Pub Date : 2022-01-01DOI: 10.29026/oea.2023.210149
Laiyang Dang, Ligang Huang, Lei-lei Shi, Fuhui Li, Guolu Yin, L. Gao, Tianyi Lan, Yujia Li, Lidan Jiang, T. Zhu
Ultra-high spectral purity lasers are of considerable research interests in numerous fields such as coherent optical communication, microwave photonics, distributed optical fiber sensing, gravitational wave detection, optical clock, and so on. Herein, to deeply purify laser spectrum with compact size under normal condition, we propose a novel and practical idea to effectively suppress the spontaneous radiation of the laser cavity through weak external distributed perturbation. Sub-sequently, a laser configuration consisting of a main lasing cavity and an external distributed feedback cavity is proposed. The feedback signal with continuous spatio-temporal phase transition controlled by a distributed feedback structure is injected into the main cavity, which can deeply suppress the coupling rate from the spontaneous radiation to the stimulated emission and extremely purify the laser spectrum. Eventually, an ultra-narrow linewidth on-chip laser system with a side mode suppression ratio greater than 80 dB, an output linewidth of 10 Hz, and a relative intensity noise less than -150 dB/Hz is successfully obtained under normal conditions. The proposed concept in this work provides a new perspective for extreme regulation of laser parameters by using weak external distributed perturbation, which can be val-id for various gain-type lasers with wide wavelength bands. Ultra-high from weak external distributed perturbation.
{"title":"Ultra-high spectral purity laser derived from weak external distributed perturbation","authors":"Laiyang Dang, Ligang Huang, Lei-lei Shi, Fuhui Li, Guolu Yin, L. Gao, Tianyi Lan, Yujia Li, Lidan Jiang, T. Zhu","doi":"10.29026/oea.2023.210149","DOIUrl":"https://doi.org/10.29026/oea.2023.210149","url":null,"abstract":"Ultra-high spectral purity lasers are of considerable research interests in numerous fields such as coherent optical communication, microwave photonics, distributed optical fiber sensing, gravitational wave detection, optical clock, and so on. Herein, to deeply purify laser spectrum with compact size under normal condition, we propose a novel and practical idea to effectively suppress the spontaneous radiation of the laser cavity through weak external distributed perturbation. Sub-sequently, a laser configuration consisting of a main lasing cavity and an external distributed feedback cavity is proposed. The feedback signal with continuous spatio-temporal phase transition controlled by a distributed feedback structure is injected into the main cavity, which can deeply suppress the coupling rate from the spontaneous radiation to the stimulated emission and extremely purify the laser spectrum. Eventually, an ultra-narrow linewidth on-chip laser system with a side mode suppression ratio greater than 80 dB, an output linewidth of 10 Hz, and a relative intensity noise less than -150 dB/Hz is successfully obtained under normal conditions. The proposed concept in this work provides a new perspective for extreme regulation of laser parameters by using weak external distributed perturbation, which can be val-id for various gain-type lasers with wide wavelength bands. Ultra-high from weak external distributed perturbation.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69520140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2022-01-01DOI: 10.29026/oea.2023.220048
D. Pirone, Daniele G Sirico, L. Miccio, V. Bianco, M. Mugnano, D. D. Giudice, G. Pasquinelli, S. Valente, Silvia Lemma, L. Iommarini, I. Kurelac, P. Memmolo, P. Ferraro
The most recent discoveries in the biochemical field are highlighting the increasingly important role of lipid droplets (LDs) in several regulatory mechanisms in living cells. LDs are dynamic organelles and therefore their complete characterization in terms of number, size, spatial positioning and relative distribution in the cell volume can shed light on the roles played by LDs. Until now, fluorescence microscopy and transmission electron microscopy are assessed as the gold standard methods for identifying LDs due to their high sensitivity and specificity. However, such methods generally only provide 2D assays and partial measurements. Furthermore, both can be destructive and with low productivity, thus limiting analysis of large cell numbers in a sample. Here we demonstrate for the first time the capability of 3D visualization and the full LD characterization in high-throughput with a tomographic phase-contrast flow-cytometer, by using ovarian cancer cells and monocyte cell lines as models. A strategy for retrieving significant parameters on spatial correlations and LD 3D positioning inside each cell volume is reported. The information gathered by this new method could allow more in depth understanding and lead to new discoveries on how LDs are correlated to cellular functions. 3D D. Pirone, P. Memmolo, V. Bianco, L. Iom- marini and P. Ferraro analyzed and discussed the tomographic reconstruc-tions and data. I. Kurelac, S. Lemma and L. Iommarini performed FM ex- periments and data analysis; G. Pasquinelli and S. Valente performed the TEM; all the authors contributed to critical discussion of the results and contributed to write the manuscript. P. Ferraro supervised the research.
生物化学领域的最新发现强调了脂滴(ld)在活细胞的几种调节机制中的重要作用。ld是动态细胞器，因此它们在细胞体积中的数量、大小、空间定位和相对分布方面的完整表征可以揭示ld所起的作用。到目前为止，荧光显微镜和透射电子显微镜因其高灵敏度和特异性被评价为鉴定ld的金标准方法。然而，这种方法通常只提供二维分析和部分测量。此外，两者都具有破坏性且生产率低，因此限制了样品中大量细胞的分析。本文首次以卵巢癌细胞和单核细胞系为模型，利用层析相衬流式细胞仪展示了高通量的3D可视化和全LD表征能力。一种策略，检索显著参数的空间相关性和LD三维定位在每个细胞体积。通过这种新方法收集的信息可以让我们更深入地了解ld如何与细胞功能相关，并导致新的发现。3D D. Pirone, P. Memmolo, V. Bianco, L. Iom- marini和P. Ferraro对层析重建和数据进行了分析和讨论。I. Kurelac、S. Lemma和L. Iommarini进行调频实验和数据分析;G. Pasquinelli和S. Valente进行透射电镜观察;所有作者都参与了对结果的批判性讨论，并参与了论文的撰写。P. Ferraro监督了这项研究。
{"title":"3D imaging lipidometry in single cell by in-flow holographic tomography","authors":"D. Pirone, Daniele G Sirico, L. Miccio, V. Bianco, M. Mugnano, D. D. Giudice, G. Pasquinelli, S. Valente, Silvia Lemma, L. Iommarini, I. Kurelac, P. Memmolo, P. Ferraro","doi":"10.29026/oea.2023.220048","DOIUrl":"https://doi.org/10.29026/oea.2023.220048","url":null,"abstract":"The most recent discoveries in the biochemical field are highlighting the increasingly important role of lipid droplets (LDs) in several regulatory mechanisms in living cells. LDs are dynamic organelles and therefore their complete characterization in terms of number, size, spatial positioning and relative distribution in the cell volume can shed light on the roles played by LDs. Until now, fluorescence microscopy and transmission electron microscopy are assessed as the gold standard methods for identifying LDs due to their high sensitivity and specificity. However, such methods generally only provide 2D assays and partial measurements. Furthermore, both can be destructive and with low productivity, thus limiting analysis of large cell numbers in a sample. Here we demonstrate for the first time the capability of 3D visualization and the full LD characterization in high-throughput with a tomographic phase-contrast flow-cytometer, by using ovarian cancer cells and monocyte cell lines as models. A strategy for retrieving significant parameters on spatial correlations and LD 3D positioning inside each cell volume is reported. The information gathered by this new method could allow more in depth understanding and lead to new discoveries on how LDs are correlated to cellular functions. 3D D. Pirone, P. Memmolo, V. Bianco, L. Iom- marini and P. Ferraro analyzed and discussed the tomographic reconstruc-tions and data. I. Kurelac, S. Lemma and L. Iommarini performed FM ex- periments and data analysis; G. Pasquinelli and S. Valente performed the TEM; all the authors contributed to critical discussion of the results and contributed to write the manuscript. P. Ferraro supervised the research.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69521085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2022-01-01DOI: 10.29026/oea.2022.210045
E. Du, Shuhao Shen, Anqi Qiu, Nanguang Chen
Laser speckle imaging has been widely used for in-vivo visualization of blood perfusion in biological tissues. However, existing laser speckle imaging techniques suffer from limited quantification accuracy and spatial resolution. Here we report a novel design and implementation of a powerful laser speckle imaging platform to solve the two critical limitations. The core technique of our platform is a combination of line scan confocal microscopy with laser speckle autocorrelation imaging, which is termed Line Scan Laser Speckle Autocorrelation Imaging (LS-LSAI). The technical advantages of LS-LSAI include high spatial resolution (~4.4 μm) for visualizing and quantifying blood flow in microvessels, as well as video-rate imaging speed for tracing dynamic flow
{"title":"Confocal laser speckle autocorrelation imaging of dynamic flow in microvasculature","authors":"E. Du, Shuhao Shen, Anqi Qiu, Nanguang Chen","doi":"10.29026/oea.2022.210045","DOIUrl":"https://doi.org/10.29026/oea.2022.210045","url":null,"abstract":"Laser speckle imaging has been widely used for in-vivo visualization of blood perfusion in biological tissues. However, existing laser speckle imaging techniques suffer from limited quantification accuracy and spatial resolution. Here we report a novel design and implementation of a powerful laser speckle imaging platform to solve the two critical limitations. The core technique of our platform is a combination of line scan confocal microscopy with laser speckle autocorrelation imaging, which is termed Line Scan Laser Speckle Autocorrelation Imaging (LS-LSAI). The technical advantages of LS-LSAI include high spatial resolution (~4.4 μm) for visualizing and quantifying blood flow in microvessels, as well as video-rate imaging speed for tracing dynamic flow","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69516605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2022-01-01DOI: 10.29026/oea.2022.210062
Jitao Li, Guo-cui Wang, Zhen Yue, Jingyu Liu, Jie Li, Chenglong Zheng, Yating Zhang, Yan Zhang, Jianquan Yao
If a metalens integrates the circular polarization (CP) conversion function, the focusing lens together with circular-polariz-ing lens (CPL) in traditional cameras may be replaced by a metalens. However, in terahertz (THz) band, the reported metalenses still do not obtain the perfect and strict single-handed CP, because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP (LCP) and right-handed CP (RCP) components. In this paper, a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion. Also, we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states, which can simply manipulate the focusing for incident linear polarization (LP) THz wave in three polarization conversion states, including LP without conversion, LCP and RCP. Moreover, the polarization conversion behavior is reversible, that is, the THz metalens can convert not only the LP into arbitrary single-handed CP, but also the LCP and RCP into two perpendicular LP, respectively. The metalens is expected to be used in advanced THz camera, as a great candidate for traditional CPL and focusing lens group, and also shows potential application in polarization imaging with discriminating LCP and RCP.
{"title":"Dynamic phase assembled terahertz metalens for reversible conversion between linear polarization and arbitrary circular polarization","authors":"Jitao Li, Guo-cui Wang, Zhen Yue, Jingyu Liu, Jie Li, Chenglong Zheng, Yating Zhang, Yan Zhang, Jianquan Yao","doi":"10.29026/oea.2022.210062","DOIUrl":"https://doi.org/10.29026/oea.2022.210062","url":null,"abstract":"If a metalens integrates the circular polarization (CP) conversion function, the focusing lens together with circular-polariz-ing lens (CPL) in traditional cameras may be replaced by a metalens. However, in terahertz (THz) band, the reported metalenses still do not obtain the perfect and strict single-handed CP, because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP (LCP) and right-handed CP (RCP) components. In this paper, a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion. Also, we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states, which can simply manipulate the focusing for incident linear polarization (LP) THz wave in three polarization conversion states, including LP without conversion, LCP and RCP. Moreover, the polarization conversion behavior is reversible, that is, the THz metalens can convert not only the LP into arbitrary single-handed CP, but also the LCP and RCP into two perpendicular LP, respectively. The metalens is expected to be used in advanced THz camera, as a great candidate for traditional CPL and focusing lens group, and also shows potential application in polarization imaging with discriminating LCP and RCP.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69517955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-12-31DOI: 10.29026/oea.2022.210086
J. Maksimovic, Jingwen Hu, S. Ng, T. Katkus, G. Seniutinas, T. P. Rivera, M. Stuiber, Y. Nishijima, S. John, S. Juodkazis
Light trapping photonic crystal (PhC) patterns on the surface of Si solar cells provides a novel opportunity to approach the theoretical efficiency limit of 32.3%, for light-to-electrical power conversion with a single junction cell. This is beyond the efficiency limit implied by the Lambertian limit of ray trapping 29%. The interference and slow light effects are harnessed for collecting light even at the long wavelengths near the Si band-gap. We compare two different methods for surface patterning, that can be extended to large area surface patterning: 1) laser direct write and 2) step-&-repeat 5-times reduction projection lithography. Large area throughput limitations of these methods are compared with the established electron beam lithography (EBL) route, which is conventionally utilised but much slower than the presented methods. Spectral characterisation of the PhC light trapping is compared for samples fabricated by different methods. Reflectance of Si etched via laser patterned mask was 7% at visible wavelengths and was comparable with Si patterned via EBL made mask. The later pattern showed a stronger absorbance than the Lambertian limit (M.-L. Hsieh et al., Sci. Rep. 10, 11857 (2020)).
{"title":"Beyond Lambertian light trapping for large-area silicon solar cells: fabrication methods","authors":"J. Maksimovic, Jingwen Hu, S. Ng, T. Katkus, G. Seniutinas, T. P. Rivera, M. Stuiber, Y. Nishijima, S. John, S. Juodkazis","doi":"10.29026/oea.2022.210086","DOIUrl":"https://doi.org/10.29026/oea.2022.210086","url":null,"abstract":"Light trapping photonic crystal (PhC) patterns on the surface of Si solar cells provides a novel opportunity to approach the theoretical efficiency limit of 32.3%, for light-to-electrical power conversion with a single junction cell. This is beyond the efficiency limit implied by the Lambertian limit of ray trapping 29%. The interference and slow light effects are harnessed for collecting light even at the long wavelengths near the Si band-gap. We compare two different methods for surface patterning, that can be extended to large area surface patterning: 1) laser direct write and 2) step-&-repeat 5-times reduction projection lithography. Large area throughput limitations of these methods are compared with the established electron beam lithography (EBL) route, which is conventionally utilised but much slower than the presented methods. Spectral characterisation of the PhC light trapping is compared for samples fabricated by different methods. Reflectance of Si etched via laser patterned mask was 7% at visible wavelengths and was comparable with Si patterned via EBL made mask. The later pattern showed a stronger absorbance than the Lambertian limit (M.-L. Hsieh et al., Sci. Rep. 10, 11857 (2020)).","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46399163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-12-13DOI: 10.29026/oea.2022.210105
C. S. Saraj, S. Singh, Gopal Verma, R. Rajan, Wei Li, Chunlei Guo
Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generate fuels. These reactions, however, suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst. A large electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites, but this comes at the cost of electricity. Here, we report about 45 % saving in energy to achieve an electrochemical hydrogen generation rate of 3×1016 molecules cm-2s-1 (current density: 10 mA/cm2) through localized electric field-induced enhancement in the reagent concentration (LEFIRC) at laser-induced periodic surface structured (LIPSS) electrodes. The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization. When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO2 electrocatalysts, the 10 overpotentials for HER and OER are decreased by 40 and 25 %, respectively. Moreover, the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes including alkaline, acidic, neutral, and seawater. Importantly, when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell, it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm2. This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.
{"title":"Laser-induced periodic surface structured electrodes with 45% energy saving in electrochemical fuel generation through field localization","authors":"C. S. Saraj, S. Singh, Gopal Verma, R. Rajan, Wei Li, Chunlei Guo","doi":"10.29026/oea.2022.210105","DOIUrl":"https://doi.org/10.29026/oea.2022.210105","url":null,"abstract":"Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generate fuels. These reactions, however, suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst. A large electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites, but this comes at the cost of electricity. Here, we report about 45 % saving in energy to achieve an electrochemical hydrogen generation rate of 3×1016 molecules cm-2s-1 (current density: 10 mA/cm2) through localized electric field-induced enhancement in the reagent concentration (LEFIRC) at laser-induced periodic surface structured (LIPSS) electrodes. The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization. When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO2 electrocatalysts, the 10 overpotentials for HER and OER are decreased by 40 and 25 %, respectively. Moreover, the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes including alkaline, acidic, neutral, and seawater. Importantly, when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell, it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm2. This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44786068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-10-22DOI: 10.29026/oea.2022.210147
S. Krasikov, Aaron D Tranter, A. Bogdanov, Y. Kivshar
In the recent years, we observe a dramatic boost of research in photonics empowered by the concepts of machine learning and artificial intelligence. The corresponding photonic systems, to which this new methodology is applied, can range from traditional optical waveguides to nanoantennas and metasurfaces, and these novel approaches underpin the fundamental principles of light-matter interaction developed for a smart design of intelligent photonic devices. Concepts and approaches of artificial intelligence and machine learning penetrate rapidly into the fundamental physics of light, and they provide effective tools for the study of the field of metaphotonics driven by optically-induced electric and magnetic resonances. Here, we introduce this new field with its application to metaphotonics and also present a summary of the basic concepts of machine learning with some specific examples developed and demonstrated for metasystems and metasurfaces.
{"title":"Intelligent metaphotonics empowered by machine learning","authors":"S. Krasikov, Aaron D Tranter, A. Bogdanov, Y. Kivshar","doi":"10.29026/oea.2022.210147","DOIUrl":"https://doi.org/10.29026/oea.2022.210147","url":null,"abstract":"In the recent years, we observe a dramatic boost of research in photonics empowered by the concepts of machine learning and artificial intelligence. The corresponding photonic systems, to which this new methodology is applied, can range from traditional optical waveguides to nanoantennas and metasurfaces, and these novel approaches underpin the fundamental principles of light-matter interaction developed for a smart design of intelligent photonic devices. Concepts and approaches of artificial intelligence and machine learning penetrate rapidly into the fundamental physics of light, and they provide effective tools for the study of the field of metaphotonics driven by optically-induced electric and magnetic resonances. Here, we introduce this new field with its application to metaphotonics and also present a summary of the basic concepts of machine learning with some specific examples developed and demonstrated for metasystems and metasurfaces.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2021-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42449748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-04-27DOI: 10.29026/oea.2022.210052
F. Fraggelakis, G. Tsibidis, E. Stratakis
We present a novel approach for tailoring the laser induced surface topography upon femtosecond (fs) pulsed laser irradiation. The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation. The pulse train used, in particular, consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning (DLIP). The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow, while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained. Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies. The underlying physical processes behind the complex patterns’ generation were interpreted in terms of a multiscale model combining electrodynamic excitation with melt hydrodynamics. We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.
{"title":"Ultrashort pulsed laser induced complex surface structures generated by tailoring the melt hydrodynamics","authors":"F. Fraggelakis, G. Tsibidis, E. Stratakis","doi":"10.29026/oea.2022.210052","DOIUrl":"https://doi.org/10.29026/oea.2022.210052","url":null,"abstract":"We present a novel approach for tailoring the laser induced surface topography upon femtosecond (fs) pulsed laser irradiation. The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation. The pulse train used, in particular, consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning (DLIP). The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow, while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained. Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies. The underlying physical processes behind the complex patterns’ generation were interpreted in terms of a multiscale model combining electrodynamic excitation with melt hydrodynamics. We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2021-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44890379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-04-22DOI: 10.29026/oea.2022.210014
Yudong Lu, Yi Xu, Ouyang Xu, Mingcong Xian, Yaoyu Cao, Kai Chen, Xiangping Li
Nonscattering optical anapole condition is corresponding to the excitation of radiationless field distributions in open resonators, which offers new degrees of freedom for tailoring light-matter interaction. Conventional mechanisms for achieving such a condition relies on sophisticated manipulation of electromagnetic multipolar moments of all orders to guarantee superpositions of vanished moment strengths at the same wavelength. In contrast, here we report on the excitation of optical radiationless anapole hidden in a resonant state of a Si nanoparticle utilizing tightly focused radially polarized (RP) beam. The coexistence of magnetic resonant state and anapole condition at the same wavelength further enables the triggering of resonant state by tightly focused azimuthally polarized (AP) beam whose corresponding electric multipole coefficient could be zero. As a result, high contrast inter-transition between radiationless anapole condition and ideal magnetic resonant scattering can be achieved experimentally in visible spectrum. The proposed mechanism is general which can be realized in different types of nanostructures. Our results showcase that the unique combination of structured light and structured Mie resonances could provide new degrees of freedom for tailoring light-matter interaction, which might shed new light on functional meta-optics.
{"title":"Cylindrical vector beams reveal radiationless anapole condition in a resonant state","authors":"Yudong Lu, Yi Xu, Ouyang Xu, Mingcong Xian, Yaoyu Cao, Kai Chen, Xiangping Li","doi":"10.29026/oea.2022.210014","DOIUrl":"https://doi.org/10.29026/oea.2022.210014","url":null,"abstract":"Nonscattering optical anapole condition is corresponding to the excitation of radiationless field distributions in open resonators, which offers new degrees of freedom for tailoring light-matter interaction. Conventional mechanisms for achieving such a condition relies on sophisticated manipulation of electromagnetic multipolar moments of all orders to guarantee superpositions of vanished moment strengths at the same wavelength. In contrast, here we report on the excitation of optical radiationless anapole hidden in a resonant state of a Si nanoparticle utilizing tightly focused radially polarized (RP) beam. The coexistence of magnetic resonant state and anapole condition at the same wavelength further enables the triggering of resonant state by tightly focused azimuthally polarized (AP) beam whose corresponding electric multipole coefficient could be zero. As a result, high contrast inter-transition between radiationless anapole condition and ideal magnetic resonant scattering can be achieved experimentally in visible spectrum. The proposed mechanism is general which can be realized in different types of nanostructures. Our results showcase that the unique combination of structured light and structured Mie resonances could provide new degrees of freedom for tailoring light-matter interaction, which might shed new light on functional meta-optics.","PeriodicalId":19611,"journal":{"name":"Opto-Electronic Advances","volume":null,"pages":null},"PeriodicalIF":14.1,"publicationDate":"2021-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45493814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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