Pub Date : 2025-04-19DOI: 10.1016/j.photonics.2025.101388
Anjineya K , Don Mathew , Meghna C.H , Vincent Mathew
This work proposes a refractive index sensor designed with a 1D (One-dimensional) topological photonic crystal by merging two 1D photonic crystals, which differ topologically, and introducing a defect layer at the interface of these two photonic crystals. It is designed by finding and analyzing the Zak phase of the photonic crystals, and the results ensure increased sensitivity and quality factor, with the highest figure of merit of 29383.759(RIU−1). The topologically protected edge state is used for sensing, which guarantees well-defined peaks with sufficient shifts in wavelength even for a minuscule change in analyte refractive index. The change in sensitivity, quality factor, and figure of merit is studied, and the response to the change in the refractive index is impressive.
{"title":"Analysis of refractive index sensor using topological photonic protected edge state in one-dimensional photonic crystal","authors":"Anjineya K , Don Mathew , Meghna C.H , Vincent Mathew","doi":"10.1016/j.photonics.2025.101388","DOIUrl":"10.1016/j.photonics.2025.101388","url":null,"abstract":"<div><div>This work proposes a refractive index sensor designed with a 1D (One-dimensional) topological photonic crystal by merging two 1D photonic crystals, which differ topologically, and introducing a defect layer at the interface of these two photonic crystals. It is designed by finding and analyzing the Zak phase of the photonic crystals, and the results ensure increased sensitivity and quality factor, with the highest figure of merit of 29383.759(<em>RIU</em><sup>−1</sup>). The topologically protected edge state is used for sensing, which guarantees well-defined peaks with sufficient shifts in wavelength even for a minuscule change in analyte refractive index. The change in sensitivity, quality factor, and figure of merit is studied, and the response to the change in the refractive index is impressive.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"65 ","pages":"Article 101388"},"PeriodicalIF":2.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-18DOI: 10.1016/j.photonics.2025.101389
Chengchao Wang , Haojun Zhu , Hengyi Fan , Yinmo Xie , Qingzhi Lai , Lanxin Ma
Nanocomposite films based on Cesium tungsten oxide (CWO) and Indium tin oxide (ITO) nanoparticles provide a broad space for adjusting the optical properties of energy-saving windows due to their unique near-infrared absorption properties. This property has led to great research interest in the field of energy-saving windows for such materials. The optical properties of energy-saving windows are mainly determined by localized surface plasmon resonance (LSPR) of the nanoparticles, and thus they are sensitive to the variation of the geometrical parameters of the nanoparticles. Typically, the computational cost of the design of specific optical properties and iterative optimization of the geometrical parameters is expensive and time-consuming. In this study, we combine machine learning and radiative transfer calculations to achieve targeted design energy-saving windows. By adjusting the shape, material, and geometric parameters of nanoparticles, an analysis model can be established from the geometric parameters of nanoparticles to the properties of energy-saving windows. Then, a machine learning model of bidirectional deep neural network is developed to achieve accurate prediction of optical evaluation parameters (visible transmittance (Tlum), near-infrared (NIR) transmittance (TNIR), solar radiation transmittance (Tsol), and the Figure of Merit (FOM)) for energy-saving windows, as well as inverse design of geometric parameters of nanoparticles (CWO and ITO). The results indicate that our machine learning model achieved forward prediction of energy-saving window optical properties with an accuracy of over 99 % and inverse geometric parameter design with an accuracy of over 93 %. Overall, this work provides a broadly appropriate and computationally efficient method for evaluating and designing the properties of energy-saving windows.
{"title":"Machine-learning-assisted design of energy-saving windows with high near-infrared shielding properties","authors":"Chengchao Wang , Haojun Zhu , Hengyi Fan , Yinmo Xie , Qingzhi Lai , Lanxin Ma","doi":"10.1016/j.photonics.2025.101389","DOIUrl":"10.1016/j.photonics.2025.101389","url":null,"abstract":"<div><div>Nanocomposite films based on Cesium tungsten oxide (CWO) and Indium tin oxide (ITO) nanoparticles provide a broad space for adjusting the optical properties of energy-saving windows due to their unique near-infrared absorption properties. This property has led to great research interest in the field of energy-saving windows for such materials. The optical properties of energy-saving windows are mainly determined by localized surface plasmon resonance (LSPR) of the nanoparticles, and thus they are sensitive to the variation of the geometrical parameters of the nanoparticles. Typically, the computational cost of the design of specific optical properties and iterative optimization of the geometrical parameters is expensive and time-consuming. In this study, we combine machine learning and radiative transfer calculations to achieve targeted design energy-saving windows. By adjusting the shape, material, and geometric parameters of nanoparticles, an analysis model can be established from the geometric parameters of nanoparticles to the properties of energy-saving windows. Then, a machine learning model of bidirectional deep neural network is developed to achieve accurate prediction of optical evaluation parameters (visible transmittance (<em>T</em><sub>lum</sub>), near-infrared (NIR) transmittance (<em>T</em><sub>NIR</sub>), solar radiation transmittance (<em>T</em><sub>sol</sub>), and the Figure of Merit (<em>FOM</em>)) for energy-saving windows, as well as inverse design of geometric parameters of nanoparticles (CWO and ITO). The results indicate that our machine learning model achieved forward prediction of energy-saving window optical properties with an accuracy of over 99 % and inverse geometric parameter design with an accuracy of over 93 %. Overall, this work provides a broadly appropriate and computationally efficient method for evaluating and designing the properties of energy-saving windows.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"65 ","pages":"Article 101389"},"PeriodicalIF":2.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Efforts were done to enhance the nonlinear optical and optical power limiting responses of Indole-7-carboxaldehyde (I7C) after the addition of silver and gold nanoparticles. The investigations were done theoretically as well as experimentally. The reactivity parameters and potential surfaces established strong intermolecular charge interactions between metal trimer and I7C. The diffraction pattern for both I7C+AgNPs and I7C+AuNPs indicated the perfect crystallinity of the samples. The band gap of I7C+AgNPs (2.08 eV) was less than that of I7C+AuNPs (2.34 eV). The polarizability of I7C was enhanced after the addition of gold and silver nanoparticles. The value of first-order hyperpolarizability of probe I7C was observed as 4.24 × 10−30 esu which was increased to ten times for I7C+AgNPs and eighteen times for I7C+AuNPs. The increased value of first-order hyperpolarizability supported enhanced nonlinear optical characteristics of I7C+AgNPs and I7C+AuNPs. Further, the reduction in experimentally obtained optical limiting threshold and increment in the nonlinear absorption coefficient reflects early attenuation of the nonlinear optical and enhanced optical limiting activity of I7C+AgNPs and I7C+AuNPs.
{"title":"Indole-7-carboxaldehyde functionalized silver and gold nanoparticles as novel metal-organic laser power limiting composites","authors":"Shradha Lakhera , Meenakshi Rana , A. Dhanusha , T.C. Sabari Girisun , Shruti Sharma , Papia Chowdhury","doi":"10.1016/j.photonics.2025.101386","DOIUrl":"10.1016/j.photonics.2025.101386","url":null,"abstract":"<div><div>Efforts were done to enhance the nonlinear optical and optical power limiting responses of Indole-7-carboxaldehyde (I7C) after the addition of silver and gold nanoparticles. The investigations were done theoretically as well as experimentally. The reactivity parameters and potential surfaces established strong intermolecular charge interactions between metal trimer and I7C. The diffraction pattern for both I7C+AgNPs and I7C+AuNPs indicated the perfect crystallinity of the samples. The band gap of I7C+AgNPs (2.08 eV) was less than that of I7C+AuNPs (2.34 eV). The polarizability of I7C was enhanced after the addition of gold and silver nanoparticles. The value of first-order hyperpolarizability of probe I7C was observed as 4.24 × 10<sup>−30</sup> esu which was increased to ten times for I7C+AgNPs and eighteen times for I7C+AuNPs. The increased value of first-order hyperpolarizability supported enhanced nonlinear optical characteristics of I7C+AgNPs and I7C+AuNPs. Further, the reduction in experimentally obtained optical limiting threshold and increment in the nonlinear absorption coefficient reflects early attenuation of the nonlinear optical and enhanced optical limiting activity of I7C+AgNPs and I7C+AuNPs.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101386"},"PeriodicalIF":2.5,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-02DOI: 10.1016/j.photonics.2025.101385
Varvara Kharitonova , Anastasia Lubimova , Valentin A. Milichko , Semyon V. Bachinin
The development of electro-optical computing systems today is proceeding at an unprecedented pace and requires the emergence of new approaches and materials for data recording and storage. Here we report on a direct laser writing (DLW) of binary data on a surface of metal-organic framework (MOF) thin film over 0.5 s with 1.5 μm resolution. The data, expressed as locally modified areas of different depth and potential, are analyzed with atomic force microscopy in Kelvin-probe regime. We reveal that an increase in laser power yields an increase in the potential of the modified area up to 100 mV (compared with 10 mV for the initial MOF surface) and decrease of the area diameter up to 1.5 μm. The mechanism of DLW is also investigated with confocal Raman spectroscopy, confirming the local modification of the structure of MOF thin film. The results, thereby, open the way for fast optical writing of electronic data with compatible density on MOFs at ambient conditions.
{"title":"Direct laser writing of binary data on metal-organic framework surface","authors":"Varvara Kharitonova , Anastasia Lubimova , Valentin A. Milichko , Semyon V. Bachinin","doi":"10.1016/j.photonics.2025.101385","DOIUrl":"10.1016/j.photonics.2025.101385","url":null,"abstract":"<div><div>The development of electro-optical computing systems today is proceeding at an unprecedented pace and requires the emergence of new approaches and materials for data recording and storage. Here we report on a direct laser writing (DLW) of binary data on a surface of metal-organic framework (MOF) thin film over 0.5 s with 1.5 μm resolution. The data, expressed as locally modified areas of different depth and potential, are analyzed with atomic force microscopy in Kelvin-probe regime. We reveal that an increase in laser power yields an increase in the potential of the modified area up to 100 mV (compared with 10 mV for the initial MOF surface) and decrease of the area diameter up to 1.5 μm. The mechanism of DLW is also investigated with confocal Raman spectroscopy, confirming the local modification of the structure of MOF thin film. The results, thereby, open the way for fast optical writing of electronic data with compatible density on MOFs at ambient conditions.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101385"},"PeriodicalIF":2.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-31DOI: 10.1016/j.photonics.2025.101384
Mikhail Astafurov , Elena Perevedentseva , Nikolay Melnik , Mikhail Shevchenko , Sergey Dorofeev , Alexander Ezhov , Daniil Kozlov , Anastasia Grigorieva , Sergey Klimonsky
Bilayer opal-type stripes periodically arranged on the same substrate were self-assembled using the vertical deposition of SiO2 spheres with the intermittent motion of the meniscus. It has been shown that each such stripe with a gold or silver coating can be considered as an independent element for surface enhanced Raman scattering (SERS). The thicknesses of the gold and silver coatings were optimized using computer simulations of electromagnetic field enhancement. Monolayer or bilayer stripes of such type are not inferior to thick opal films with noble metal coating. The stripe patterned structures are easy to manufacture, exhibit good homogeneity and may be promising for automating multiple SERS tests. The structures with gold coating also demonstrate high resistance to environmental influences. The prospects for further improvement of their properties were analyzed.
{"title":"SERS in opal-type stripe patterned structures with metal coating","authors":"Mikhail Astafurov , Elena Perevedentseva , Nikolay Melnik , Mikhail Shevchenko , Sergey Dorofeev , Alexander Ezhov , Daniil Kozlov , Anastasia Grigorieva , Sergey Klimonsky","doi":"10.1016/j.photonics.2025.101384","DOIUrl":"10.1016/j.photonics.2025.101384","url":null,"abstract":"<div><div>Bilayer opal-type stripes periodically arranged on the same substrate were self-assembled using the vertical deposition of SiO<sub>2</sub> spheres with the intermittent motion of the meniscus. It has been shown that each such stripe with a gold or silver coating can be considered as an independent element for surface enhanced Raman scattering (SERS). The thicknesses of the gold and silver coatings were optimized using computer simulations of electromagnetic field enhancement. Monolayer or bilayer stripes of such type are not inferior to thick opal films with noble metal coating. The stripe patterned structures are easy to manufacture, exhibit good homogeneity and may be promising for automating multiple SERS tests. The structures with gold coating also demonstrate high resistance to environmental influences. The prospects for further improvement of their properties were analyzed.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101384"},"PeriodicalIF":2.5,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-18DOI: 10.1016/j.photonics.2025.101383
Renjie Li , Yanze Gao , Weijie Liu , Tongtong An , Hongcheng Pan , Yuan Mu , Xujin Yuan
The photo-thermo-acoustic (PTA) effect of a three-layer composite material whose surface is fabricated with many periodic micro-nano structures (PMNS) is investigated in this paper. The material is composed of a silicon substrate, a thermal insulation layer of polyimide, and a light-absorbing layer of aluminum nanoaggregates. We propose a method for analyzing the PTA effect based on the idea of finite element meshing. The PTA conversion processes including the photo-thermal conversion and the thermal-acoustic conversion are quantitatively simulated. The influence of the geometric parameters of the PMNS on the intensity and space distribution of the sound field is analyzed both by simulation and experiment. The results show that fabricating PMNS on composite materials can significantly enhance the PTA effect. And the finite element analyzing method proposed in this paper can correctly describe and predict the PTA effect of composite materials with two-dimensional PMNS. It is also applicable for analyzing the PTA effects of other similar materials or structures.
{"title":"Photo-thermo-acoustic (PTA) effect of a multilayer composite material with periodic micro-nano structures (PMNS): Modeling, simulation and experiment","authors":"Renjie Li , Yanze Gao , Weijie Liu , Tongtong An , Hongcheng Pan , Yuan Mu , Xujin Yuan","doi":"10.1016/j.photonics.2025.101383","DOIUrl":"10.1016/j.photonics.2025.101383","url":null,"abstract":"<div><div>The photo-thermo-acoustic (PTA) effect of a three-layer composite material whose surface is fabricated with many periodic micro-nano structures (PMNS) is investigated in this paper. The material is composed of a silicon substrate, a thermal insulation layer of polyimide, and a light-absorbing layer of aluminum nanoaggregates. We propose a method for analyzing the PTA effect based on the idea of finite element meshing. The PTA conversion processes including the photo-thermal conversion and the thermal-acoustic conversion are quantitatively simulated. The influence of the geometric parameters of the PMNS on the intensity and space distribution of the sound field is analyzed both by simulation and experiment. The results show that fabricating PMNS on composite materials can significantly enhance the PTA effect. And the finite element analyzing method proposed in this paper can correctly describe and predict the PTA effect of composite materials with two-dimensional PMNS. It is also applicable for analyzing the PTA effects of other similar materials or structures.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101383"},"PeriodicalIF":2.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-17DOI: 10.1016/j.photonics.2025.101382
Abdulkadir Cildir , Farooq A. Tahir , Muhammad Farooq , Adnan Zahid , Muhammad Imran , Qammer H. Abbasi
This research paper introduces a new design of metasurface for polarization conversion applications, functioning as both a cross (half-wave plate) and circular (quarter wave plate) polarizer in reflection mode. Comprising unit cells on one side and a metal layer on the other, with a Roger 5880 substrate, the metasurface demonstrates its ability to reflect an incident - or -polarized wave as a - or -polarized wave across multiple frequency bands: 9.72–10.00 GHz, 17.65–41.87 GHz, 45.67–45.80 GHz, and 49.66–49.84 GHz. The design achieves a noteworthy 24.82 GHz bandwidth with a 98.72 % fractional bandwidth for linear-to-linear conversion, demonstrating efficiency exceeding 90 %. Simultaneously, the metasurface converts the incident wave into a right-hand circularly polarized (RHCP) wave at frequencies ranging from 9.38 to 9.61 GHz, 45.9–46.1 GHz, and 49.96–50 GHz. It transforms the wave into a left-hand circularly polarized (LHCP) wave within the frequency band from 10.19 to 10.61 GHz, 15.60–16.82 GHz, and 45.45–45.6 GHz. The design also exhibits angular stability up to 45 degrees. Experimental validation using the fabricated prototype confirms the findings, showing good agreement with numerical results. This metasurface comes in handy for future communication, radar application, and health applications. This metasurface is highly suitable for future communication systems, radar applications, and healthcare technologies.
{"title":"A highly efficient and broadband metasurface for linear-to-linear and linear-to-circular polarization conversion in reflection mode","authors":"Abdulkadir Cildir , Farooq A. Tahir , Muhammad Farooq , Adnan Zahid , Muhammad Imran , Qammer H. Abbasi","doi":"10.1016/j.photonics.2025.101382","DOIUrl":"10.1016/j.photonics.2025.101382","url":null,"abstract":"<div><div>This research paper introduces a new design of metasurface for polarization conversion applications, functioning as both a cross (half-wave plate) and circular (quarter wave plate) polarizer in reflection mode. Comprising unit cells on one side and a metal layer on the other, with a Roger 5880 substrate, the metasurface demonstrates its ability to reflect an incident <span><math><mi>x</mi></math></span>- or <span><math><mi>y</mi></math></span>-polarized wave as a <span><math><mi>y</mi></math></span>- or <span><math><mi>x</mi></math></span>-polarized wave across multiple frequency bands: 9.72–10.00 GHz, 17.65–41.87 GHz, 45.67–45.80 GHz, and 49.66–49.84 GHz. The design achieves a noteworthy 24.82 GHz bandwidth with a 98.72 % fractional bandwidth for linear-to-linear conversion, demonstrating efficiency exceeding 90 %. Simultaneously, the metasurface converts the incident wave into a right-hand circularly polarized (RHCP) wave at frequencies ranging from 9.38 to 9.61 GHz, 45.9–46.1 GHz, and 49.96–50 GHz. It transforms the wave into a left-hand circularly polarized (LHCP) wave within the frequency band from 10.19 to 10.61 GHz, 15.60–16.82 GHz, and 45.45–45.6 GHz. The design also exhibits angular stability up to 45 degrees. Experimental validation using the fabricated prototype confirms the findings, showing good agreement with numerical results. This metasurface comes in handy for future communication, radar application, and health applications. This metasurface is highly suitable for future communication systems, radar applications, and healthcare technologies.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101382"},"PeriodicalIF":2.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-17DOI: 10.1016/j.photonics.2025.101381
Mahesh Valathuru , Pokkunuri Pardhasaradhi , Nagandla Prasad , Boddapati Taraka Phani Madhav , Sudipta Das , Abeer D. Algarni , Mohammed El Ghzaoui
This research proposes an ultra-broadband terahertz absorber (UBTA) employing a metamaterial (MTM) structure based on vanadium dioxide (VO2). The top layer of the suggested MTM-UBTA model is made up of VO2 that is 0.2 µm thick, the bottom layer is made up of 3 µm thick gold material, and the middle layer is made up of silicon dioxide (SiO2) dielectric material of 7 µm thickness. The simulation results indicate an absorption bandwidth of 4.1 THz, from 2.8 to 6.9 THz, obtained under normal incidence. The suggested absorber maintains absorption above 92 % over a broad operating wavelength of 43.44 μm to 107.06 μm. The main goal of this study is to look into THz metamaterial absorbers based on VO2 in great detail, including every facet of their design validation and hys RevL through an ECM (Equivalent Circuit Model) approach. Furthermore, the impact of incident and polarization angle on absorbance for TE and TM modes is discussed and polarization insensitivity is verified. The prescribed MTM-ultra-broadband terahertz absorber is suitable for intelligent absorption, terahertz tuning, modulation, cloaking, optic-electro switching, biological sensing, and stealth technology.
{"title":"Design and analysis of metamaterial-based ultra-broadband micro-scaled absorber with vanadium dioxide (VO2) and silicon dioxide (SiO2) for multiple terahertz applications","authors":"Mahesh Valathuru , Pokkunuri Pardhasaradhi , Nagandla Prasad , Boddapati Taraka Phani Madhav , Sudipta Das , Abeer D. Algarni , Mohammed El Ghzaoui","doi":"10.1016/j.photonics.2025.101381","DOIUrl":"10.1016/j.photonics.2025.101381","url":null,"abstract":"<div><div>This research proposes an ultra-broadband terahertz absorber (UBTA) employing a metamaterial (MTM) structure based on vanadium dioxide (VO<sub>2</sub>). The top layer of the suggested MTM-UBTA model is made up of VO<sub>2</sub> that is 0.2 µm thick, the bottom layer is made up of 3 µm thick gold material, and the middle layer is made up of silicon dioxide (SiO<sub>2</sub>) dielectric material of 7 µm thickness. The simulation results indicate an absorption bandwidth of 4.1 THz, from 2.8 to 6.9 THz, obtained under normal incidence. The suggested absorber maintains absorption above 92 % over a broad operating wavelength of 43.44 μm to 107.06 μm. The main goal of this study is to look into THz metamaterial absorbers based on VO<sub>2</sub> in great detail, including every facet of their design validation and hys RevL through an ECM (Equivalent Circuit Model) approach. Furthermore, the impact of incident and polarization angle on absorbance for TE and TM modes is discussed and polarization insensitivity is verified. The prescribed MTM-ultra-broadband terahertz absorber is suitable for intelligent absorption, terahertz tuning, modulation, cloaking, optic-electro switching, biological sensing, and stealth technology.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101381"},"PeriodicalIF":2.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-12DOI: 10.1016/j.photonics.2025.101379
Omar A.M. Abdelraouf , Ahmed Mousa , Mohamed Ragab
Metasurfaces are crucial in advancing flat optics and nanophotonics, offering unique advantages in creating vibrant structural colors and high-Q factor cavities. Multi-layer metasurfaces (MLMs) take this further by enhancing light-matter interactions inside the single meta-atom at the nanoscale. However, optimizing MLM designs is challenging due to the complex interplay of many parameters, making traditional simulation methods slow and inefficient. In this work, we introduce NanoPhotoNet, an advanced AI-powered design tool that leverages a hybrid deep neural network (DNN) combining convolutional neural networks (CNN) and Long Short-Term Memory (LSTM) models. NanoPhotoNet significantly accelerates the design process for MLMs, achieving over 98.3 % prediction accuracy and a 50,000x speed improvement compared to conventional techniques. This enables the creation of structural colors far beyond the standard RGB range, increasing the RGB gamut area up to 163 %. Additionally, NanoPhotoNet facilitates tunable color generation, extending the capabilities of MLMs to advanced applications like tunable color filters, nanolasers, and reconfigurable beam steering. This approach represents a transformative progress in metasurface design, unlocking new possibilities for high-performance, tunable nanophotonic devices.
{"title":"NanoPhotoNet: AI-enhanced design tool for reconfigurable and high-performance multi-layer metasurfaces","authors":"Omar A.M. Abdelraouf , Ahmed Mousa , Mohamed Ragab","doi":"10.1016/j.photonics.2025.101379","DOIUrl":"10.1016/j.photonics.2025.101379","url":null,"abstract":"<div><div>Metasurfaces are crucial in advancing flat optics and nanophotonics, offering unique advantages in creating vibrant structural colors and high-Q factor cavities. Multi-layer metasurfaces (MLMs) take this further by enhancing light-matter interactions inside the single meta-atom at the nanoscale. However, optimizing MLM designs is challenging due to the complex interplay of many parameters, making traditional simulation methods slow and inefficient. In this work, we introduce NanoPhotoNet, an advanced AI-powered design tool that leverages a hybrid deep neural network (DNN) combining convolutional neural networks (CNN) and Long Short-Term Memory (LSTM) models. NanoPhotoNet significantly accelerates the design process for MLMs, achieving over 98.3 % prediction accuracy and a 50,000x speed improvement compared to conventional techniques. This enables the creation of structural colors far beyond the standard RGB range, increasing the RGB gamut area up to 163 %. Additionally, NanoPhotoNet facilitates tunable color generation, extending the capabilities of MLMs to advanced applications like tunable color filters, nanolasers, and reconfigurable beam steering. This approach represents a transformative progress in metasurface design, unlocking new possibilities for high-performance, tunable nanophotonic devices.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101379"},"PeriodicalIF":2.5,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-efficiency and highly integrated optical switches in integrated photonic circuits have long been a pursuit for researchers. Due to the inherent limitations of silicon materials and fabrication processes, commonly used resonant or interferometric optical switches typically require tens to hundreds of micrometers of footprint to achieve desirable modulation efficiency. In response, we propose an optical switch structure filled with phase-change material (PCM) in a narrow slit, with tapered waveguides on curved sides coupling light in and out of the slit, enabling strong light-matter interaction. This structure consists of curved-side tapered coupling waveguides at both ends and a slit filled with GST (Ge2Sb2Te5) in the middle. By applying an external stimulus to induce a phase change in the GST, which exhibits significant differences in optical properties between its crystalline and amorphous states, substantial modulation efficiency can be achieved. Operating in the transverse electric mode within the band of 1500–1600 nm, this structure can achieve an extinction ratio (ER) of 34.08 dB and an insertion loss (IL) of 0.18 dB at 1550 nm, and this design can still achieve an ER over 27.26 dB and an IL less than 0.43 dB within a wavelength range of ± 50 nm, with an overall length of just 10 micrometers. The proposed structure offers high modulation efficiency and a low footprint, while also exhibiting high tolerance to fabrication errors, making it highly promising for future photonic communication systems.
{"title":"Compact hybrid waveguide optical switch with low loss and high extinction ratio based on Ge2Sb2Te5","authors":"Tong Jiang , Qipeng Zhan , Hao Ding , Zhixiang Huang , Li Ding","doi":"10.1016/j.photonics.2025.101368","DOIUrl":"10.1016/j.photonics.2025.101368","url":null,"abstract":"<div><div>High-efficiency and highly integrated optical switches in integrated photonic circuits have long been a pursuit for researchers. Due to the inherent limitations of silicon materials and fabrication processes, commonly used resonant or interferometric optical switches typically require tens to hundreds of micrometers of footprint to achieve desirable modulation efficiency. In response, we propose an optical switch structure filled with phase-change material (PCM) in a narrow slit, with tapered waveguides on curved sides coupling light in and out of the slit, enabling strong light-matter interaction. This structure consists of curved-side tapered coupling waveguides at both ends and a slit filled with GST (Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub>) in the middle. By applying an external stimulus to induce a phase change in the GST, which exhibits significant differences in optical properties between its crystalline and amorphous states, substantial modulation efficiency can be achieved. Operating in the transverse electric mode within the band of 1500–1600 nm, this structure can achieve an extinction ratio (ER) of 34.08 dB and an insertion loss (IL) of 0.18 dB at 1550 nm, and this design can still achieve an ER over 27.26 dB and an IL less than 0.43 dB within a wavelength range of ± 50 nm, with an overall length of just 10 micrometers. The proposed structure offers high modulation efficiency and a low footprint, while also exhibiting high tolerance to fabrication errors, making it highly promising for future photonic communication systems.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"64 ","pages":"Article 101368"},"PeriodicalIF":2.5,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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