposition rate achieved an impressive value of 6.61 × 10³ μm³/s, enabling the high-efficiency fabrication of complex patterns. The Cu patterns have a hardness of 1.42 GPa, which is close to that of bulk copper. This proposed innovative approach presents a novel fabrication solution for large-area, multi-metal patterns.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112854"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680076","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":"Impact of NiCrAlY-APS coating laser remelting on high-temperature oxidation resistance","authors":"Mohammad Gavahian Jahromi,&nbsp;Reza Shoja Razavi,&nbsp;Zia Valefi,&nbsp;Hamed Naderi-Samani,&nbsp;Saeid Taghi-Ramezani","doi":"10.1016/j.optlastec.2025.112743","DOIUrl":"10.1016/j.optlastec.2025.112743","url":null,"abstract":"<div><div>This research focused on enhancing the high-temperature oxidation resistance of NiCrAlY-APS coatings by modifying their surface through remelting with a continuous fiber laser. The process parameters included laser power and scan rate. The high-temperature oxidation test was conducted for 200 h at a temperature of 1,100 °C. An examination of the coating was done by applying optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Following 200 h oxidation at a temperature of 1100 °C, the original coating displayed combination of aluminum oxide and spinel. The laser remelting process for the purpose of modifying the surface ensured uniform growth aluminum oxide layer (α-Al₂O₃) the oxidation examination. Following 200 h of oxidation at a temperature of 1100 °C, the original coating displayed combination of aluminum oxide and spinel. The surface remelting process for the purpose of modifying the surface ensured uniform growth aluminum oxide layer (α-Al₂O₃) the oxidation examination. The reduction in grain size which is caused by laser remelting could prevent Al₂O₃ oxide wrinkling. Laser remelting creates Y-Al particles on the coating’s surface, which, in turn, create sites for oxidation without diffusion. This leads to α-Al₂O₃ phase formation in the oxidation’s initial stages. Ultimately, this process ensures long-term thermodynamic stability. Such a process could serve as a new and alternative approach for modifying MCrAlY coatings.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112743"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680077","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":"Cascade time-lens","authors":"Sara Meir,&nbsp;Hamootal Duadi,&nbsp;Yuval Tamir,&nbsp;Moti Fridman","doi":"10.1016/j.optlastec.2025.112745","DOIUrl":"10.1016/j.optlastec.2025.112745","url":null,"abstract":"<div><div>Temporal optics rises from the equivalence between light diffraction in free space and pulse dispersion in dispersive media, paving the way for the development of temporal devices and applications, such as time-lenses. A Four-wave mixing based time-lens allows single-shot measurements of ultra-short signals in high temporal resolution by imaging signals, and inducing temporal Fourier transform. We introduce a cascade time-lens by utilizing a cascade FWM process within the time-lens. We theoretically develop and experimentally demonstrate the cascade time-lens, and confirm that different cascade orders correspond to different effective temporal systems, leading to measuring in various temporal imaging configurations simultaneously with a single optical setup. This approach can simplify experiments and provide a more comprehensive view of a signal’s phase and temporal structure. Such capabilities are useful in fields like ultrafast optics, communications, and quantum measurements, where understanding the precise timing and shape of short pulses of light is important.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112745"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680068","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":"Tunable multi-wavelength mode-locked thulium-doped fiber laser with precise controlled wavelength spacing via Mach-Zehnder interferometer","authors":"Qian Zhang ,&nbsp;Xiao Dai ,&nbsp;Huizheng Li ,&nbsp;Xinxin Jin ,&nbsp;Qing Wu","doi":"10.1016/j.optlastec.2025.112840","DOIUrl":"10.1016/j.optlastec.2025.112840","url":null,"abstract":"<div><div>This study presents an experimental demonstration of a multi-wavelength mode-locked Thulium-doped fiber laser (TDFL) utilizing a cost-effective, fully fiber-integrated Mach-Zehnder interferometer (MZI) as the spectral filter. The working mechanism of the MZI filter is analyzed, demonstrating its role in shaping the laser spectrum and providing precise bandwidth control. The MZI operates by inducing interference between its two arms, where the arm length difference (<em>ΔL</em>) determines the free spectral range (FSR). By adjusting <em>ΔL</em>, the FSR and, consequently, the pulse wavelength spacing can be precisely controlled. Simulated transmission spectra confirm the filter’s tunability and precision. The laser cavity integrates the MZI filter with a polarization controller (PC) and black phosphorus in a hybrid mode-locking scheme. The MZI acts as a comb filter, while the PC and black phosphorus facilitate mode-locked operation. Adjusting the PC alters the refractive index of the fiber, dynamically tuning the filtering wavelength within the cavity. This configuration enables a tunable single-wavelength output spanning 1842.1 nm to 1897.9 nm, covering a 55.8 nm range. By varying the pump power, the laser transitions from single-wavelength to four-wavelength mode-locking. This innovative design highlights the potential of the MZI filter in improving the performance and versatility of Thulium-doped fiber lasers, offering promising applications in wavelength-selective optical sensing and diagnostics.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112840"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680070","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}

{"title":"Tunable self-injection-locked narrow-linewidth laser based on thin-film lithium niobate","authors":"Ting Huang ,&nbsp;Zhe Wang ,&nbsp;Zhiwei Fang ,&nbsp;Yu Ma ,&nbsp;Yuan Zhou ,&nbsp;Jian Liu ,&nbsp;Jian Xu ,&nbsp;Ya Cheng","doi":"10.1016/j.optlastec.2025.112806","DOIUrl":"10.1016/j.optlastec.2025.112806","url":null,"abstract":"<div><div>We demonstrate an electro-optically tunable narrow-linewidth 1550 nm laser based on thin-film lithium niobate. By self-injecting a 1550 nm seed laser into a high-Q lithium niobate microring resonator, the linewidth of the output laser is significantly narrowed. On-chip integration of microelectrodes is further performed to obtain low-voltage and wide-spectral tuning, resulting in an electro-optical efficiency of 2.95  pm/V with good linearity. With an applied voltage of −10 to 10 V, the laser can achieve a wavelength tuning capability of ∼50 pm near 1552 nm. The demonstrated electrooptically tunable laser holds great potential for various applications in optical communications, LiDAR, and spectroscopy.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112806"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680072","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":"Numerical simulation and experimental research of the temperature field and flow field in the molten pool under different process parameters based on hollow-laser directed energy deposition","authors":"Lele Zhao ,&nbsp;Gangxian Zhu ,&nbsp;Jiaqin Luo ,&nbsp;Hang Zhou ,&nbsp;Jiaqiang Li ,&nbsp;Xing Zhang ,&nbsp;Lifang Wang","doi":"10.1016/j.optlastec.2025.112842","DOIUrl":"10.1016/j.optlastec.2025.112842","url":null,"abstract":"<div><div>Hollow-laser Direct Energy Deposition (HL-DED) technology has significant advantages in terms of energy distribution and process stability. In this paper, the HL-DED process is systematically studied by means of numerical simulation and experimental research. The morphology of the cladding layer, the temperature field and flow field of the molten pool under different process parameters are analysed. Results show that the maximum temperature and flow velocity of the molten pool are positively correlated with the laser power and negatively correlated with the powder feed and scanning speed. Increasing laser power from 1200 W to 1800 W elevates the maximum temperature (1977 K to 2640 K) and flow velocity (0.221 m/s to 0.301 m/s). Conversely, raising the powder feed rate from 6 g/min to 12 g/min reduces the maximum temperature (2450 K to 2000 K) and flow rate (0.379 m/s to 0.249 m/s). Similarly, increasing the scanning speed from 4 mm/s to 10 mm/s decreases the maximum temperature (2300 K to 1950 K) and flow rate (0.320 m/s to 0.146 m/s). When the substrate tilting angle is increased from 0° to 90°, the molten pool exhibits a peak offset of 172 μm, while the maximum temperature remains stable at approximately 2000 K. The internal flow field transitions from symmetric to highly asymmetric, with the average flow velocity increasing (0.260 m/s to 0.281 m/s). These findings highlight the significant influence of process parameters on molten pool dynamics, providing critical insights for optimizing laser additive manufacturing processes.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112842"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680073","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":"Residual stress and solidification structure control of additive manufactured based 316L utilizing in-layer dwell time in laser additive manufacturing","authors":"Zhou Yan ,&nbsp;Jia Guo ,&nbsp;Lijun Song","doi":"10.1016/j.optlastec.2025.112760","DOIUrl":"10.1016/j.optlastec.2025.112760","url":null,"abstract":"<div><div>The rapid solidification and associated thermal cycles encountered during additive manufacturing (AM) introduce significant residual stresses within the fabricated components. These stresses often lead to part deformation and have detrimental effects on the mechanical properties of the final product. In this study, we investigate the application of Laser Dwell Technology, specifically in Dwell Continuous Laser Wave mode (DCW), within laser additive manufacturing processes. Our findings demonstrate that residual stress exhibits a decreasing trend over time, with a maximum residual stress of 600 MPa being reduced by 83.3 % to 100 MPa under the same laser power (500 W). Furthermore, we examine the influence of different laser modes on the stability of the molten pool boundary and the resulting solidification microstructure in 316L stainless steel during laser additive manufacturing. Compared to the variable molten pool boundaries observed in Continuous-Wave Laser Additive Manufacturing (CW-LAM), Direct Current Wave Laser Additive Manufacturing (DCW-LAM) is characterized by enhanced molten pool boundary stability and in-situ high-frequency remelting. In the case of the same laser power (500 W), under varying laser power modes parallel to the build direction, DCW-LAM demonstrates a 35 % increase in yield strength and a 13.6 % improvement in ultimate tensile strength compared to CW-LAM. These improvements occur from the facilitation of continuous epitaxial development of columnar dendrites, which results in a highly orientated columnar structure and improved mechanical characteristics due to higher dislocation density. This study offers a novel approach for regulating residual stress and controlling solidification structures in laser additive manufacturing.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112760"},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680075","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}