In this investigation, laser induced micro/nanostructures are generated on the titanium surface for improving its applicability in biomedical engineering. Emphasis is given on controlled manipulation of surface wettability which play the crucial role in several applications, including biomedical implants, tribological systems, self-cleaning surfaces, anti-corrosion coatings and etc. Three distinct scanning schemes, raster, cross-raster and shift-raster scans are applied under varying laser parameter to generate structures on the Ti surface. Surface morphology, roughness, and wettability are systematically studies using SEM, 3D profilometry and static contact angle measurements respectively. It has been observed that the laser fluence and scanning strategy significantly influence the shape, size and distributions of generated structures. Formation of ripples and microgroove structures on the surface at relatively low laser fluence exhibit the superhydrophilic behaviour whereas superhydrophobic behaviours are observed in hierarchical structuring at high laser fluence. Further, role of surface chemistry of different textures are also correlated with their hydrophilic and hydrophobic behaviour using optical emission spectroscopy. The observed correlation between laser processing parameters, surface topography and wettability establishes a versatile, single step approach for functionalizing surfaces as per desired applications.
{"title":"Laser generated micro/nanotexturing and controllable wettability of the titanium surface for its implications in different fields","authors":"P.Chandrakanta Singh, Vineet Kumar Shukla, R.K. Singh","doi":"10.1016/j.optlastec.2026.114938","DOIUrl":"10.1016/j.optlastec.2026.114938","url":null,"abstract":"<div><div>In this investigation, laser induced micro/nanostructures are generated on the titanium surface for improving its applicability in biomedical engineering. Emphasis is given on controlled manipulation of surface wettability which play the crucial role in several applications, including biomedical implants, tribological systems, self-cleaning surfaces, anti-corrosion coatings and etc. Three distinct scanning schemes, raster, cross-raster and shift-raster scans are applied under varying laser parameter to generate structures on the Ti surface. Surface morphology, roughness, and wettability are systematically studies using SEM, 3D profilometry and static contact angle measurements respectively. It has been observed that the laser fluence and scanning strategy significantly influence the shape, size and distributions of generated structures. Formation of ripples and microgroove structures on the surface at relatively low laser fluence exhibit the superhydrophilic behaviour whereas superhydrophobic behaviours are observed in hierarchical structuring at high laser fluence. Further, role of surface chemistry of different textures are also correlated with their hydrophilic and hydrophobic behaviour using optical emission spectroscopy. The observed correlation between laser processing parameters, surface topography and wettability establishes a versatile, single step approach for functionalizing surfaces as per desired applications.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"198 ","pages":"Article 114938"},"PeriodicalIF":5.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192024","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 : 2026-06-01Epub Date: 2026-02-13DOI: 10.1016/j.optlastec.2026.114871
Zhensheng Sun , Peilei Zhang , Shijie Song , Kefan Chen , Keran Jiang , Guanglong Chen , Qinghua Lu , Chao Fang
Short Pulse Laser (SPL) and Ultrashort Pulse Laser (USPL) etching are pivotal for fabricating high-precision components in extreme manufacturing. However, their industrial deployment faces significant challenges. The highly non-linear nature of laser-material interactions necessitates expensive trial-and-error, while pure data-driven models suffer from “black-box” interpretability issues and data scarcity, and traditional static optimization fails to adapt to dynamic disturbances during real-time processing. To address these issues, machine learning (ML) and metaheuristic algorithms (MA) have been widely used in SPL and USPL processing. The primary objective of this review is to systematically synthesize and critically evaluate the applications of Machine Learning (ML) and MA in SPL/USPL etching, specifically focusing on drilling, microchannel fabrication, and Laser-Induced Periodic Surface Structures (LIPSS) . We categorize core strategies into “Forward Modeling” (quality prediction) and “Reverse Design” (parameter optimization) to elucidate how these algorithms mitigate the aforementioned challenges, and providing a forward-looking perspective, highlighting Physics-Informed Machine Learning (PINNs) for enhancing interpretability with sparse data. This review expands on the little-covered part of the existing review literature on the application of ML and MA in the field of laser processing and summarises the effectiveness of different ML models and MA for SPL and USPL in terms of etching. It further explores the potential of emerging, multiple ML converged processing and provides an outlook on novel trends and challenges at the intersection of laser etching and ML.
{"title":"A review of the application of machine learning in short-pulse and ultrashort-pulse laser etching","authors":"Zhensheng Sun , Peilei Zhang , Shijie Song , Kefan Chen , Keran Jiang , Guanglong Chen , Qinghua Lu , Chao Fang","doi":"10.1016/j.optlastec.2026.114871","DOIUrl":"10.1016/j.optlastec.2026.114871","url":null,"abstract":"<div><div>Short Pulse Laser (SPL) and Ultrashort Pulse Laser (USPL) etching are pivotal for fabricating high-precision components in extreme manufacturing. However, their industrial deployment faces significant challenges. The highly non-linear nature of laser-material interactions necessitates expensive trial-and-error, while pure data-driven models suffer from “black-box” interpretability issues and data scarcity, and traditional static optimization fails to adapt to dynamic disturbances during real-time processing. To address these issues, machine learning (ML) and metaheuristic algorithms (MA) have been widely used in SPL and USPL processing. The primary objective of this review is to systematically synthesize and critically evaluate the applications of Machine Learning (ML) and MA in SPL/USPL etching, specifically focusing on drilling, microchannel fabrication, and Laser-Induced Periodic Surface Structures (LIPSS) . We categorize core strategies into “Forward Modeling” (quality prediction) and “Reverse Design” (parameter optimization) to elucidate how these algorithms mitigate the aforementioned challenges, and providing a forward-looking perspective, highlighting Physics-Informed Machine Learning (PINNs) for enhancing interpretability with sparse data. This review expands on the little-covered part of the existing review literature on the application of ML and MA in the field of laser processing and summarises the effectiveness of different ML models and MA for SPL and USPL in terms of etching. It further explores the potential of emerging, multiple ML converged processing and provides an outlook on novel trends and challenges at the intersection of laser etching and ML.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"198 ","pages":"Article 114871"},"PeriodicalIF":5.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192015","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 : 2026-06-01Epub Date: 2026-02-06DOI: 10.1016/j.optlastec.2026.114787
Tanzeel Ur Rahman , Guijun Li , Farman Ali , Adnan Daud Khan , Akhtar Rehman , Zhengbiao Ouyang , Haleem Afsar , Ali Alshamrani , Mardeni Roslee
Free-space optical (FSO) communication is essential for high-speed, long-range data transmission, particularly in UAV-to-ground (U2G) communication systems. However, existing FSO systems face critical challenges, including beam misalignment due to UAV movement, turbulence-induced signal degradation, and inefficient modulation schemes that fail to adapt dynamically to changing atmospheric conditions. Current solutions, such as mechanical beam tracking systems and conventional phased arrays, suffer from high complexity, limited scalability, and suboptimal energy efficiency, making them less suitable for U2G operations. Additionally, existing adaptive modulation schemes lack robustness in severe turbulence, leading to increased bit error rates and reduced system performance. This study proposes a Fiber-Array Beamforming and Modulation Scheme with Hybrid Switching Standards for enhanced U2G-FSO communication to address these challenges. The proposed system integrates a photodiode-based fiber-array antenna with a polymer-based nanophotonic optical phased array (OPA) to achieve precise beamforming and automatic misalignment correction. A hybrid switching standard is implemented to adjust the modulation format dynamically based on real-time turbulence variations, optimizing signal integrity and spectral efficiency. The research methodology includes mathematical modeling for phase optimization, experimental validation of beam steering performance, and turbulence-aware simulations to assess system adaptability. Experimental results demonstrate that the proposed system achieves a 3-dB beamwidth reduction of 8.5, a beam steering range of 20, and a 10 dB increase in power output, significantly improving signal robustness in turbulent atmospheric conditions. The hybrid switching mechanism effectively reduces SNR switching threshold deviation from conventional values, allowing for seamless modulation transitions and improved link stability.
{"title":"Fiber-array beamforming and modulation scheme with hybrid switching techniques for U2G-free space optical communication","authors":"Tanzeel Ur Rahman , Guijun Li , Farman Ali , Adnan Daud Khan , Akhtar Rehman , Zhengbiao Ouyang , Haleem Afsar , Ali Alshamrani , Mardeni Roslee","doi":"10.1016/j.optlastec.2026.114787","DOIUrl":"10.1016/j.optlastec.2026.114787","url":null,"abstract":"<div><div>Free-space optical (FSO) communication is essential for high-speed, long-range data transmission, particularly in UAV-to-ground (U2G) communication systems. However, existing FSO systems face critical challenges, including beam misalignment due to UAV movement, turbulence-induced signal degradation, and inefficient modulation schemes that fail to adapt dynamically to changing atmospheric conditions. Current solutions, such as mechanical beam tracking systems and conventional phased arrays, suffer from high complexity, limited scalability, and suboptimal energy efficiency, making them less suitable for U2G operations. Additionally, existing adaptive modulation schemes lack robustness in severe turbulence, leading to increased bit error rates and reduced system performance. This study proposes a Fiber-Array Beamforming and Modulation Scheme with Hybrid Switching Standards for enhanced U2G-FSO communication to address these challenges. The proposed system integrates a photodiode-based fiber-array antenna with a polymer-based nanophotonic optical phased array (OPA) to achieve precise beamforming and automatic misalignment correction. A hybrid switching standard is implemented to adjust the modulation format dynamically based on real-time turbulence variations, optimizing signal integrity and spectral efficiency. The research methodology includes mathematical modeling for phase optimization, experimental validation of beam steering performance, and turbulence-aware simulations to assess system adaptability. Experimental results demonstrate that the proposed system achieves a 3-dB beamwidth reduction of 8.5<span><math><msup><mspace></mspace><mrow><mo>∘</mo></mrow></msup></math></span>, a beam steering range of 20<span><math><msup><mspace></mspace><mrow><mo>∘</mo></mrow></msup></math></span>, and a 10 dB increase in power output, significantly improving signal robustness in turbulent atmospheric conditions. The hybrid switching mechanism effectively reduces SNR switching threshold deviation from conventional values, allowing for seamless modulation transitions and improved link stability.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"198 ","pages":"Article 114787"},"PeriodicalIF":5.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192323","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 : 2026-06-01Epub Date: 2026-02-11DOI: 10.1016/j.optlastec.2026.114921
Yujing Shen , Yan Xuan , Shuo Sun , Pengcheng Du , Jin Li
Driven by increasing demand for portable magnetic field detection in multiple application scenarios, optically pumped atomic magnetometers (OPAMs) are rapidly advancing toward smaller, portable designs, with the single-beam elliptically polarized architecture offering inherent compactness due to its simplified optical path. However, traditional implementations that use bulky multiple waveplates for polarization conversion fundamentally hinder system miniaturization. This study proposes and experimentally validates a new scheme for a chip-scale integrated OPAM. The scheme is based on a 39K atom system with an Mx-mode, single-beam configuration. Its core innovation lies in employing a polarization-independent cascaded metasurface to replace the traditional multi-component polarization optics system with a monolithic device. Experiments demonstrate that this scheme, under a 10,000 nT magnetic field, maintains a sensitivity comparable to that of a commercial waveplate-based system (approximately 8.36pT/Hz1/2 in the 70–90 Hz band) while achieving a reduction in the core optical module volume of over 60% and keeping polarization control accuracy within 3%. This work successfully verifies the feasibility of the metasurface-based approach for realizing miniaturized, manual-alignment-free optical pumping, thereby paving the way for and laying a key technical foundation for the eventual realization of fully chip-integrated, field-deployable quantum magnetometers.
{"title":"A miniaturized atomic magnetometer enabled by cascaded metasurfaces","authors":"Yujing Shen , Yan Xuan , Shuo Sun , Pengcheng Du , Jin Li","doi":"10.1016/j.optlastec.2026.114921","DOIUrl":"10.1016/j.optlastec.2026.114921","url":null,"abstract":"<div><div>Driven by increasing demand for portable magnetic field detection in multiple application scenarios, optically pumped atomic magnetometers (OPAMs) are rapidly advancing toward smaller, portable designs, with the single-beam elliptically polarized architecture offering inherent compactness due to its simplified optical path. However, traditional implementations that use bulky multiple waveplates for polarization conversion fundamentally hinder system miniaturization. This study proposes and experimentally validates a new scheme for a chip-scale integrated OPAM. The scheme is based on a <sup>39</sup>K atom system with an Mx-mode, single-beam configuration. Its core innovation lies in employing a polarization-independent cascaded metasurface to replace the traditional multi-component polarization optics system with a monolithic device. Experiments demonstrate that this scheme, under a 10,000 nT magnetic field, maintains a sensitivity comparable to that of a commercial waveplate-based system (approximately 8.36pT/Hz<sup>1/2</sup> in the 70–90 Hz band) while achieving a reduction in the core optical module volume of over 60% and keeping polarization control accuracy within 3%. This work successfully verifies the feasibility of the metasurface-based approach for realizing miniaturized, manual-alignment-free optical pumping, thereby paving the way for and laying a key technical foundation for the eventual realization of fully chip-integrated, field-deployable quantum magnetometers.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"198 ","pages":"Article 114921"},"PeriodicalIF":5.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192654","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 : 2026-06-01Epub Date: 2026-02-04DOI: 10.1016/j.optlastec.2026.114855
Hongzu Zhang , Li Wang , Bo Li , Hanshuang Li , Guochao Gu , Xu Zhang
This study addresses faint target detection under intense backgrounds by proposing a novel hollow truncated conical external occulter for stray light suppression in imaging systems. Unlike material-dependent transmittance control methods, the design innovatively optimizes transmittance distribution via geometric parameter tuning, significantly reducing edge diffraction and attenuating image-plane stray light. Leveraging TRACEPRO’s optimization capabilities and gradient transmittance diffraction theory, a precise optical model is established, with the occulter’s diffraction and stray light characteristics quantitatively analyzed through numerical optimization workflows. During optimization, the occulter structure and lens configuration are co-optimized to enhance imaging quality while boosting weak-signal detection capability. Combined with an internal occulter and Lyot stop in a multi-stage suppression scheme, the design reduces image-plane background irradiance to the 10−8 order, maintaining effective imaging at a minimum angular separation of 0.5°. This approach discards the traditional method of achieving transmittance variation through multiple materials, but rather leverages flexible geometric structures to control a single material, enabling precise optimization of graded transmittance. It not only exhibits excellent diffraction light suppression performance but also opens up a novel technical pathway for the manufacturing of external occulters. Additionally, it effectively mitigates strong background interference such as solar radiation, significantly enhancing space target detection accuracy and providing reliable support for weak signal acquisition in space target monitoring and exploration missions.
{"title":"Apodized hollow conical occulter with gradient transmittance for stray-light suppression","authors":"Hongzu Zhang , Li Wang , Bo Li , Hanshuang Li , Guochao Gu , Xu Zhang","doi":"10.1016/j.optlastec.2026.114855","DOIUrl":"10.1016/j.optlastec.2026.114855","url":null,"abstract":"<div><div>This study addresses faint target detection under intense backgrounds by proposing a novel hollow truncated conical external occulter for stray light suppression in imaging systems. Unlike material-dependent transmittance control methods, the design innovatively optimizes transmittance distribution via geometric parameter tuning, significantly reducing edge diffraction and attenuating image-plane stray light. Leveraging TRACEPRO’s optimization capabilities and gradient transmittance diffraction theory, a precise optical model is established, with the occulter’s diffraction and stray light characteristics quantitatively analyzed through numerical optimization workflows. During optimization, the occulter structure and lens configuration are co-optimized to enhance imaging quality while boosting weak-signal detection capability. Combined with an internal occulter and Lyot stop in a multi-stage suppression scheme, the design reduces image-plane background irradiance to the 10<sup>−8</sup> order, maintaining effective imaging at a minimum angular separation of 0.5°. This approach discards the traditional method of achieving transmittance variation through multiple materials, but rather leverages flexible geometric structures to control a single material, enabling precise optimization of graded transmittance. It not only exhibits excellent diffraction light suppression performance but also opens up a novel technical pathway for the manufacturing of external occulters. Additionally, it effectively mitigates strong background interference such as solar radiation, significantly enhancing space target detection accuracy and providing reliable support for weak signal acquisition in space target monitoring and exploration missions.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"198 ","pages":"Article 114855"},"PeriodicalIF":5.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116763","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}
Optical limiting materials are essential for the innovation of optoelectronic devices and human eyes in defense industry. The two most important parameters for an ideal optical limiter are the optical limiting spectral range and a low optical limiting threshold value. Herein, silver nanowires (Ag NWs) were examined in both colloidal dispersion and as thin films embedded within a polymethyl methacrylate (PMMA) matrix to evaluate their optical limiting performance across an ultrabroad wavelength range. PMMA polymer, which does not exhibit nonlinear absorption, was used to reveal the nonlinear optical property of Ag NWs. For this purpose, the nonlinear optical response of colloidal and thin film Ag NWs was investigated using the open aperture Z-scan technique, under varying excitation wavelengths and input intensities using a femtosecond pulsed laser system. To gain deeper insight into the underlying mechanism of nonlinear optical behavior, ultrafast pump–probe spectroscopy measurements were conducted. Open aperture Z-scan experiments revealed that both colloidal and thin-film AgNWs exhibit similar nonlinear optical behavior under excitation wavelengths ranging from 400 to 800 nm with increments of 100 nm. Moreover, to analyze nonlinear absorption properties in near infrared region, experiments were also carried out using pulsed laser excitation at 1200 and 1600 nm. Among the excitation wavelengths studied, 1600 nm located in the longitudinal mode of surface plasmon resonance of Ag NWs produced the highest βeff value. This enhancement was attributed to multiphoton absorption and plasmon-enhanced excited-state absorption (ESA) processes. Under 1200 and 1600 nm excitation, the colloidal Ag NW dispersion exhibited reverse saturable absorption (RSA) signals superimposed on saturable absorption (SA) behavior, in contrast to the thin-film form, where only RSA was observed. Across the ultrabroadband excitation range of 400-1600 nm, the optical limiting performance exhibited threshold values ranging from 0.02 to 0.33 J/cm2, indicating wavelength-dependent nonlinear absorption behavior. This work is among the first to systematically investigate Ag NW based optical limiters over an ultrabroad excitation range extending from the visible to the near-infrared (400–1600 nm). Overall, Ag NWs in both colloidal and thin-film forms exhibited ultrabroadband optical limiting responses, highlighting their potential for photonic and optoelectronic applications.
{"title":"Plasmon-enhanced ultrabroadband optical limiting performance of colloidal and thin film silver nanowires","authors":"Elif Yildiz , Nur Unal , Onuralp Cakir , Yasemin Pepe , Sahin Coskun , Ahmet Karatay , Husnu Emrah Unalan , Ayhan Elmali","doi":"10.1016/j.optlastec.2026.114741","DOIUrl":"10.1016/j.optlastec.2026.114741","url":null,"abstract":"<div><div>Optical limiting materials are essential for the innovation of optoelectronic devices and human eyes in defense industry. The two most important parameters for an ideal optical limiter are the optical limiting spectral range and a low optical limiting threshold value. Herein, silver nanowires (Ag NWs) were examined in both colloidal dispersion and as thin films embedded within a polymethyl methacrylate (PMMA) matrix to evaluate their optical limiting performance across an ultrabroad wavelength range. PMMA polymer, which does not exhibit nonlinear absorption, was used to reveal the nonlinear optical property of Ag NWs. For this purpose, the nonlinear optical response of colloidal and thin film Ag NWs was investigated using the open aperture Z-scan technique, under varying excitation wavelengths and input intensities using a femtosecond pulsed laser system. To gain deeper insight into the underlying mechanism of nonlinear optical behavior, ultrafast pump–probe spectroscopy measurements were conducted. Open aperture Z-scan experiments revealed that both colloidal and thin-film AgNWs exhibit similar nonlinear optical behavior under excitation wavelengths ranging from 400 to 800 nm with increments of 100 nm. Moreover, to analyze nonlinear absorption properties in near infrared region, experiments were also carried out using pulsed laser excitation at 1200 and 1600 nm. Among the excitation wavelengths studied, 1600 nm located in the longitudinal mode of surface plasmon resonance of Ag NWs produced the highest <em>β<sub>eff</sub></em> value. This enhancement was attributed to multiphoton absorption and plasmon-enhanced excited-state absorption (ESA) processes. Under 1200 and 1600 nm excitation, the colloidal Ag NW dispersion exhibited reverse saturable absorption (RSA) signals superimposed on saturable absorption (SA) behavior, in contrast to the thin-film form, where only RSA was observed. Across the ultrabroadband excitation range of 400-1600 nm, the optical limiting performance exhibited threshold values ranging from 0.02 to 0.33 J/cm<sup>2</sup>, indicating wavelength-dependent nonlinear absorption behavior. This work is among the first to systematically investigate Ag NW based optical limiters over an ultrabroad excitation range extending from the visible to the near-infrared (400–1600 nm). Overall, Ag NWs in both colloidal and thin-film forms exhibited ultrabroadband optical limiting responses, highlighting their potential for photonic and optoelectronic applications.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"197 ","pages":"Article 114741"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036381","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 : 2026-05-01Epub Date: 2026-01-31DOI: 10.1016/j.optlastec.2026.114847
Luigi Melchiorre , Giansergio Menduni , Giovanni Magno , Liam O’Faolain , Pietro Patimisco , Vincenzo Spagnolo , Angelo Sampaolo
This paper presents a comparison between quartz-enhanced photoacoustic spectroscopy (QEPAS) and beat-frequency QEPAS (BF-QEPAS) techniques for the sequential detection of methane (C1) and ethane (C2) in the near-infrared spectral range. Both approaches exploit a T-shaped quartz tuning fork (QTF)—coupled with acoustic resonator tubes—as sensitive element but differ fundamentally in the signal generation and acquisition methods. While conventional QEPAS-based approach requires periodic QTF characterization and longer acquisition time, BF-QEPAS enables simultaneous measurement of target gas concentration, QTF resonance frequency and quality factor through analysis of transient response signals. Experiments were performed using a laser diode emitting at a central wavelength of 1683.53 nm, targeting C1 and C2 absorption features. Our results demonstrate that the BF-QEPAS approach significantly reduces measurement time from minutes to few seconds and maintains comparable detection sensitivity, also for broadband absorbers such as ethane. For methane, minimum detection limits (MDLs) of 1.7 parts-per-million (ppm) and 5 ppm were achieved with QEPAS and BF-QEPAS techniques, respectively, while for ethane MDLs of 20 ppm and 62 ppm were obtained, respectively. The BF-QEPAS technique enables continuous, uninterrupted monitoring of both target gases in sequential detection mode, with the simultaneous validation of the measurement through the evaluation of the QTF resonance parameters.
{"title":"Comparison of QEPAS and BF-QEPAS approaches for methane and ethane sequential detection in the near-IR spectral range","authors":"Luigi Melchiorre , Giansergio Menduni , Giovanni Magno , Liam O’Faolain , Pietro Patimisco , Vincenzo Spagnolo , Angelo Sampaolo","doi":"10.1016/j.optlastec.2026.114847","DOIUrl":"10.1016/j.optlastec.2026.114847","url":null,"abstract":"<div><div>This paper presents a comparison between quartz-enhanced photoacoustic spectroscopy (QEPAS) and beat-frequency QEPAS (BF-QEPAS) techniques for the sequential detection of methane (C1) and ethane (C2) in the near-infrared spectral range. Both approaches exploit a T-shaped quartz tuning fork (QTF)—coupled with acoustic resonator tubes—as sensitive element but differ fundamentally in the signal generation and acquisition methods. While conventional QEPAS-based approach requires periodic QTF characterization and longer acquisition time, BF-QEPAS enables simultaneous measurement of target gas concentration, QTF resonance frequency and quality factor through analysis of transient response signals. Experiments were performed using a laser diode emitting at a central wavelength of 1683.53 nm, targeting C1 and C2 absorption features. Our results demonstrate that the BF-QEPAS approach significantly reduces measurement time from minutes to few seconds and maintains comparable detection sensitivity, also for broadband absorbers such as ethane. For methane, minimum detection limits (MDLs) of 1.7 parts-per-million (ppm) and 5 ppm were achieved with QEPAS and BF-QEPAS techniques, respectively, while for ethane MDLs of 20 ppm and 62 ppm were obtained, respectively. The BF-QEPAS technique enables continuous, uninterrupted monitoring of both target gases in sequential detection mode, with the simultaneous validation of the measurement through the evaluation of the QTF resonance parameters.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"197 ","pages":"Article 114847"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079664","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 : 2026-05-01Epub Date: 2026-01-16DOI: 10.1016/j.optlastec.2026.114707
Liang Mei , Hangyi Liu , Xuekai Hong , Xinhong Wang , Yuan Cheng , Xinglong Yang , Zheng Wang , Wei Peng , Zheng Kong
Scheimpflug lidar (SLidar) has emerged as a pivotal tool in atmospheric remote sensing, providing high-resolution detection of aerosol spatiotemporal distributions and their optical-microphysical properties. By exploiting geometrical optics principles, range-resolved atmospheric lidar signals can be obtained from pixel intensities. However, the incident angles of scattered light, varying with the detection distance, could introduce quantum efficiency (QE) variations in tilted image sensors that distort lidar signals, particularly in near-field regimes. In this work, we propose a universal, physics-based angular response correction model (ARCM) that unifies laser scattering angle, image sensor tilt, and receiver off-axis light effects into a pixel-level correction framework. The ARCM introduces a pixelwise correction factor to compensate for QE-induced signal distortions. The performance of the ARCM was systematically validated through theoretical simulations and atmospheric experiments using three SLidar systems with distinct optical configurations, covering both near-horizontal and vertical detection scenarios. Our results reveal discrepancies in the QE angular response among the three SLidar configurations, with extinction coefficient retrieval errors between uncorrected and corrected signals ranging from 3% to 10% at the minimum detection range. Besides, six-day horizontal scanning experiments were also conducted, and the ARCM-corrected extinction coefficients showed strong agreement with in-situ PM2.5 measurements, with a correlation coefficient of 0.904. Furthermore, quantitative analysis shows that focal length serves as the dominant factor suppressing QE fluctuations, while sensor tilt determines the operational region on the QE curve, resulting in a non-monotonic coupling between SLidar configurations and relative QEs. This work significantly advances the measurement accuracy of the SLidar signal particularly in close range, thereby enhancing its reliability for critical applications in aerosol sensing.
{"title":"Influence and calibration of the angular response of the image sensor on lidar profiles in Scheimpflug lidar techniques","authors":"Liang Mei , Hangyi Liu , Xuekai Hong , Xinhong Wang , Yuan Cheng , Xinglong Yang , Zheng Wang , Wei Peng , Zheng Kong","doi":"10.1016/j.optlastec.2026.114707","DOIUrl":"10.1016/j.optlastec.2026.114707","url":null,"abstract":"<div><div>Scheimpflug lidar (SLidar) has emerged as a pivotal tool in atmospheric remote sensing, providing high-resolution detection of aerosol spatiotemporal distributions and their optical-microphysical properties. By exploiting geometrical optics principles, range-resolved atmospheric lidar signals can be obtained from pixel intensities. However, the incident angles of scattered light, varying with the detection distance, could introduce quantum efficiency (QE) variations in tilted image sensors that distort lidar signals, particularly in near-field regimes. In this work, we propose a universal, physics-based angular response correction model (ARCM) that unifies laser scattering angle, image sensor tilt, and receiver off-axis light effects into a pixel-level correction framework. The ARCM introduces a pixelwise correction factor to compensate for QE-induced signal distortions. The performance of the ARCM was systematically validated through theoretical simulations and atmospheric experiments using three SLidar systems with distinct optical configurations, covering both near-horizontal and vertical detection scenarios. Our results reveal discrepancies in the QE angular response among the three SLidar configurations, with extinction coefficient retrieval errors between uncorrected and corrected signals ranging from 3% to 10% at the minimum detection range. Besides, six-day horizontal scanning experiments were also conducted, and the ARCM-corrected extinction coefficients showed strong agreement with in-situ PM<sub>2.5</sub> measurements, with a correlation coefficient of 0.904. Furthermore, quantitative analysis shows that focal length serves as the dominant factor suppressing QE fluctuations, while sensor tilt determines the operational region on the QE curve, resulting in a non-monotonic coupling between SLidar configurations and relative QEs. This work significantly advances the measurement accuracy of the SLidar signal particularly in close range, thereby enhancing its reliability for critical applications in aerosol sensing.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"197 ","pages":"Article 114707"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981986","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 : 2026-05-01Epub Date: 2026-01-31DOI: 10.1016/j.optlastec.2026.114857
Jinyang Li , Dengji Guo , Ta-Cheng Mo , Yu-Hsiang Hsu , Changliang Zhu , Shien-Ping Feng , Hung-Fei Kuo
As semiconductor devices continue to scale down, manufacturing processes face increasing challenges. This necessitates more efficient metrology techniques to ensure process quality. Critical dimension (CD) measurement is a crucial step in process verification, as deviations in CD directly impact device performance. Optical critical dimension (OCD) method, based on scatterometry, offers a rapid and non-invasive solution in precise measurement. It can analyze diffraction images generated from periodic measurement marks and compare them with references to achieve linewidth measurements. In this work, an OCD measurement framework enhanced with data augmentation via a transformer-based conditional generative adversarial network (TCGAN) is proposed. Grating measurement marks with designed CDs ranging from 400 nm to 600 nm were simulated to generate diffraction images. The two-directional two-dimensional principal components analysis ((2D)2PCA) was applied to extract features and convert these images into sequential data. A TCGAN model was then trained to expand the diffraction dataset, increasing it to 21,000 samples. The augmented dataset was used to train a regression model capable of accurately predicting the linewidth of the grating measurement marks. The proposed model achieved a root mean squared error (RMSE) of 0.70 nm and a coefficient of determination (R2) of 0.99 in simulation test, indicating high linear correlation between predictions and ground truth. Experimental validation was conducted using fabricated measurement marks and the designed optics, achieving an RMSE of 1.14 nm, further confirming the effectiveness of TCGAN-assisted OCD measurement method.
随着半导体器件的不断缩小，制造工艺面临越来越多的挑战。这就需要更有效的计量技术来确保过程质量。关键尺寸（CD）测量是工艺验证的关键步骤，因为CD的偏差直接影响器件的性能。光学临界尺寸法（OCD）是一种基于散射法的快速、无创的精确测量方法。它可以分析由周期性测量标记产生的衍射图像，并将其与参考文献进行比较，从而实现线宽测量。在这项工作中，提出了一个通过基于变压器的条件生成对抗网络（TCGAN）增强数据增强的强迫症测量框架。对设计的CDs范围为400 ~ 600 nm的光栅测量标记进行了模拟，生成了衍射图像。利用双向二维主成分分析（two-directional two principal components analysis, 2D）2PCA提取特征，并将这些图像转换为序列数据。然后训练TCGAN模型来扩展衍射数据集，将其增加到21,000个样本。利用增强的数据集训练能够准确预测光栅测量标记线宽的回归模型。在模拟测试中，该模型的均方根误差（RMSE）为0.70 nm，决定系数（R2）为0.99，表明预测结果与实际情况具有较高的线性相关性。利用自制的测量标记和设计的光学器件进行实验验证，RMSE为1.14 nm，进一步证实了tcgan辅助OCD测量方法的有效性。
{"title":"Development of an optical critical dimension (OCD) measurement model enhanced by transformer-based data augmentation","authors":"Jinyang Li , Dengji Guo , Ta-Cheng Mo , Yu-Hsiang Hsu , Changliang Zhu , Shien-Ping Feng , Hung-Fei Kuo","doi":"10.1016/j.optlastec.2026.114857","DOIUrl":"10.1016/j.optlastec.2026.114857","url":null,"abstract":"<div><div>As semiconductor devices continue to scale down, manufacturing processes face increasing challenges. This necessitates more efficient metrology techniques to ensure process quality. Critical dimension (CD) measurement is a crucial step in process verification, as deviations in CD directly impact device performance. Optical critical dimension (OCD) method, based on scatterometry, offers a rapid and non-invasive solution in precise measurement. It can analyze diffraction images generated from periodic measurement marks and compare them with references to achieve linewidth measurements. In this work, an OCD measurement framework enhanced with data augmentation via a transformer-based conditional generative adversarial network (TCGAN) is proposed. Grating measurement marks with designed CDs ranging from 400 nm to 600 nm were simulated to generate diffraction images. The two-directional two-dimensional principal components analysis ((2D)<sup>2</sup>PCA) was applied to extract features and convert these images into sequential data. A TCGAN model was then trained to expand the diffraction dataset, increasing it to 21,000 samples. The augmented dataset was used to train a regression model capable of accurately predicting the linewidth of the grating measurement marks. The proposed model achieved a root mean squared error (RMSE) of 0.70 nm and a coefficient of determination (R<sup>2</sup>) of 0.99 in simulation test, indicating high linear correlation between predictions and ground truth. Experimental validation was conducted using fabricated measurement marks and the designed optics, achieving an RMSE of 1.14 nm, further confirming the effectiveness of TCGAN-assisted OCD measurement method.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"197 ","pages":"Article 114857"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189904","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 : 2026-05-01Epub Date: 2026-02-01DOI: 10.1016/j.optlastec.2026.114829
Shuru Chen , Zhijian Wei , Jin Li , Biqing Wang , Yuze Wang , Kai Jiao , Shengchuang Bai , Pingxue Li , Vladimir Shiryaev , Xunsi Wang
Due to pronounced hydroxyl (–OH) absorption bands around 2.7 μm in the mid-infrared region, tellurite glasses typically exhibit limited performance for mid-infrared laser transmission, which in turn constrains their suitability for Er:YAG laser delivery. This limitation arises primarily from –OH impurities, which introduce strong absorption in the mid-infrared band and significantly degrade transmission efficiency. To enhance the mid-infrared transmission performance and laser-induced damage threshold of TeO2–ZnO–La2O3 (TZL) glass, high-temperature vacuum melting was employed as a physical purification method to effectively remove –OH impurities from the glass matrix. The effects of melting temperature and vacuum level on purification efficiency were systematically investigated. Through optimization of raw-material refining and melting parameters, low-hydroxyl tellurite glass was successfully obtained, exhibiting an –OH absorption coefficient as low as 0.004 cm–1—representing a 99.8% reduction compared with conventional unpurified samples. The purified glass was subsequently extruded into core–cladding preforms and drawn into flexible fibers with a core diameter of 300 μm and a cladding diameter of 600 μm. The fabricated TZL fiber achieved a maximum stable output power of 8.3 W at 2.94 μm, corresponding to an energy density of 1061 J cm–2. To the best of our knowledge, this is the first demonstration of a tellurite fiber capable of stably delivering more than 8 W of Er:YAG laser power at 2.94 μm, highlighting its strong potential for high-power mid-infrared laser applications in surgical medicine and industrial processing.
{"title":"Low-Hydroxyl tellurite fiber for Mid-Infrared Er:YAG laser transmission","authors":"Shuru Chen , Zhijian Wei , Jin Li , Biqing Wang , Yuze Wang , Kai Jiao , Shengchuang Bai , Pingxue Li , Vladimir Shiryaev , Xunsi Wang","doi":"10.1016/j.optlastec.2026.114829","DOIUrl":"10.1016/j.optlastec.2026.114829","url":null,"abstract":"<div><div>Due to pronounced hydroxyl (–OH) absorption bands around 2.7 μm in the mid-infrared region, tellurite glasses typically exhibit limited performance for mid-infrared laser transmission, which in turn constrains their suitability for Er:YAG laser delivery. This limitation arises primarily from –OH impurities, which introduce strong absorption in the mid-infrared band and significantly degrade transmission efficiency. To enhance the mid-infrared transmission performance and laser-induced damage threshold of TeO<sub>2</sub>–ZnO–La<sub>2</sub>O<sub>3</sub> (TZL) glass, high-temperature vacuum melting was employed as a physical purification method to effectively remove –OH impurities from the glass matrix. The effects of melting temperature and vacuum level on purification efficiency were systematically investigated. Through optimization of raw-material refining and melting parameters, low-hydroxyl tellurite glass was successfully obtained, exhibiting an –OH absorption coefficient as low as 0.004 cm<sup>–1</sup>—representing a 99.8% reduction compared with conventional unpurified samples. The purified glass was subsequently extruded into core–cladding preforms and drawn into flexible fibers with a core diameter of 300 μm and a cladding diameter of 600 μm. The fabricated TZL fiber achieved a maximum stable output power of 8.3 W at 2.94 μm, corresponding to an energy density of 1061 J cm<sup>–2</sup>. To the best of our knowledge, this is the first demonstration of a tellurite fiber capable of stably delivering more than 8 W of Er:YAG laser power at 2.94 μm, highlighting its strong potential for high-power mid-infrared laser applications in surgical medicine and industrial processing.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"197 ","pages":"Article 114829"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189891","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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