Pub Date : 2024-09-06DOI: 10.1016/j.optlastec.2024.111741
Hui Li, Tianlin Zhu, Xudong Lin, Chengkai Zhou, Peng Wang, Jiali Feng, Jinhao Wang, Xuan Wang, Xianlin Wu, Xida Han, Ming Li
The utilization of array detection technology is pivotal in augmenting the capability of laser ranging systems to detect echo signals. It can amplify the likelihood of successful detection. But there will be variations amongst the channels due to the array detector’s inconsistency. A response time model is developed based on the detection mechanism of superconducting nanowire single photon detectors (SNSPD). This model is employed in conjunction with ground target calibration measurements to rectify time bias among the channels within the 4-channel Satellite Laser Ranging (SLR) system. The findings indicate that this method adeptly manages channel deviations and mitigates data fluctuations by rectifying the inherent range walk error of SLR measurement data, resulting in improved data quality. The average precision of satellite measurement data in the first half of 2024 increased by .
{"title":"Processing method of laser ranging data based on array of superconducting nanowire single photon detector","authors":"Hui Li, Tianlin Zhu, Xudong Lin, Chengkai Zhou, Peng Wang, Jiali Feng, Jinhao Wang, Xuan Wang, Xianlin Wu, Xida Han, Ming Li","doi":"10.1016/j.optlastec.2024.111741","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111741","url":null,"abstract":"The utilization of array detection technology is pivotal in augmenting the capability of laser ranging systems to detect echo signals. It can amplify the likelihood of successful detection. But there will be variations amongst the channels due to the array detector’s inconsistency. A response time model is developed based on the detection mechanism of superconducting nanowire single photon detectors (SNSPD). This model is employed in conjunction with ground target calibration measurements to rectify time bias among the channels within the 4-channel Satellite Laser Ranging (SLR) system. The findings indicate that this method adeptly manages channel deviations and mitigates data fluctuations by rectifying the inherent range walk error of SLR measurement data, resulting in improved data quality. The average precision of satellite measurement data in the first half of 2024 increased by .","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the laser powder bed fusion (L-PBF) process, the incorporation of in-situ monitoring systems plays a vital role in guaranteeing the quality of the additive manufacturing (AM) process. Nevertheless, the monitoring system based on high-speed cameras is hindered by the high cost of the required high-speed cameras, making it difficult to achieve accurate in-situ monitoring. This paper studies in-situ video frame interpolation and super resolution reconstruction for accurate monitoring of L-PBF process. It introduces a novel in-situ video frame interpolation algorithm, termed CS-EMA-VFI, aiming to improve the temporal resolution of monitoring video. The visual transformer-based video super resolution (ViTSR) algorithm was employed to enhance the spatial resolution of the interpolated video. A U-Net algorithm was utilized for extracting the geometric characteristics of the molten pool during the L-PBF process subsequent to video frame interpolation and super resolution reconstruction. Comparing the CS-EMA-VFI with seven state-of-the-art video frame interpolation methods, the CS-EMA-VFI achieves the highest peak signal-to-noise ratio (PSNR) of 28.16 dB and the highest structural similarity index measure (SSIM) of 0.917 while being lightweight. The ViTSR achieved PSNR of 28.18 dB and 25.31 dB on the original video sequence and interpolated video sequence, respectively. The inference time for the CS-EMA-VFI with fixed timestep, ViTSR, and U-Net were recorded as 18.5 ms, 48.0 ms, and 20.5 ms, respectively. The total inference time of the three-stage strategy varies from 87.0 ms to 142.5 ms, depending on the temporal resolution enhancement multiples. Additionally, the proposed three-stage method achieves a segmentation accuracy of 90.15 % with fixed timestep interpolation, simultaneously enhancing temporal and spatial resolution, thus enabling accurate and real-time monitoring. This paper promotes the wide adoption of in-situ monitoring system in the AM field.
{"title":"In-situ video frame interpolation and super resolution reconstruction for accurate monitoring of L-PBF process","authors":"Rongzhe Ma, Hui Li, Shengnan Shen, Wenkang Zhu, Jiahong Chen, Minjie Wang, Hua Tu, Yajun Jiang","doi":"10.1016/j.optlastec.2024.111727","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111727","url":null,"abstract":"In the laser powder bed fusion (L-PBF) process, the incorporation of in-situ monitoring systems plays a vital role in guaranteeing the quality of the additive manufacturing (AM) process. Nevertheless, the monitoring system based on high-speed cameras is hindered by the high cost of the required high-speed cameras, making it difficult to achieve accurate in-situ monitoring. This paper studies in-situ video frame interpolation and super resolution reconstruction for accurate monitoring of L-PBF process. It introduces a novel in-situ video frame interpolation algorithm, termed CS-EMA-VFI, aiming to improve the temporal resolution of monitoring video. The visual transformer-based video super resolution (ViTSR) algorithm was employed to enhance the spatial resolution of the interpolated video. A U-Net algorithm was utilized for extracting the geometric characteristics of the molten pool during the L-PBF process subsequent to video frame interpolation and super resolution reconstruction. Comparing the CS-EMA-VFI with seven state-of-the-art video frame interpolation methods, the CS-EMA-VFI achieves the highest peak signal-to-noise ratio (PSNR) of 28.16 dB and the highest structural similarity index measure (SSIM) of 0.917 while being lightweight. The ViTSR achieved PSNR of 28.18 dB and 25.31 dB on the original video sequence and interpolated video sequence, respectively. The inference time for the CS-EMA-VFI with fixed timestep, ViTSR, and U-Net were recorded as 18.5 ms, 48.0 ms, and 20.5 ms, respectively. The total inference time of the three-stage strategy varies from 87.0 ms to 142.5 ms, depending on the temporal resolution enhancement multiples. Additionally, the proposed three-stage method achieves a segmentation accuracy of 90.15 % with fixed timestep interpolation, simultaneously enhancing temporal and spatial resolution, thus enabling accurate and real-time monitoring. This paper promotes the wide adoption of in-situ monitoring system in the AM field.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"81 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.optlastec.2024.111718
Yu-Peng Li, Zi-Han Guo, Hai-Feng Zhang
The present study introduces a comprehensive theoretical design that demonstrates the unique advantages of the Spoof Surface Plasmon Polariton (SSPP) mode in achieving the Absorption-Transmission Window (A-TW) effect, thereby enabling the perfect integration of the SSPP mode with the Frequency Selective Rasorber (FSR). This paper analyzes the main reasons for the coexistence of electromagnetic wave (EMW) transmission and absorption effects, thereby confirming the confining effect of localized fields in the SSPP mode on EMW. Additionally, the distinct dispersion characteristics of the structure are investigated, showcasing the remarkable capability of dispersion engineering in generating customized absorption bands. The results indicate that the aforementioned FSR exhibits absorption abilities of over 90 % for positively incident EMWs in the frequency ranges of 1.44 ∼ 2.04 THz and 4.65 ∼ 5.44 THz, while also making constructive contributions to the formation of the transmission window (TW) in 2.61 ∼ 4.07 THz. Exploring the asymmetric response of EMWs reveals that the FSR exhibits a pseudo-Reflection-Transmission Window (R-TW) effect when excited by reverse-propagating EMWs. This paper proposes an FSR based on the SSPP mode, exhibiting asymmetric EMW response, and hopefully contributes a new perspective for the application and theoretical analysis of the SSPP mode.
{"title":"Dispersion characteristics-based asymmetric frequency selective rasorber using spoof surface plasmon polariton mode","authors":"Yu-Peng Li, Zi-Han Guo, Hai-Feng Zhang","doi":"10.1016/j.optlastec.2024.111718","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111718","url":null,"abstract":"The present study introduces a comprehensive theoretical design that demonstrates the unique advantages of the Spoof Surface Plasmon Polariton (SSPP) mode in achieving the Absorption-Transmission Window (A-TW) effect, thereby enabling the perfect integration of the SSPP mode with the Frequency Selective Rasorber (FSR). This paper analyzes the main reasons for the coexistence of electromagnetic wave (EMW) transmission and absorption effects, thereby confirming the confining effect of localized fields in the SSPP mode on EMW. Additionally, the distinct dispersion characteristics of the structure are investigated, showcasing the remarkable capability of dispersion engineering in generating customized absorption bands. The results indicate that the aforementioned FSR exhibits absorption abilities of over 90 % for positively incident EMWs in the frequency ranges of 1.44 ∼ 2.04 THz and 4.65 ∼ 5.44 THz, while also making constructive contributions to the formation of the transmission window (TW) in 2.61 ∼ 4.07 THz. Exploring the asymmetric response of EMWs reveals that the FSR exhibits a pseudo-Reflection-Transmission Window (R-TW) effect when excited by reverse-propagating EMWs. This paper proposes an FSR based on the SSPP mode, exhibiting asymmetric EMW response, and hopefully contributes a new perspective for the application and theoretical analysis of the SSPP mode.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"285 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.optlastec.2024.111747
Huachen Li, Li Cui, Dingyong He, Zhenfu Shi, Fanhui Bu, Qing Cao, Shengjun Wan
In order to study the effect of non-contact ultrasonic-assisted laser metal deposition (LMD) on microcracks, Fe-based powders were deposited on a 42CrMoA steel using LMD process at different excitation distances (). The results show that the maximum length of microcracks is 112.3 μm under the condition without ultrasonic-assisted. When = 50 mm, a crack of less than 10 μm is generated at the bottom of deposition layer. When = 110 mm, the microcrack maximum length is 84.4 μm. The deposition layer with no microcracks was obtained when = 80 mm. Ultrasonic-assisted application can synergically inhibit the generation of cracks from two aspects. On the one hand, it makes the distribution of B element more uniform in the molten pool, and the accumulation of borides at the bottom of the deposition layer easily generates hard and brittle borides such as M(C,B), which is more likely to induce cracks. After non-contact ultrasonic-assisted, the width of boride is 54.2 % lower than that without ultrasonic-assisted, and the boride morphology is slightly different. The borides changed from long rod-shape and mesh-shape to nanoscale short rod-shape and granular-shape. On the other hand, it can make the microscopic stress distribution at the bottom of deposition layer more uniform, which reduces the crack sensitivity. Compared to the condition without ultrasonic-assisted, when is 50 mm, 80 mm and 110 mm, the KAM average value decreased by 44.03 %, 40.36 % and 19.27 %, respectively.
为了研究非接触超声波辅助激光金属沉积（LMD）对微裂纹的影响，使用 LMD 工艺在 42CrMoA 钢上以不同的激发距离（）沉积了铁基粉末。结果表明，在无超声波辅助条件下，微裂纹的最大长度为 112.3 μm。当 = 50 mm 时，沉积层底部会产生小于 10 μm 的裂纹。当 = 110 mm 时，微裂纹最大长度为 84.4 μm。当 = 80 毫米时，沉积层无微裂纹。超声波辅助应用可以从两个方面协同抑制裂纹的产生。一方面，它使 B 元素在熔池中的分布更加均匀，而硼化物在沉积层底部的堆积容易产生硬脆的硼化物，如 M(C,B)，从而更容易诱发裂纹。非接触超声波辅助后，硼化物的宽度比未超声波辅助时减少了 54.2%，硼化物的形态也略有不同。硼化物从长棒状和网状变为纳米级短棒状和颗粒状。另一方面，超声波辅助可使沉积层底部的微观应力分布更加均匀，从而降低裂纹敏感性。与未使用超声波辅助的情况相比，在 50 mm、80 mm 和 110 mm 时，KAM 平均值分别降低了 44.03 %、40.36 % 和 19.27 %。
{"title":"Effect of ultrasonic-assisted laser metal deposition on microcracks in deposition layer","authors":"Huachen Li, Li Cui, Dingyong He, Zhenfu Shi, Fanhui Bu, Qing Cao, Shengjun Wan","doi":"10.1016/j.optlastec.2024.111747","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111747","url":null,"abstract":"In order to study the effect of non-contact ultrasonic-assisted laser metal deposition (LMD) on microcracks, Fe-based powders were deposited on a 42CrMoA steel using LMD process at different excitation distances (). The results show that the maximum length of microcracks is 112.3 μm under the condition without ultrasonic-assisted. When = 50 mm, a crack of less than 10 μm is generated at the bottom of deposition layer. When = 110 mm, the microcrack maximum length is 84.4 μm. The deposition layer with no microcracks was obtained when = 80 mm. Ultrasonic-assisted application can synergically inhibit the generation of cracks from two aspects. On the one hand, it makes the distribution of B element more uniform in the molten pool, and the accumulation of borides at the bottom of the deposition layer easily generates hard and brittle borides such as M(C,B), which is more likely to induce cracks. After non-contact ultrasonic-assisted, the width of boride is 54.2 % lower than that without ultrasonic-assisted, and the boride morphology is slightly different. The borides changed from long rod-shape and mesh-shape to nanoscale short rod-shape and granular-shape. On the other hand, it can make the microscopic stress distribution at the bottom of deposition layer more uniform, which reduces the crack sensitivity. Compared to the condition without ultrasonic-assisted, when is 50 mm, 80 mm and 110 mm, the KAM average value decreased by 44.03 %, 40.36 % and 19.27 %, respectively.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.optlastec.2024.111731
Alejandro Rosado, Ignacio Esquivias
We propose the use of the Gerchberg–Saxton algorithm to retrieve the time-resolved phase of optical pulses generated by gain-switched semiconductor lasers from the temporal and spectral intensities measured with standard instrumentation. We analyze numerically and experimentally the conditions for retrieving the optical phase and the corresponding time-resolved frequency chirp. The numerical analysis examines the performance of the algorithm under different gain switching conditions, with a particular emphasis on the number of points, the resolution of the input data and the choice of the initial phase seed. The results of this numerical analysis show that the algorithm converges effectively over a wide range of conditions, almost independently of the chosen phase seed and the number of points of the input data. We have experimentally retrieved the phase of optical pulses generated by a gain-switched 1550 nm laser diode. The retrieved frequency chirp was used for the experimental determination of the linewidth enhancement factor, resulting in a simple and robust technique for estimating this parameter.
{"title":"Complete optical field reconstruction and determination of linewidth enhancement factor in gain-switched semiconductor lasers using the Gerchberg–Saxton algorithm","authors":"Alejandro Rosado, Ignacio Esquivias","doi":"10.1016/j.optlastec.2024.111731","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111731","url":null,"abstract":"We propose the use of the Gerchberg–Saxton algorithm to retrieve the time-resolved phase of optical pulses generated by gain-switched semiconductor lasers from the temporal and spectral intensities measured with standard instrumentation. We analyze numerically and experimentally the conditions for retrieving the optical phase and the corresponding time-resolved frequency chirp. The numerical analysis examines the performance of the algorithm under different gain switching conditions, with a particular emphasis on the number of points, the resolution of the input data and the choice of the initial phase seed. The results of this numerical analysis show that the algorithm converges effectively over a wide range of conditions, almost independently of the chosen phase seed and the number of points of the input data. We have experimentally retrieved the phase of optical pulses generated by a gain-switched 1550 nm laser diode. The retrieved frequency chirp was used for the experimental determination of the linewidth enhancement factor, resulting in a simple and robust technique for estimating this parameter.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.optlastec.2024.111538
Weihao Xu, Songmao Chen, Dingjie Wang, Yuyuan Tian, Ning Zhang, Wei Hao, Xiuqin Su
Non-line-of-sight (NLoS) imaging reveals hidden scene from indirect diffusion signals. However, it is still challenging to balance noise suppression, detail preservation, and reconstruction efficiency. In this work, a robust framework which is centered on feature extractor and enhancement is proposed. In the framework, the feature extractor exploits the graph model in latent space for efficient noise suppression and detail preservation, the enhancement collaboratively learns the feature and data statistics by considering the extractor to define regularization. The reconstruction results on the publicly accessible datasets show that the proposed framework outperforms the state-of-art methods considering both quality and efficiency.
{"title":"Feature enhanced non-line-of-sight imaging using graph model in latent space","authors":"Weihao Xu, Songmao Chen, Dingjie Wang, Yuyuan Tian, Ning Zhang, Wei Hao, Xiuqin Su","doi":"10.1016/j.optlastec.2024.111538","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111538","url":null,"abstract":"Non-line-of-sight (NLoS) imaging reveals hidden scene from indirect diffusion signals. However, it is still challenging to balance noise suppression, detail preservation, and reconstruction efficiency. In this work, a robust framework which is centered on feature extractor and enhancement is proposed. In the framework, the feature extractor exploits the graph model in latent space for efficient noise suppression and detail preservation, the enhancement collaboratively learns the feature and data statistics by considering the extractor to define regularization. The reconstruction results on the publicly accessible datasets show that the proposed framework outperforms the state-of-art methods considering both quality and efficiency.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.optlastec.2024.111623
Huanyu Yang, Zhigang Cheng, Xingkong Tao, Liming Liu
In order to study the heat source characteristics and discharge mechanism of low power pulse laser induced arc/double arc hybrid welding technology in the narrow gap backing welding process of titanium alloy medium-thick plate, laser-TIG (L-TIG) hybrid welding and laser-double TIG (L-DTIG) hybrid welding technology were used in this paper. Welding experiments were carried out under different blunt edge thicknesses. Two kinds of welding methods were used to compare the influence of the temperature field of the weld, the morphology of the coupled plasma and the energy distribution of the plasma, the coupling driving force and the force state of the plasma, and the influence of the microstructure and properties of the weld. The results show that the welding heat input of L-DTIG is significantly lower than that of L-TIG hybrid heat source, and there is a larger process interval in the backing welding of different blunt edge thicknesses. Under the action of pulsed laser, the L-DTIG hybrid heat source plasma has a larger central conductive area and electron density, which are 1.68 times and 1.42 times of the L-TIG hybrid heat source, respectively. Due to the small heat input of L-DTIG hybrid welding, the grain size is significantly reduced, so that the hardness of the weld zone and the heat affected zone is slightly higher than that of the L-TIG hybrid heat source, and the hardness distribution from the weld center to the base metal shows a downward trend. Due to the stronger induction and compression ability of the pulsed laser to the double TIG arc, the energy density of the L-DTIG hybrid heat source is more concentrated, which is beneficial to reduce the welding heat input and improve the welding efficiency and the overall performance of the welded joint.
{"title":"Characterization of low-power pulsed laser-induced single/double arc hybrid heat source bottoming welding of medium-thick plate titanium alloy","authors":"Huanyu Yang, Zhigang Cheng, Xingkong Tao, Liming Liu","doi":"10.1016/j.optlastec.2024.111623","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111623","url":null,"abstract":"In order to study the heat source characteristics and discharge mechanism of low power pulse laser induced arc/double arc hybrid welding technology in the narrow gap backing welding process of titanium alloy medium-thick plate, laser-TIG (L-TIG) hybrid welding and laser-double TIG (L-DTIG) hybrid welding technology were used in this paper. Welding experiments were carried out under different blunt edge thicknesses. Two kinds of welding methods were used to compare the influence of the temperature field of the weld, the morphology of the coupled plasma and the energy distribution of the plasma, the coupling driving force and the force state of the plasma, and the influence of the microstructure and properties of the weld. The results show that the welding heat input of L-DTIG is significantly lower than that of L-TIG hybrid heat source, and there is a larger process interval in the backing welding of different blunt edge thicknesses. Under the action of pulsed laser, the L-DTIG hybrid heat source plasma has a larger central conductive area and electron density, which are 1.68 times and 1.42 times of the L-TIG hybrid heat source, respectively. Due to the small heat input of L-DTIG hybrid welding, the grain size is significantly reduced, so that the hardness of the weld zone and the heat affected zone is slightly higher than that of the L-TIG hybrid heat source, and the hardness distribution from the weld center to the base metal shows a downward trend. Due to the stronger induction and compression ability of the pulsed laser to the double TIG arc, the energy density of the L-DTIG hybrid heat source is more concentrated, which is beneficial to reduce the welding heat input and improve the welding efficiency and the overall performance of the welded joint.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.optlastec.2024.111684
Shan Yin, Haotian Zhong, Wei Huang, Wentao Zhang
Metamaterials open up a new way to manipulate electromagnetic waves and realize various functional devices. Metamaterials with high-quality factor (Q) resonance responses are widely employed in sensing, detection, and other applications. Traditional design of metamaterials involves laborious simulation-optimization and limits the efficiency. The high-Q metamaterials with abrupt spectral change are even harder to reverse design on-demand. In this paper, we propose novel solutions for designing terahertz high-Q metamaterials based on deep learning, including the inverse design of structural parameters and the forward prediction of spectral responses. For the inverse design, we introduce the big data Visual Attention Network (VAN) model with a large model capability, and take additional parameter tuning for the key sensitive parameters and predict them individually, which can efficiently reduce errors and achieve highly accurate inverse design of structural parameters according to the target high-Q resonance responses. For the forward prediction, we develop the Electromagnetic Response Transformer (ERT) model to establish the complex mapping relations between the highly sensitive structural parameters and the abrupt spectra, and realize precise prediction of the high-Q resonance in terahertz spectra from given structural parameters. Our ERT model can be 4000 times faster than the conventional full wave simulations in computation time. Both models exhibit outstanding performance, and the accuracy is improved one or two orders higher compared to the traditional machine learning methods. Our work provides new avenues for the deep learning enabled design of terahertz high-Q metamaterials, which holds potential applications in various fields, such as terahertz communication, sensing, imaging, and functional devices.
{"title":"Deep learning enabled design of terahertz high-Q metamaterials","authors":"Shan Yin, Haotian Zhong, Wei Huang, Wentao Zhang","doi":"10.1016/j.optlastec.2024.111684","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111684","url":null,"abstract":"Metamaterials open up a new way to manipulate electromagnetic waves and realize various functional devices. Metamaterials with high-quality factor (Q) resonance responses are widely employed in sensing, detection, and other applications. Traditional design of metamaterials involves laborious simulation-optimization and limits the efficiency. The high-Q metamaterials with abrupt spectral change are even harder to reverse design on-demand. In this paper, we propose novel solutions for designing terahertz high-Q metamaterials based on deep learning, including the inverse design of structural parameters and the forward prediction of spectral responses. For the inverse design, we introduce the big data Visual Attention Network (VAN) model with a large model capability, and take additional parameter tuning for the key sensitive parameters and predict them individually, which can efficiently reduce errors and achieve highly accurate inverse design of structural parameters according to the target high-Q resonance responses. For the forward prediction, we develop the Electromagnetic Response Transformer (ERT) model to establish the complex mapping relations between the highly sensitive structural parameters and the abrupt spectra, and realize precise prediction of the high-Q resonance in terahertz spectra from given structural parameters. Our ERT model can be 4000 times faster than the conventional full wave simulations in computation time. Both models exhibit outstanding performance, and the accuracy is improved one or two orders higher compared to the traditional machine learning methods. Our work provides new avenues for the deep learning enabled design of terahertz high-Q metamaterials, which holds potential applications in various fields, such as terahertz communication, sensing, imaging, and functional devices.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04DOI: 10.1016/j.optlastec.2024.111735
Ze Li, Jianhua Wang, Suzhen Wang, Wen Zhang, Shuo Shan, Yanxi Yang
Single-shot three-dimensional (3D) measurement has always been the ultimate goal of fringe projection profilometry (FPP). Some studies have shown that deep learning outperforms traditional algorithm in analyzing single fringe pattern for complex scenarios. However, accurately phase unwrapping for a single wrapped phase map remains a significant challenge. In this paper, we propose a deep learning-based fringe projection profilometry. This method considers the geometric constraints of the measurement system. With the reference phase generated by the calibration parameters and appropriately designed intermediate variables based on physical models and prior knowledge, the proposed method is capable of recovering high-quality absolute phase from a single fringe pattern at the accuracy sufficiently high to rival traditional multi-frame algorithms. In addition, as far as FPP is concerned, the significance of the reference phase generated by the calibration parameters of the measurement system for deep learning-based single-frame phase unwrapping is experimentally demonstrated. Experiments on both static and dynamic scenarios show that the proposed method can achieves motion-artifact-free and high-resolution single-shot 3D measurements in various complex scenarios using only a single-frequency fringe projection.
{"title":"Single-shot 3D measurement via deep learning fringe projection profilometry with geometric constraints","authors":"Ze Li, Jianhua Wang, Suzhen Wang, Wen Zhang, Shuo Shan, Yanxi Yang","doi":"10.1016/j.optlastec.2024.111735","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111735","url":null,"abstract":"Single-shot three-dimensional (3D) measurement has always been the ultimate goal of fringe projection profilometry (FPP). Some studies have shown that deep learning outperforms traditional algorithm in analyzing single fringe pattern for complex scenarios. However, accurately phase unwrapping for a single wrapped phase map remains a significant challenge. In this paper, we propose a deep learning-based fringe projection profilometry. This method considers the geometric constraints of the measurement system. With the reference phase generated by the calibration parameters and appropriately designed intermediate variables based on physical models and prior knowledge, the proposed method is capable of recovering high-quality absolute phase from a single fringe pattern at the accuracy sufficiently high to rival traditional multi-frame algorithms. In addition, as far as FPP is concerned, the significance of the reference phase generated by the calibration parameters of the measurement system for deep learning-based single-frame phase unwrapping is experimentally demonstrated. Experiments on both static and dynamic scenarios show that the proposed method can achieves motion-artifact-free and high-resolution single-shot 3D measurements in various complex scenarios using only a single-frequency fringe projection.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04DOI: 10.1016/j.optlastec.2024.111715
Xiangyu Zhao, Hongyu Luo
Rare-earth-ion-doped fluoride fiber laser enabled by direct diode pumping provides a compact and robust platform for mid-infrared production, thereby serving a number of real-world applications. Nowadays, the power of such an architecture beyond 3 μm, however, has been clamped at < 1 W due to lack of readily available laser diode and/or efficient operation mechanism. In this work, we experimentally present efficient watt-level power output beyond 3 μm from an Er/Dy codoped fluoride fiber laser, clad-pumped by a cost-effective 974 nm diode, for the first time. In a free-running F-P scheme with an optimized output coupler reflectivity of 33 %, a maximum output power of 3.03 W at ∼3210 nm has been achieved with a slope efficiency of up to 19.1 % (with respect to the coupled pump), representing the first > 1 W diode-pumped rare-earth-ion-doped fiber laser beyond 3 µm with the highest efficiency. Then the numerical model, validated by our experimental data, has been built up, in which the previously ignored processes (i.e., ∼2.8 µm emission of Er and absorption of Dy) have been considered as an equivalent cross relaxation process, and confirmed probably to be the dominant role in determining efficient operation of this system. Using the model, the numerical optimization and performance prediction have been performed. Numerical comparison with the state-of-the-art Dy-doped fluoride fiber laser in this band based on tandem pumping approach indicates great potential of Er/Dy codoped system in high-power operation and its merits of compactness and high cost effectiveness as a promising alternative scheme.
通过直接二极管泵浦实现的稀土离子掺杂氟化物光纤激光器为中红外生产提供了一个紧凑而坚固的平台，从而服务于许多实际应用。然而，目前这种结构在 3 μm 以上的功率一直被限制在 1 W 二极管泵浦稀土离子掺杂光纤激光器在 3 µm 以上的最高效率。随后，我们建立了一个数值模型，并通过实验数据进行了验证。在该模型中，之前被忽略的过程（即 ∼2.8 µm 的 Er 发射和 Dy 吸收）被视为等效的交叉弛豫过程，并被证实可能是决定该系统高效运行的主要因素。利用该模型进行了数值优化和性能预测。与基于串联泵浦方法的该波段最先进的掺镝氟化物光纤激光器进行的数值比较表明，掺铒/掺镝系统在高功率运行方面具有巨大潜力，而且作为一种有前途的替代方案，它具有结构紧凑和成本效益高的优点。
{"title":"Efficient watt-level fluoride fiber laser beyond 3 μm enabled by direct diode pumping","authors":"Xiangyu Zhao, Hongyu Luo","doi":"10.1016/j.optlastec.2024.111715","DOIUrl":"https://doi.org/10.1016/j.optlastec.2024.111715","url":null,"abstract":"Rare-earth-ion-doped fluoride fiber laser enabled by direct diode pumping provides a compact and robust platform for mid-infrared production, thereby serving a number of real-world applications. Nowadays, the power of such an architecture beyond 3 μm, however, has been clamped at < 1 W due to lack of readily available laser diode and/or efficient operation mechanism. In this work, we experimentally present efficient watt-level power output beyond 3 μm from an Er/Dy codoped fluoride fiber laser, clad-pumped by a cost-effective 974 nm diode, for the first time. In a free-running F-P scheme with an optimized output coupler reflectivity of 33 %, a maximum output power of 3.03 W at ∼3210 nm has been achieved with a slope efficiency of up to 19.1 % (with respect to the coupled pump), representing the first > 1 W diode-pumped rare-earth-ion-doped fiber laser beyond 3 µm with the highest efficiency. Then the numerical model, validated by our experimental data, has been built up, in which the previously ignored processes (i.e., ∼2.8 µm emission of Er and absorption of Dy) have been considered as an equivalent cross relaxation process, and confirmed probably to be the dominant role in determining efficient operation of this system. Using the model, the numerical optimization and performance prediction have been performed. Numerical comparison with the state-of-the-art Dy-doped fluoride fiber laser in this band based on tandem pumping approach indicates great potential of Er/Dy codoped system in high-power operation and its merits of compactness and high cost effectiveness as a promising alternative scheme.","PeriodicalId":19597,"journal":{"name":"Optics & Laser Technology","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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