Pub Date : 2025-01-29DOI: 10.1016/j.optlastec.2025.112531
Chun-Lin Wu , Hong Zheng , Xiao-Wen Hu , Ming-Ming Yang , Yu Zhang , Qi-Geng Yan , Li Tan , Zi-Long Song , Bao-Lai Liang , Xiao-Hui Zhao , Wei Dang , Xiao-Li Li
Exciton photoluminescence (PL) is a powerful method for investigating the optoelectronic properties of transition metal dichalcogenides (TMDs), where defects are crucial in exciton emission. We explored the exciton emissions at the boundary between single-layer MoS2 (SLM) and bilayer MoS2 (BLM) using temperature-dependent PL spectra from 7 K to 300 K, uncovering the impact of localized states. The clearest indication is that the overall PL intensity at the boundary was weaker than in SLM and BLM. Moreover, at the boundary, the temperature-induced redshift of the A exciton was significantly diminished because of the low-energy tail effect of localized states, and a slight redshift of the I exciton was detected due to nonradiative recombination of these states. The intensities of the A, B, and I excitons were much lower at the boundary, implying the involvement of localized states in charge recombination. The full width at half maximum (FWHM) of both the A and I excitons grew more quickly with temperature at the boundary, thanks to the enhanced lattice vibration related to the localized states. This study not only enriches our knowledge of exciton emission but also offers opportunities for defect engineering in two-dimensional layered materials.
{"title":"Study on exciton properties at single-layer and bilayer MoS2 boundary","authors":"Chun-Lin Wu , Hong Zheng , Xiao-Wen Hu , Ming-Ming Yang , Yu Zhang , Qi-Geng Yan , Li Tan , Zi-Long Song , Bao-Lai Liang , Xiao-Hui Zhao , Wei Dang , Xiao-Li Li","doi":"10.1016/j.optlastec.2025.112531","DOIUrl":"10.1016/j.optlastec.2025.112531","url":null,"abstract":"<div><div>Exciton photoluminescence (PL) is a powerful method for investigating the optoelectronic properties of transition metal dichalcogenides (TMDs), where defects are crucial in exciton emission. We explored the exciton emissions at the boundary between single-layer MoS<sub>2</sub> (SLM) and bilayer MoS<sub>2</sub> (BLM) using temperature-dependent PL spectra from 7 K to 300 K, uncovering the impact of localized states. The clearest indication is that the overall PL intensity at the boundary was weaker than in SLM and BLM. Moreover, at the boundary, the temperature-induced redshift of the A exciton was significantly diminished because of the low-energy tail effect of localized states, and a slight redshift of the I exciton was detected due to nonradiative recombination of these states. The intensities of the A, B, and I excitons were much lower at the boundary, implying the involvement of localized states in charge recombination. The full width at half maximum (FWHM) of both the A and I excitons grew more quickly with temperature at the boundary, thanks to the enhanced lattice vibration related to the localized states. This study not only enriches our knowledge of exciton emission but also offers opportunities for defect engineering in two-dimensional layered materials.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112531"},"PeriodicalIF":4.6,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-29DOI: 10.1016/j.optlastec.2025.112543
Shaode Li , Wei He , Zhehai Zhou , Lihang Xu , Chao Wang
Step-index fiber Bragg gratings (SI-FBGs) are increasingly recognized for their potential applications in optical communications, sensing, and laser systems. This study introduces three novel types of heterogeneous step-index fiber Bragg gratings (Hetero-SI-FBGs), fabricated using the femtosecond laser point-by-point technique. To the best of our knowledge, this work represents the first demonstration of fabricating 3 mm femtosecond gratings in heterogeneous step-index (Hetero-SI) fibers. When compared with homogeneous step-index fiber Bragg gratings (Homo-SI-FBGs) produced via the traditional ultraviolet-laser phase-mask technique, the developed Hetero-SI-FBGs offer an increased number of wavelength output channels, enhanced optical signal-to-noise ratio (OSNR), and expanded multifunctional optical properties. The OSNR for two distinct wavelength channels in the reflection spectrum measured 22.19 dB and 20.67 dB, respectively. Furthermore, the femtosecond laser technique employed here exhibits greater flexibility, reduced fiber damage, and enhanced potential for multifunctional integration than the ultraviolet-laser phase-mask technology. To address current research limitations in Hetero-SI fibers, the Hetero-SI-FBGs were implemented as wavelength reflection filters in random fiber lasers (RFLs), facilitating stable random laser with reduced frequency noise. This advancement heralds a new era for SI-FBGs in multi-channel laser systems and underscores their promising capabilities in fiber sensing and wavelength-division multiplexing.
{"title":"A heterogeneous step-index fiber Bragg grating fabricated by femtosecond laser point-by-point technique for laser generation","authors":"Shaode Li , Wei He , Zhehai Zhou , Lihang Xu , Chao Wang","doi":"10.1016/j.optlastec.2025.112543","DOIUrl":"10.1016/j.optlastec.2025.112543","url":null,"abstract":"<div><div>Step-index fiber Bragg gratings (SI-FBGs) are increasingly recognized for their potential applications in optical communications, sensing, and laser systems. This study introduces three novel types of heterogeneous step-index fiber Bragg gratings (Hetero-SI-FBGs), fabricated using the femtosecond laser point-by-point technique. To the best of our knowledge, this work represents the first demonstration of fabricating 3 mm femtosecond gratings in heterogeneous step-index (Hetero-SI) fibers. When compared with homogeneous step-index fiber Bragg gratings (Homo-SI-FBGs) produced via the traditional ultraviolet-laser phase-mask technique, the developed Hetero-SI-FBGs offer an increased number of wavelength output channels, enhanced optical signal-to-noise ratio (OSNR), and expanded multifunctional optical properties. The OSNR for two distinct wavelength channels in the reflection spectrum measured 22.19 dB and 20.67 dB, respectively. Furthermore, the femtosecond laser technique employed here exhibits greater flexibility, reduced fiber damage, and enhanced potential for multifunctional integration than the ultraviolet-laser phase-mask technology. To address current research limitations in Hetero-SI fibers, the Hetero-SI-FBGs were implemented as wavelength reflection filters in random fiber lasers (RFLs), facilitating stable random laser with reduced frequency noise. This advancement heralds a new era for SI-FBGs in multi-channel laser systems and underscores their promising capabilities in fiber sensing and wavelength-division multiplexing.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112543"},"PeriodicalIF":4.6,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-29DOI: 10.1016/j.optlastec.2025.112518
Jun Chen , Xiaotian Li , Yuqi Sun , Jirigalantu , Ci Sun , Shuo Yu , Yubo Li , Qihang Chu , Bayanheshig
A broadband imaging polarimeter without linear polarizers (BIPWLP) based on channeled polarimetry is proposed. The proposed polarimeter applies two polarization grating pairs to spatially shear light. The second polarization grating pair completely separates the light of two diffraction orders. By changing one beam of the diffracted light to linearly polarized, BIPWLP obtains the interference patterns of linearly and circularly polarized light, which can preserve the polarization interference terms without linear polarizers oriented at 45° and then doubles throughput. The principle of BIPWLP is derived in detail. A design example for the wavelength range of 400−700 nm is presented. The numerical simulation results show that the parameter reconstruction of BIPWLP is highly accurate. The maximum root-mean-square error of four Stokes parameters is 0.0187 for various uniformly polarized image incidence cases. It is shown that BIPWLP can detect space-variant polarization. In addition, BIPWLP allows snapshots, has no moving parts, is easy to assemble, and has inherent image registration.
{"title":"Broadband snapshot imaging polarimeter for complete Stokes parameter measurement without linear polarizers","authors":"Jun Chen , Xiaotian Li , Yuqi Sun , Jirigalantu , Ci Sun , Shuo Yu , Yubo Li , Qihang Chu , Bayanheshig","doi":"10.1016/j.optlastec.2025.112518","DOIUrl":"10.1016/j.optlastec.2025.112518","url":null,"abstract":"<div><div>A broadband imaging polarimeter without linear polarizers (BIPWLP) based on channeled polarimetry is proposed. The proposed polarimeter applies two polarization grating pairs to spatially shear light. The second polarization grating pair completely separates the light of two diffraction orders. By changing one beam of the diffracted light to linearly polarized, BIPWLP obtains the interference patterns of linearly and circularly polarized light, which can preserve the polarization interference terms without linear polarizers oriented at 45° and then doubles throughput. The principle of BIPWLP is derived in detail. A design example for the wavelength range of 400−700 nm is presented. The numerical simulation results show that the parameter reconstruction of BIPWLP is highly accurate. The maximum root-mean-square error of four Stokes parameters is 0.0187 for various uniformly polarized image incidence cases. It is shown that BIPWLP can detect space-variant polarization. In addition, BIPWLP allows snapshots, has no moving parts, is easy to assemble, and has inherent image registration.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112518"},"PeriodicalIF":4.6,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optlastec.2025.112530
Jing Wang , Zhaozhong Meng , Yuan Wan
Advancements in directional emission and partial coherence of light sources offer significant potential applications in optical communication, light detection and ranging, and optical imaging. Our study introduces a conical structure, that renders random laser emission directional, with energy primarily concentrated between −5 degrees and 5 degrees. Furthermore, the strong scattering and local surface plasmon resonance of gold nanoparticles enhance the random laser’s performance, resulting in a low threshold and high brightness. The low spatial coherence of the random laser effectively inhibits speckle formation, while its directional emission improves imaging clarity. These two complementary advantages result in the contrast-to-noise ratio of image as high as 16.74. Finally, we demonstrate the proposed random laser’s advantages in biological imaging by imaging a mouse tail section specimen. This research presents a novel light source scheme for applications in optical communication, optical imaging and damage detection.
{"title":"Directional emission random lasers based on conical structure for micro-imaging","authors":"Jing Wang , Zhaozhong Meng , Yuan Wan","doi":"10.1016/j.optlastec.2025.112530","DOIUrl":"10.1016/j.optlastec.2025.112530","url":null,"abstract":"<div><div>Advancements in directional emission and partial coherence of light sources offer significant potential applications in optical communication, light detection and ranging, and optical imaging. Our study introduces a conical structure, that renders random laser emission directional, with energy primarily concentrated between −5 degrees and 5 degrees. Furthermore, the strong scattering and local surface plasmon resonance of gold nanoparticles enhance the random laser’s performance, resulting in a low threshold and high brightness. The low spatial coherence of the random laser effectively inhibits speckle formation, while its directional emission improves imaging clarity. These two complementary advantages result in the contrast-to-noise ratio of image as high as 16.74. Finally, we demonstrate the proposed random laser’s advantages in biological imaging by imaging a mouse tail section specimen. This research presents a novel light source scheme for applications in optical communication, optical imaging and damage detection.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112530"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optlastec.2025.112511
Haolin Yang , Sailing He
Here, we report a passively Q-switched Tm laser at 1720 nm. The Q-switching behavior originates from a piece of Tm-doped fiber. Tm-doped fiber has a broad absorption spectrum covering 1.7 μm waveband, which can be used as a fiber-type saturable absorber for 1.7 μm pulsed lasers. In comparison with the typical Q-switching system in which the gain fiber has a different rare-earth doping from the fiber-type saturable absorber, the same rare-earth doping in the gain fiber and the saturable absorber cannot support the effective Q-switching operation. To initiate the pulsing operation in this Tm-Tm laser system, we introduce a mismatch of mode-field area between the gain fiber and the fiber-type saturable absorber. By using ∼50 cm Tm-doped fibers as the saturable absorber, the passive Q-switching 1720 nm laser is realized and produces 340 mW output power with a nanosecond pulse width (400 ns ∼422 ns). After investigating the Q-switching pulses, it is found that the evolution trend of the pulses with the pump power is not consistent with the typical passive Q-switching lasers. In order to understand this unusual Q-switching behavior, we establish a rate equation model that is coupled with the mismatch of mode-field area to give a comprehensive understanding. From the numerical simulation, a new Q-switching laser cavity consisting of dual laser resonance is proposed to guide how to realize a passive Q-switching 1.7 μm laser with a higher output power.
{"title":"340 mW nanosecond compact 1.7 μm passively Q-switched laser based on a fiber-type saturable absorber with mismatch of mode-field area","authors":"Haolin Yang , Sailing He","doi":"10.1016/j.optlastec.2025.112511","DOIUrl":"10.1016/j.optlastec.2025.112511","url":null,"abstract":"<div><div>Here, we report a passively Q-switched Tm laser at 1720 nm. The Q-switching behavior originates from a piece of Tm-doped fiber. Tm-doped fiber has a broad absorption spectrum covering 1.7 μm waveband, which can be used as a fiber-type saturable absorber for 1.7 μm pulsed lasers. In comparison with the typical Q-switching system in which the gain fiber has a different rare-earth doping from the fiber-type saturable absorber, the same rare-earth doping in the gain fiber and the saturable absorber cannot support the effective Q-switching operation. To initiate the pulsing operation in this Tm-Tm laser system, we introduce a mismatch of mode-field area between the gain fiber and the fiber-type saturable absorber. By using ∼50 cm Tm-doped fibers as the saturable absorber, the passive Q-switching 1720 nm laser is realized and produces 340 mW output power with a nanosecond pulse width (400 ns ∼422 ns). After investigating the Q-switching pulses, it is found that the evolution trend of the pulses with the pump power is not consistent with the typical passive Q-switching lasers. In order to understand this unusual Q-switching behavior, we establish a rate equation model that is coupled with the mismatch of mode-field area to give a comprehensive understanding. From the numerical simulation, a new Q-switching laser cavity consisting of dual laser resonance is proposed to guide how to realize a passive Q-switching 1.7 μm laser with a higher output power.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112511"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optlastec.2025.112541
Liyun Hao, Shun Li, Jianhua Chang
Vernier-effect self-injection locking is widely researched nowadays in frontiers of ultra-narrow linewidth lasers, owing to its simple design and independent of single frequency lasers. In this paper, for the first time we utilize this technology to realize an orthogonal-polarization-switching fiber laser, by a non-polarization-maintaining fiber laser (NPM-FL) self-injection locking to a high-Q fiber resonator (fiber-R). The NPM-FL is constructed in a mid-length linear cavity, with its longitudinal modes distributing in two orthogonal polarization and having a free spectral range (FSR) of 213 MHz. By selecting different single longitudinal mode (SLM) using the vernier-effect self-injection locking, orthogonal polarization switching of the locked NPM-FL is finally achieved. The orthogonal-polarization-switching fiber laser has a high polarization extinction ratio (PER) of ∼40 dB and an ultra-narrow spectral linewidth at ten-Hz level. This laser can be used in advanced sensing and LIDARs, where relative or differential measurements at two orthogonal polarizations are required.
{"title":"Orthogonal-polarization-switching fiber laser using vernier-effect self-injection locking","authors":"Liyun Hao, Shun Li, Jianhua Chang","doi":"10.1016/j.optlastec.2025.112541","DOIUrl":"10.1016/j.optlastec.2025.112541","url":null,"abstract":"<div><div>Vernier-effect self-injection locking is widely researched nowadays in frontiers of ultra-narrow linewidth lasers, owing to its simple design and independent of single frequency lasers. In this paper, for the first time we utilize this technology to realize an orthogonal-polarization-switching fiber laser, by a non-polarization-maintaining fiber laser (NPM-FL) self-injection locking to a high-Q fiber resonator (fiber-R). The NPM-FL is constructed in a mid-length linear cavity, with its longitudinal modes distributing in two orthogonal polarization and having a free spectral range (FSR) of 213 MHz. By selecting different single longitudinal mode (SLM) using the vernier-effect self-injection locking, orthogonal polarization switching of the locked NPM-FL is finally achieved. The orthogonal-polarization-switching fiber laser has a high polarization extinction ratio (PER) of ∼40 dB and an ultra-narrow spectral linewidth at ten-Hz level. This laser can be used in advanced sensing and LIDARs, where relative or differential measurements at two orthogonal polarizations are required.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112541"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150092","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}
Porosity is one of the most important defects in laser cladding (LC); therefore, the prediction of porosity during LC is crucial. Recently, the prediction process has been conducted on images or temperatures from only the melt pool, which hinders the prediction performance due to the incomplete characterization of defects from single-modal data. Multi-modal methods can combine images and temperature fields to provide a more complete characterization of porosity defects, but this approach is limited by data imbalance and data interaction. In this study, a novel multi-modal imbalanced data prediction network (MIDPN), which contains a data mapping module, a feature extraction module and a feature interaction module, is proposed to address these issues. For data imbalance, the data mapping module of the MIDPN uses an improved generative adversarial network that maps image data to the temperature field, with the purpose of generating missing temperature field data to resolve data imbalance. In the feature extraction module, convolutional neural networks are utilized to extract the image feature and temperature field feature of the melt pool. For data interaction, the MIDPN establishes a guided attention mechanism for image-temperature field features to facilitate the interaction of features from both modalities and utilizes the fully connected layers to obtain porosity prediction results. The experimental results show that the proposed method achieves an accuracy of 96% in predicting porosity, which is better than those of the other methods. Overall, this study significantly improved the reliability of porosity prediction, enabling more accurate quality assessment for LC monitoring, and promoting proactive defect prevention.
{"title":"A porosity prediction method for laser cladding with imbalanced multi-modal data","authors":"Zhenying Xu, Yulong Yang, Xin Liu, Pengfei Cui, Chao Chen","doi":"10.1016/j.optlastec.2025.112479","DOIUrl":"10.1016/j.optlastec.2025.112479","url":null,"abstract":"<div><div>Porosity is one of the most important defects in laser cladding (LC); therefore, the prediction of porosity during LC is crucial. Recently, the prediction process has been conducted on images or temperatures from only the melt pool, which hinders the prediction performance due to the incomplete characterization of defects from single-modal data. Multi-modal methods can combine images and temperature fields to provide a more complete characterization of porosity defects, but this approach is limited by data imbalance and data interaction. In this study, a novel multi-modal imbalanced data prediction network (MIDPN), which contains a data mapping module, a feature extraction module and a feature interaction module, is proposed to address these issues. For data imbalance, the data mapping module of the MIDPN uses an improved generative adversarial network that maps image data to the temperature field, with the purpose of generating missing temperature field data to resolve data imbalance. In the feature extraction module, convolutional neural networks are utilized to extract the image feature and temperature field feature of the melt pool. For data interaction, the MIDPN establishes a guided attention mechanism for image-temperature field features to facilitate the interaction of features from both modalities and utilizes the fully connected layers to obtain porosity prediction results. The experimental results show that the proposed method achieves an accuracy of 96% in predicting porosity, which is better than those of the other methods. Overall, this study significantly improved the reliability of porosity prediction, enabling more accurate quality assessment for LC monitoring, and promoting proactive defect prevention.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112479"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optlastec.2025.112497
Xiaobing Liu , Xingxiang Zhang , Tianjiao Fu , Kaizhi Wang , Fukun Sun , Tongzheng Bai , Duo Wang
With the increase in GPU performance, many works optimize optical systems using gradient descent (GD) based on differentiable ray tracing. However, random starting points are difficult to converge to the desired result using local optimization, due to the non-convex solution space. To overcome this problem, we selectively offer global information during optimization, provided by the best current system, to the systems that are trapped in poor local minima, namely global information selectively guided gradient descent (GISG-GD). Local optimization algorithms ensure a thorough exploration of the local solution space for each individual system. Guidance information helps poor systems escape from worthless local sub-optimal configurations and access better ones. We design two easy tasks, Cooke triple lenses, ultraviolet lenses, and one difficult task, a fairly modest aspherical lenses with FOV85°F/2.0, 4.15 mm, and distortion less than 2% with lots of constraints that should be added for practical use. All these tasks achieve imaging performances comparable to patented counterparts. Compared to benchmarks and other methods for improving GD, GISG-GD improves the valid rate by tens of times while enhancing performance, stability, and diversity. A large number of valid systems and diverse configurations are generated in a short time, taking 35, 60, and 240 min respectively. We demonstrate the use of GISG-GD to automatically generate large datasets of complex lenseses with various configurations and specifications, which will greatly facilitate deep learning-based lenses design tasks. Our work provides an effective and promising approach for designing complex optical systems and constructing lenses databases. We believe our strategy can handle more complex tasks and holds substantial potential for further enhancement.
{"title":"Global information selectively guided gradient descent for ab initio optical design","authors":"Xiaobing Liu , Xingxiang Zhang , Tianjiao Fu , Kaizhi Wang , Fukun Sun , Tongzheng Bai , Duo Wang","doi":"10.1016/j.optlastec.2025.112497","DOIUrl":"10.1016/j.optlastec.2025.112497","url":null,"abstract":"<div><div>With the increase in GPU performance, many works optimize optical systems using gradient descent (GD) based on differentiable ray tracing. However, random starting points are difficult to converge to the desired result using local optimization, due to the non-convex solution space. To overcome this problem, we selectively offer global information during optimization, provided by the best current system, to the systems that are trapped in poor local minima, namely global information selectively guided gradient descent (GISG-GD). Local optimization algorithms ensure a thorough exploration of the local solution space for each individual system. Guidance information helps poor systems escape from worthless local sub-optimal configurations and access better ones. We design two easy tasks, Cooke triple lenses, ultraviolet lenses, and one difficult task, a fairly modest aspherical lenses with FOV85°F/2.0, 4.15 mm, and distortion less than 2% with lots of constraints that should be added for practical use. All these tasks achieve imaging performances comparable to patented counterparts. Compared to benchmarks and other methods for improving GD, GISG-GD improves the valid rate by tens of times while enhancing performance, stability, and diversity. A large number of valid systems and diverse configurations are generated in a short time, taking 35, 60, and 240 min respectively. We demonstrate the use of GISG-GD to automatically generate large datasets of complex lenseses with various configurations and specifications, which will greatly facilitate deep learning-based lenses design tasks. Our work provides an effective and promising approach for designing complex optical systems and constructing lenses databases. We believe our strategy can handle more complex tasks and holds substantial potential for further enhancement.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112497"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optlastec.2025.112519
Hüseyin Üzen , Hüseyin Fırat , Salih Taha Alperen Özçelik , Elif Yusufoğlu , İpek Balıkçı Çiçek , Abdulkadir Şengür
Central Serous Chorioretinopathy (CSCR) is an ocular disease characterized by fluid accumulation under the retina, which can lead to permanent visual impairment if not diagnosed early. This study presents a deep learning-based Convolutional Neural Network (CNN) model designed to automatically diagnose acute and chronic CSCR from Optical Coherence Tomography (OCT) images through multi-level feature extraction. The proposed CNN architecture consists of consecutive layers like a traditional CNN. However, it also extracts various features by creating feature maps at four different levels (F1, F2, F3, F4) for the final feature map. The model processes information using group-wise convolution and Pointwise Convolution Block (PCB) at each level. In this way, each feature group is further processed to obtain more representative features, enabling more independent learning. After the PCB outputs, the 4 feature maps are vectorized and combined, thus creating the final feature map. Finally, classification prediction scores are obtained by applying a fully connected layer and softmax function to this feature map. The experimental study utilized two datasets obtained from Elazığ Ophthalmology Polyclinic. The dataset includes 3860 OCT images from 488 individuals, with images categorized into acute CSCR, chronic CSCR, wet AMD, dry AMD, and healthy controls. Our proposed method achieves an increase in accuracy of 0.77%, attaining 96.40% compared to the highest previous accuracy of 95.73% by ResNet101. Precision is enhanced by 0.95%, reaching 95.16% over ResNet101′s 94.21%. The sensitivity (recall) is improved by 0.90%, achieving 95.65% versus ResNet101′s 94.75%. Additionally, the F1 score is increased by 0.93%, attaining 95.38% compared to ResNet101′s 94.45%. These results illustrate the effectiveness of our method, offering more precise and reliable diagnostic capabilities in OCT image classification. In conclusion, this study demonstrates the potential of artificial intelligence-supported diagnostic tools in the analysis of OCT images and contributes significantly to the development of early diagnosis and treatment strategies.
{"title":"Central serous retinopathy classification with deep learning-based multilevel feature extraction from optical coherence tomography images","authors":"Hüseyin Üzen , Hüseyin Fırat , Salih Taha Alperen Özçelik , Elif Yusufoğlu , İpek Balıkçı Çiçek , Abdulkadir Şengür","doi":"10.1016/j.optlastec.2025.112519","DOIUrl":"10.1016/j.optlastec.2025.112519","url":null,"abstract":"<div><div>Central Serous Chorioretinopathy (CSCR) is an ocular disease characterized by fluid accumulation under the retina, which can lead to permanent visual impairment if not diagnosed early. This study presents a deep learning-based Convolutional Neural Network (CNN) model designed to automatically diagnose acute and chronic CSCR from Optical Coherence Tomography (OCT) images through multi-level feature extraction. The proposed CNN architecture consists of consecutive layers like a traditional CNN. However, it also extracts various features by creating feature maps at four different levels (F1, F2, F3, F4) for the final feature map. The model processes information using group-wise convolution and Pointwise Convolution Block (PCB) at each level. In this way, each feature group is further processed to obtain more representative features, enabling more independent learning. After the PCB outputs, the 4 feature maps are vectorized and combined, thus creating the final feature map. Finally, classification prediction scores are obtained by applying a fully connected layer and softmax function to this feature map. The experimental study utilized two datasets obtained from Elazığ Ophthalmology Polyclinic. The dataset includes 3860 OCT images from 488 individuals, with images categorized into acute CSCR, chronic CSCR, wet AMD, dry AMD, and healthy controls. Our proposed method achieves an increase in accuracy of 0.77%, attaining 96.40% compared to the highest previous accuracy of 95.73% by ResNet101. Precision is enhanced by 0.95%, reaching 95.16% over ResNet101′s 94.21%. The sensitivity (recall) is improved by 0.90%, achieving 95.65% versus ResNet101′s 94.75%. Additionally, the F1 score is increased by 0.93%, attaining 95.38% compared to ResNet101′s 94.45%. These results illustrate the effectiveness of our method, offering more precise and reliable diagnostic capabilities in OCT image classification. In conclusion, this study demonstrates the potential of artificial intelligence-supported diagnostic tools in the analysis of OCT images and contributes significantly to the development of early diagnosis and treatment strategies.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112519"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optlastec.2025.112532
Yu Sun , Chenguang Guo , Jianzhuo Zhang , Weibing Dai , Guochao Zhao , Binghao Lu , Shengli Xue , Xin Mei
Laser technology, with its concentrated energy, precise guidance, and non-contact operation, is used to thermally fracture hard rock, thereby enhancing the efficiency of rock cutting and reducing cutter wear. Clarifying the degree of strength weakening in laser-irradiated rock is crucial for improving rock-cutting efficiency. The weakening behavior of granite strength was analyzed from the perspective of phase proportion. The study examined how the composition and phase proportions differ between irradiated and non-irradiated granite under various irradiation temperatures. The effects of laser power, irradiation distance, and exposure time on thermal crack morphology, compressive strength, and thermal stress in granite were analyzed using both numerical modeling and experimental data. Specific conclusions are shown as follows: During localized laser irradiation, granite exhibits thermal phenomena such as cracking, melting, and vaporization, which intensify with increased heat absorption. Phase analysis shows a decrease in high-hardness olivine content from 47.1 % to 0.0 % and an increase in low-hardness perovskite content from 0.0 % to 31.6 %, indicating mechanical weakening in irradiated areas. From the strength perspective, a temperature gradient around the irradiation center induces thermal stress. As laser power and exposure time increase, or irradiation distance decreases, this temperature difference intensifies, further weakening granite strength. When the laser power, irradiation distance and time are 1400 W, 40 mm and 25 s, the maximum reduction values of the granite sample strength are 41.34 %, 22.18 % and 18.40 %, respectively. This study demonstrates a significant improvement in the efficiency of thermal fracturing for high-strength granite.
{"title":"Analysis of weakening degree of mechanical properties of granite irradiated by laser","authors":"Yu Sun , Chenguang Guo , Jianzhuo Zhang , Weibing Dai , Guochao Zhao , Binghao Lu , Shengli Xue , Xin Mei","doi":"10.1016/j.optlastec.2025.112532","DOIUrl":"10.1016/j.optlastec.2025.112532","url":null,"abstract":"<div><div>Laser technology, with its concentrated energy, precise guidance, and non-contact operation, is used to thermally fracture hard rock, thereby enhancing the efficiency of rock cutting and reducing cutter wear. Clarifying the degree of strength weakening in laser-irradiated rock is crucial for improving rock-cutting efficiency. The weakening behavior of granite strength was analyzed from the perspective of phase proportion. The study examined how the composition and phase proportions differ between irradiated and non-irradiated granite under various irradiation temperatures. The effects of laser power, irradiation distance, and exposure time on thermal crack morphology, compressive strength, and thermal stress in granite were analyzed using both numerical modeling and experimental data. Specific conclusions are shown as follows: During localized laser irradiation, granite exhibits thermal phenomena such as cracking, melting, and vaporization, which intensify with increased heat absorption. Phase analysis shows a decrease in high-hardness olivine content from 47.1 % to 0.0 % and an increase in low-hardness perovskite content from 0.0 % to 31.6 %, indicating mechanical weakening in irradiated areas. From the strength perspective, a temperature gradient around the irradiation center induces thermal stress. As laser power and exposure time increase, or irradiation distance decreases, this temperature difference intensifies, further weakening granite strength. When the laser power, irradiation distance and time are 1400 W, 40 mm and 25 s, the maximum reduction values of the granite sample strength are 41.34 %, 22.18 % and 18.40 %, respectively. This study demonstrates a significant improvement in the efficiency of thermal fracturing for high-strength granite.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"184 ","pages":"Article 112532"},"PeriodicalIF":4.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150679","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}
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