Pub Date : 2024-10-09DOI: 10.1016/j.infrared.2024.105578
Visible lasers based on blue laser diodes (LDs) pumped trivalent rare-earth ions doped crystal have recently attracted growing attention due to their advantages of high-efficiency, compact structure, and low cost, having wide applications in the fields of laser displays, biomedicine, material processing and so on. Pr:YLF lasers have been widely researched and further developed for the excellent spectral characteristics of Pr:YLF crystals. Specifically, LD-pumped continuous-wave (CW) Pr:YLF lasers have attained significant progress in lasing output performance, including output power scaling, emission wavelength expansion, and output mode diversification with the maturity of blue LDs. This paper mainly reviews the recent research progress on output performance improvement and provides insights into the further development trend of LD-pumped CW Pr:YLF lasers, aiming to provide a useful reference for the development of LD-pumped CW Pr:YLF lasers in the future.
{"title":"Recent advances for diode-pumped CW Pr:YLF lasers in power scaling at different wavelengths","authors":"","doi":"10.1016/j.infrared.2024.105578","DOIUrl":"10.1016/j.infrared.2024.105578","url":null,"abstract":"<div><div>Visible lasers based on blue laser diodes (LDs) pumped trivalent rare-earth ions doped crystal have recently attracted growing attention due to their advantages of high-efficiency, compact structure, and low cost, having wide applications in the fields of laser displays, biomedicine, material processing and so on. Pr:YLF lasers have been widely researched and further developed for the excellent spectral characteristics of Pr:YLF crystals. Specifically, LD-pumped continuous-wave (CW) Pr:YLF lasers have attained significant progress in lasing output performance, including output power scaling, emission wavelength expansion, and output mode diversification with the maturity of blue LDs. This paper mainly reviews the recent research progress on output performance improvement and provides insights into the further development trend of LD-pumped CW Pr:YLF lasers, aiming to provide a useful reference for the development of LD-pumped CW Pr:YLF lasers in the future.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-09DOI: 10.1016/j.infrared.2024.105588
This study presents the synthesis of environmentally benign, single-layered spectrally selective Ag/NiO nanocoating absorbers using a green synthesis method. Various characterization techniques, including Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), were used to examine the effects of plasmonic Ag concentration on the structural, chemical composition, and surface morphology of the nanocomposites. The optical properties of the deposited nanocoatings were investigated using a UV–Vis-NIR spectrophotometer in the solar spectrum region (300–2500 nm) and an FT-IR spectrophotometer in the infrared wavelength region (3000–20,000 nm). XRD results confirmed the coexistence of a face-centered cubic phase of Ag and NiO in the Ag/NiO nanocermet thin films. SEM and TEM topography revealed uniformly distributed nanosphere NiO thin films and cubic Ag metal with better dispersibility and crystallization. The RBS spectrum of the samples showed a homogeneous distribution of Ni, Ag, and O atoms throughout the coatings. Ag/NiO nanocoatings deposited with 8 wt% Ag content exhibited excellent solar absorptance (α) = 0.95 and thermal emittance of (ɛ) of 0.08. This enhancement is primarily attributed to the localized surface plasmon resonance (LSPR) effect associated with the embedded Ag nanoparticles, which facilitates more effective utilization of light.
{"title":"Single layered Ag/NiO plasmonic nanocoatings: A new green synthesis method for selective solar absorber","authors":"","doi":"10.1016/j.infrared.2024.105588","DOIUrl":"10.1016/j.infrared.2024.105588","url":null,"abstract":"<div><div>This study presents the synthesis of environmentally benign, single-layered spectrally selective Ag/NiO nanocoating absorbers using a green synthesis method. Various characterization techniques, including Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), were used to examine the effects of plasmonic Ag concentration on the structural, chemical composition, and surface morphology of the nanocomposites. The optical properties of the deposited nanocoatings were investigated using a UV–Vis-NIR spectrophotometer in the solar spectrum region (300–2500 nm) and an FT-IR spectrophotometer in the infrared wavelength region (3000–20,000 nm). XRD results confirmed the coexistence of a face-centered cubic phase of Ag and NiO in the Ag/NiO nanocermet thin films. SEM and TEM topography revealed uniformly distributed nanosphere NiO thin films and cubic Ag metal with better dispersibility and crystallization. The RBS spectrum of the samples showed a homogeneous distribution of Ni, Ag, and O atoms throughout the coatings. Ag/NiO nanocoatings deposited with 8 wt% Ag content exhibited excellent solar absorptance (α) = 0.95 and thermal emittance of (ɛ) of 0.08. This enhancement is primarily attributed to the localized surface plasmon resonance (LSPR) effect associated with the embedded Ag nanoparticles, which facilitates more effective utilization of light.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-09DOI: 10.1016/j.infrared.2024.105586
Research of materials’ optical properties is critical for further development and manufacturing of optical products. While recently, single crystals and two-phase ceramics of the AgCl0.25Br0.75 – AgI system have been developed by the authors. This work is focused on studying the transmission ranges, refractive index dispersion, optical losses, and photoresistance of materials in the AgCl0.25Br0.75 – AgI system, as well as comparing the properties of single-crystals and ceramics. The materials are transparent in the visible and IR regions from 0.49 to 54 um, as well as in the terahertz (far IR and millimeter regions) of 300–1500 um (0.3–1.0 THz). For all compositions, the refractive index in the IR varied from 2.107 to 2.436. The materials’ absorption coefficients were (0.06–6.67) ∙ 10-4 in the middle IR, which is lower compared to other halide materials known and indicates low optical loss. Finally, both single-crystals and two-phase ceramics showed a trend towards an increase in photoresistance with a rise of the AgI content in the AgCl0.25Br0.75 solid solution. After UV irradiation, the materials showed a decrease in transmission in the visible and middle IR (to 10 µm) with negligible loss at a wavelength of 10 µm or more. For a single crystal and two samples of ceramics with a composition of 20 mol. % AgI in AgCl0.25Br0.75, a comparison of properties was conducted in this study. Based on the comparison results, close but not identical values of the refractive indices, an increase in the absorption coefficient for ceramic materials, and a low photoresistance of the sample obtained from the mechanical mixture were revealed. The last two characteristics are associated with the high heterogeneity of two-phase ceramics based on a mechanical mixture, which leads to a deterioration in functional properties. These results prove high prospects for the use of these materials in fiber optics and photonics for medical technologies, thermography, and optoelectronics.
{"title":"Optical properties of crystals and two-phase ceramics of the AgCl0.25Br0.75 – AgI system","authors":"","doi":"10.1016/j.infrared.2024.105586","DOIUrl":"10.1016/j.infrared.2024.105586","url":null,"abstract":"<div><div>Research of materials’ optical properties is critical for further development and manufacturing of optical products. While recently, single crystals and two-phase ceramics of the AgCl<sub>0.25</sub>Br<sub>0.75</sub> – AgI system have been developed by the authors. This work is focused on studying the transmission ranges, refractive index dispersion, optical losses, and photoresistance of materials in the AgCl<sub>0.25</sub>Br<sub>0.75</sub> – AgI system, as well as comparing the properties of single-crystals and ceramics. The materials are transparent in the visible and IR regions from 0.49 to 54 um, as well as in the terahertz (far IR and millimeter regions) of 300–1500 um (0.3–1.0 THz). For all compositions, the refractive index in the IR varied from 2.107 to 2.436. The materials’ absorption coefficients were (0.06–6.67) ∙ 10<sup>-4</sup> in the middle IR, which is lower compared to other halide materials known and indicates low optical loss. Finally, both single-crystals and two-phase ceramics showed a trend towards an increase in photoresistance with a rise of the AgI content in the AgCl<sub>0.25</sub>Br<sub>0.75</sub> solid solution. After UV irradiation, the materials showed a decrease in transmission in the visible and middle IR (to 10 µm) with negligible loss at a wavelength of 10 µm or more. For a single crystal and two samples of ceramics with a composition of 20 mol. % AgI in AgCl<sub>0.25</sub>Br<sub>0.75</sub>, a comparison of properties was conducted in this study. Based on the comparison results, close but not identical values of the refractive indices, an increase in the absorption coefficient for ceramic materials, and a low photoresistance of the sample obtained from the mechanical mixture were revealed. The last two characteristics are associated with the high heterogeneity of two-phase ceramics based on a mechanical mixture, which leads to a deterioration in functional properties. These results prove high prospects for the use of these materials in fiber optics and photonics for medical technologies, thermography, and optoelectronics.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-09DOI: 10.1016/j.infrared.2024.105589
We show that infrared detectors frequently exhibit non-Gaussian spatial noise, which makes it difficult to compare their performance. The power-law-like behavior we show can be very detrimental to certain detection missions, hence the need to characterize this noise. We demonstrate that a simple mixture of Gaussian and Student processes corresponds to the observed example, and that the parameter determination procedure described here reaches its theoretical limit.
{"title":"Experience-based noise model of infrared detectors for system dimensioning and simulation","authors":"","doi":"10.1016/j.infrared.2024.105589","DOIUrl":"10.1016/j.infrared.2024.105589","url":null,"abstract":"<div><div>We show that infrared detectors frequently exhibit non-Gaussian spatial noise, which makes it difficult to compare their performance. The power-law-like behavior we show can be very detrimental to certain detection missions, hence the need to characterize this noise. We demonstrate that a simple mixture of Gaussian and Student processes corresponds to the observed example, and that the parameter determination procedure described here reaches its theoretical limit.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-09DOI: 10.1016/j.infrared.2024.105585
This study proposes a novel diagnostic approach for target ablation to comprehensively elucidate the physical mechanisms of laser ablation in aluminium alloys and stainless steel, precisely measure sample temperatures, and predict the ablation state. The method utilizes a spatially weighted emissivity model in conjunction with multispectral thermometry techniques to analyze spatial variations in temperature and emissivity distributions, facilitating the evaluation of target ablation status. Through a series of experiments, temperature data obtained using an enhanced weighted radiative spectral inversion technique were compared with temperatures recorded by thermal imaging cameras, confirming the effectiveness and accuracy of the weighted radiative spectral inversion method in multispectral thermometry. Additionally, a detailed examination of laser ablation in aluminium alloys and stainless steel was conducted to elucidate the underlying damage mechanisms. This refined approach establishes a solid groundwork for further investigation into the characteristics and dynamic Evolution of laser-damaged regions.
{"title":"A composite laser ablation diagnosis method based on multiple spectroscopic and imaging analyses","authors":"","doi":"10.1016/j.infrared.2024.105585","DOIUrl":"10.1016/j.infrared.2024.105585","url":null,"abstract":"<div><div>This study proposes a novel diagnostic approach for target ablation to comprehensively elucidate the physical mechanisms of laser ablation in aluminium alloys and stainless steel, precisely measure sample temperatures, and predict the ablation state. The method utilizes a spatially weighted emissivity model in conjunction with multispectral thermometry techniques to analyze spatial variations in temperature and emissivity distributions, facilitating the evaluation of target ablation status. Through a series of experiments, temperature data obtained using an enhanced weighted radiative spectral inversion technique were compared with temperatures recorded by thermal imaging cameras, confirming the effectiveness and accuracy of the weighted radiative spectral inversion method in multispectral thermometry. Additionally, a detailed examination of laser ablation in aluminium alloys and stainless steel was conducted to elucidate the underlying damage mechanisms. This refined approach establishes a solid groundwork for further investigation into the characteristics and dynamic Evolution of laser-damaged regions.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-05DOI: 10.1016/j.infrared.2024.105583
The technology for sex identification in ducklings can contribute to increased revenue and cost savings in modern duck farming. However, traditional manual identification techniques require high skill levels and involve significant labor intensity. In this study, a non-destructive, user-friendly, and efficient duckling sex identification technique was proposed using near-infrared spectroscopy and deep learning algorithms. Spectral data from 600 groups of newly hatched ducklings were collected. These data were divided into training, testing, and validation sets in a ratio of 7:2:1. The raw spectral data was preprocessed using the Savitzky-Golay convolution derivative method, which was employed for subsequent spectral feature wavelength extraction and modeling. The characteristic wavelengths were extracted using competitive adaptive reweighted sampling (CARS), successive projections algorithm (SPA), and uninformative variable elimination combined with SPA (UVE-SPA). Conventional machine learning methods − support vector machine (SVM) and different deep learning models, including multilayer perceptron (MLP), mobile network version 2 (MobileNetV2), and residual neural network (ResNet), were studied and compared. The experiment showed that deep learning algorithms outperform traditional spectral analysis models in terms of classification performance. Furthermore, conducting feature wavelength extraction before constructing the classification model could reduce the model’s testing time and even improve its classification performance. Finally, the four models with better classification performance were validated using a validation set, and the combination of MobileNetV2 model UVE-SPA was selected as the optimized model for ducklings’ gender determination, with a classification accuracy of 98.3 % and an average validation time of 1.1 ms. In summary, the detection model established using near-infrared spectroscopy and MobileNetV2 can achieve non-destructive identification of the gender of ducklings. The findings can provide a preliminary research foundation and technical support for the subsequent design of related online intelligent detection systems.
{"title":"Non-destructive detection of male and female information in ducklings based on near-infrared spectral wavelength selection and deep learning","authors":"","doi":"10.1016/j.infrared.2024.105583","DOIUrl":"10.1016/j.infrared.2024.105583","url":null,"abstract":"<div><div>The technology for sex identification in ducklings can contribute to increased revenue and cost savings in modern duck farming. However, traditional manual identification techniques require high skill levels and involve significant labor intensity. In this study, a non-destructive, user-friendly, and efficient duckling sex identification technique was proposed using near-infrared spectroscopy and deep learning algorithms. Spectral data from 600 groups of newly hatched ducklings were collected. These data were divided into training, testing, and validation sets in a ratio of 7:2:1. The raw spectral data was preprocessed using the Savitzky-Golay convolution derivative method, which was employed for subsequent spectral feature wavelength extraction and modeling. The characteristic wavelengths were extracted using competitive adaptive reweighted sampling (CARS), successive projections algorithm (SPA), and uninformative variable elimination combined with SPA (UVE-SPA). Conventional machine learning methods − support vector machine (SVM) and different deep learning models, including multilayer perceptron (MLP), mobile network version 2 (MobileNetV2), and residual neural network (ResNet), were studied and compared. The experiment showed that deep learning algorithms outperform traditional spectral analysis models in terms of classification performance. Furthermore, conducting feature wavelength extraction before constructing the classification model could reduce the model’s testing time and even improve its classification performance. Finally, the four models with better classification performance were validated using a validation set, and the combination of MobileNetV2 model UVE-SPA was selected as the optimized model for ducklings’ gender determination, with a classification accuracy of 98.3 % and an average validation time of 1.1 ms. In summary, the detection model established using near-infrared spectroscopy and MobileNetV2 can achieve non-destructive identification of the gender of ducklings. The findings can provide a preliminary research foundation and technical support for the subsequent design of related online intelligent detection systems.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-05DOI: 10.1016/j.infrared.2024.105571
Transparent Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics (BSEr1TmxGCs) with variable Tm3+ concentration were prepared through melt quench process followed by reheat treatment at 450 °C/1h. They were characterized through differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) Raman spectroscopy, near infrared (NIR) emission and luminescence decay. The formation of CaF2 nanocrystallites against oxyfluoroborosilicate glassy phase was confirmed by scanning electron microscopic (SEM) and hi-resolution transmission electron microscopic (HRTEM) studies. The NIR emission properties were investigated at 460 nm diode laser pumping. The applicability of BSEr1TmxGCs were examined by evaluating effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe × Δλeff), figure of merit (σe × τR) and quantum efficiency (ηQE). The energy transfer efficiency (ηET), rate of energy transfer (WET) between Er3+ and Tm3+ and the rate of non-radiative transitions (WNR) were also calculated. The comparative NIR emission performance suggests that the BSEr1Tm1GC has proficiency for 1530 nm broadband fiber lasers and optical amplifiers in short wavelength and conventional wavelength (S + C) band communication window.
{"title":"Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics for fiber laser applications","authors":"","doi":"10.1016/j.infrared.2024.105571","DOIUrl":"10.1016/j.infrared.2024.105571","url":null,"abstract":"<div><div>Transparent Er<sup>3+</sup>/Tm<sup>3+</sup> codoped CaF<sub>2</sub> based oxyfluoroborosilicate glass-ceramics (BSEr1Tm<em>x</em>GCs) with variable Tm<sup>3+</sup> concentration were prepared through melt quench process followed by reheat treatment at 450 °C/1h. They were characterized through differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) Raman spectroscopy, near infrared (NIR) emission and luminescence decay. The formation of CaF<sub>2</sub> nanocrystallites against oxyfluoroborosilicate glassy phase was confirmed by scanning electron microscopic (SEM) and hi-resolution transmission electron microscopic (HRTEM) studies. The NIR emission properties were investigated at 460 nm diode laser pumping. The applicability of BSEr1Tm<em>x</em>GCs were examined by evaluating effective bandwidth (Δλ<sub>eff</sub>), stimulated emission cross-section (σ<sub>e</sub>), gain bandwidth (σ<sub>e</sub> × Δλ<sub>eff</sub>), figure of merit (σ<sub>e</sub> × τ<sub>R</sub>) and quantum efficiency (η<sub>QE</sub>). The energy transfer efficiency (η<sub>ET</sub>), rate of energy transfer (W<sub>ET</sub>) between Er<sup>3+</sup> and Tm<sup>3+</sup> and the rate of non-radiative transitions (W<sub>NR</sub>) were also calculated. The comparative NIR emission performance suggests that the BSEr1Tm1GC has proficiency for 1530 nm broadband fiber lasers and optical amplifiers in short wavelength and conventional wavelength (S + C) band communication window.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-05DOI: 10.1016/j.infrared.2024.105569
Recently, Convolutional Transformer-based models have become popular in hyperspectral image (HSI) classification tasks and gained competitive classification performance. However, some Convolutional Transformer-based models fail to effectively mine the global correlations of coarse-grained and fine-grained features, which is adverse to recognizing the refined scale variation information of land-cover. The combination of convolution operations and multihead self-attention mechanisms also increases the computational cost, leading to low classification efficiency. In addition, shallow spectral–spatial features are directly input into the encoder, which inevitably incurs redundant spectral information. Therefore, this paper proposes an efficient enhancement Transformer network (E2TNet) for HSI classification. Specifically, this paper first designs a spectral–spatial feature fusion module to extract spectral and spatial features from HSI cubes and fuse them. Second, considering that redundant spectral information has a negative impact on classification performance, this paper designs a spectral–spatial feature weighted module to improve the feature representation of critical spectral information. Finally, to explore the global correlations of coarse-grained and fine-grained features and improve classification efficiency, an efficient multigranularity information fusion module is embedded in the encoder of E2TNet. The experiment is conducted on four benchmark hyperspectral datasets, and the experimental results demonstrate that the proposed E2TNet is better than several Convolutional Transformer-based classification models in terms of classification accuracy and classification efficiency.
{"title":"E2TNet: Efficient enhancement Transformer network for hyperspectral image classification","authors":"","doi":"10.1016/j.infrared.2024.105569","DOIUrl":"10.1016/j.infrared.2024.105569","url":null,"abstract":"<div><div>Recently, Convolutional Transformer-based models have become popular in hyperspectral image (HSI) classification tasks and gained competitive classification performance. However, some Convolutional Transformer-based models fail to effectively mine the global correlations of coarse-grained and fine-grained features, which is adverse to recognizing the refined scale variation information of land-cover. The combination of convolution operations and multihead self-attention mechanisms also increases the computational cost, leading to low classification efficiency. In addition, shallow spectral–spatial features are directly input into the encoder, which inevitably incurs redundant spectral information. Therefore, this paper proposes an efficient enhancement Transformer network (E2TNet) for HSI classification. Specifically, this paper first designs a spectral–spatial feature fusion module to extract spectral and spatial features from HSI cubes and fuse them. Second, considering that redundant spectral information has a negative impact on classification performance, this paper designs a spectral–spatial feature weighted module to improve the feature representation of critical spectral information. Finally, to explore the global correlations of coarse-grained and fine-grained features and improve classification efficiency, an efficient multigranularity information fusion module is embedded in the encoder of E2TNet. The experiment is conducted on four benchmark hyperspectral datasets, and the experimental results demonstrate that the proposed E2TNet is better than several Convolutional Transformer-based classification models in terms of classification accuracy and classification efficiency.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-04DOI: 10.1016/j.infrared.2024.105572
Ultrafast fiber lasers based on nonlinear polarization rotation can generate femtosecond pulses with different pulse durations and high peak powers, which are powerful tools for engineering applications and scientific research. However, achieving a precise and repeatable polarization state for generating the ultrashort pulses with the shortest pulse duration remains a significant challenge. In this paper, we extend the use of recurrent neural networks and adaptive optimization algorithms, specifically designed to optimize repetitive processes in optical systems, to facilitate intelligent search and control aimed at achieving the minimum pulse duration within a mode-locked fiber laser cavity. Our multi-algorithm-based intelligent system can fully simulate and optimize the processes involved in hands-on experiments. Our intelligent system identified a mode-locked fiber laser with the shortest pulse duration of 465 fs, which was experimentally verified. The proposed intelligent algorithm not only identifies the shortest pulse but also holds significant potential for selecting related laser characteristic parameters. We believe this work opens up a novel avenue for exploration and optimization in mode-locked lasers and the intelligent laser can find practical applications in engineering and scientific research.
{"title":"Intelligent controllable ultrafast fiber laser via deep learning and adaptive optimization algorithm","authors":"","doi":"10.1016/j.infrared.2024.105572","DOIUrl":"10.1016/j.infrared.2024.105572","url":null,"abstract":"<div><div>Ultrafast fiber lasers based on nonlinear polarization rotation can generate femtosecond pulses with different pulse durations and high peak powers, which are powerful tools for engineering applications and scientific research. However, achieving a precise and repeatable polarization state for generating the ultrashort pulses with the shortest pulse duration remains a significant challenge. In this paper, we extend the use of recurrent neural networks and adaptive optimization algorithms, specifically designed to optimize repetitive processes in optical systems, to facilitate intelligent search and control aimed at achieving the minimum pulse duration within a mode-locked fiber laser cavity. Our multi-algorithm-based intelligent system can fully simulate and optimize the processes involved in hands-on experiments. Our intelligent system identified a mode-locked fiber laser with the shortest pulse duration of 465 fs, which was experimentally verified. The proposed intelligent algorithm not only identifies the shortest pulse but also holds significant potential for selecting related laser characteristic parameters. We believe this work opens up a novel avenue for exploration and optimization in mode-locked lasers and the intelligent laser can find practical applications in engineering and scientific research.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-04DOI: 10.1016/j.infrared.2024.105577
A high-power diode-pumped 2.09 μm Tm,Ho:YAG laser oscillator with multi-regime operation is demonstrated. In the continuous-wave (CW) regime, it delivers 44.68 W output power with M2 = 3.47, yielding a record-high brightness of 87.57 MW/cm2·sr. In the Q-switched mode, stable laser performance across pulse repetition frequencies (PRFs) from 1 kHz to 4 kHz is achieved. At a PRF of 1 kHz, single pulse energy reaches 22.85 mJ with a pulse width of 443.4 ns and M2 = 3.50. In the quasi-continuous-wave (QCW) operation, a pulse energy of 31.85 mJ is obtained at 200 Hz with a 370 μs pulse width and M2 = 4.49. These pulse energies are the highest reported to date for Tm-Ho co-doped laser oscillators at high PRF. This also marks the first demonstration of a versatile 2 μm laser that can operate at room temperature while delivering high-energy, high-repetition-rate pulses in both nanosecond and microsecond durations within a single device, making it highly appealing for scientific and industrial applications.
{"title":"High power continuous-wave, Q-switched, and quasi-continuous-wave operation of a diode-pumped Tm,Ho:YAG laser oscillator at 2.09 μm","authors":"","doi":"10.1016/j.infrared.2024.105577","DOIUrl":"10.1016/j.infrared.2024.105577","url":null,"abstract":"<div><div>A high-power diode-pumped 2.09 μm Tm,Ho:YAG laser oscillator with multi-regime operation is demonstrated. In the continuous-wave (CW) regime, it delivers 44.68 W output power with <em>M<sup>2</sup></em> = 3.47, yielding a record-high brightness of 87.57 MW/cm<sup>2</sup>·sr. In the Q-switched mode, stable laser performance across pulse repetition frequencies (PRFs) from 1 kHz to 4 kHz is achieved. At a PRF of 1 kHz, single pulse energy reaches 22.85 mJ with a pulse width of 443.4 ns and <em>M<sup>2</sup></em> = 3.50. In the quasi-continuous-wave (QCW) operation, a pulse energy of 31.85 mJ is obtained at 200 Hz with a 370 μs pulse width and <em>M<sup>2</sup></em> = 4.49. These pulse energies are the highest reported to date for Tm-Ho co-doped laser oscillators at high PRF. This also marks the first demonstration of a versatile 2 μm laser that can operate at room temperature while delivering high-energy, high-repetition-rate pulses in both nanosecond and microsecond durations within a single device, making it highly appealing for scientific and industrial applications.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
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