As a part of this investigation, we aim to develop a 1 × 2 multimode interferometer (MMI) beam splitter based on chalcogenide waveguides for dual RI profile simultaneous detection applications. The operating principle involves multiplexing transverse magnetic (TM) polarized light into two distinct channels, enabling the simultaneous detection of two RI profiles, which are considered as methane (CH₄) and nitrous oxide (N₂O) in this work. This approach is cost-effective, as the design integrates broadband near-infrared on-chip light emission with dispersive spectroscopic components, making it suitable for dual RI profile simultaneous detection. In this work, we focus on optimizing the width and length of the multimode interference region in the 1 × 2 MI, intending to enhance the imbalance between output ports and improve the contrast ratio. Additionally, the curvature of the S-bend waveguide is optimized to maximize output power while minimizing insertion loss. The spectral transmission characteristics of the MMI diplexer are analyzed with respect to variations in the refractive index (RI) of the sensing layer.
{"title":"Dual refractive index profile detection based on multimode interferometer","authors":"Lokendra Singh , Krishna Kant Agrawal , Prakash Pareek , Naveen Kumar Maurya , Vipul Agarwal","doi":"10.1016/j.photonics.2025.101475","DOIUrl":"10.1016/j.photonics.2025.101475","url":null,"abstract":"<div><div>As a part of this investigation, we aim to develop a 1 × 2 multimode interferometer (MMI) beam splitter based on chalcogenide waveguides for dual RI profile simultaneous detection applications. The operating principle involves multiplexing transverse magnetic (TM) polarized light into two distinct channels, enabling the simultaneous detection of two RI profiles, which are considered as methane (CH₄) and nitrous oxide (N₂O) in this work. This approach is cost-effective, as the design integrates broadband near-infrared on-chip light emission with dispersive spectroscopic components, making it suitable for dual RI profile simultaneous detection. In this work, we focus on optimizing the width and length of the multimode interference region in the 1 × 2 MI, intending to enhance the imbalance between output ports and improve the contrast ratio. Additionally, the curvature of the S-bend waveguide is optimized to maximize output power while minimizing insertion loss. The spectral transmission characteristics of the MMI diplexer are analyzed with respect to variations in the refractive index (RI) of the sensing layer.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"67 ","pages":"Article 101475"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623749","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 : 2025-12-01Epub Date: 2025-11-14DOI: 10.1016/j.photonics.2025.101476
Yulia Grigorovich , Sergey Geyman , Ildar Yusupov , Anton Kharchevskii , Irina Melchakova , Pavel Ginzburg , Mikhail Udrov
Accurate localization in relatively small volumes is essential for precisely tracking and managing wireless devices, allowing for detailed control and coordination in robotics, manufacturing, and healthcare applications, where even minor positional errors can significantly affect performance and safety. While high-frequency localization techniques may seem appealing, in many cases with heavy clutter, line-of-sight constraints significantly limit their performance, prompting the use of alternative low-frequency solutions. Here, we leverage the existing and well-established Near-Field Communication (NFC) architecture, widely deployed on consumer wireless devices, to demonstrate an exceptionally accurate localization technique that achieves millimeter-scale precision, even in perspective scenarios where massive objects obstruct the line of sight. The system uses a pair of large-area coils to establish a reliable NFC communication channel over distances of several meters. The position of a device, whether it is a tag or a smartphone equipped with a transceiver module, is determined by balancing the received signal strength, which is then mapped to a specific location in space. The NFC protocol, operating at 13.56 MHz with a corresponding free-space wavelength of 22 meters, exhibits minimal sensitivity to obstacles due to its reliance on near-field interactions rather than free-space propagation. In all demonstrations, millimeter-scale localization accuracy was achieved along a one-dimensional axis. NFC-based localization systems, to some extent serving as a compromise between extremely low-frequency and high-frequency implementations, can offer robust high-precision tracking solutions in environments where traditional methods encounter significant limitations.
{"title":"Long-range NFC device localization with millimeter-scale accuracy","authors":"Yulia Grigorovich , Sergey Geyman , Ildar Yusupov , Anton Kharchevskii , Irina Melchakova , Pavel Ginzburg , Mikhail Udrov","doi":"10.1016/j.photonics.2025.101476","DOIUrl":"10.1016/j.photonics.2025.101476","url":null,"abstract":"<div><div>Accurate localization in relatively small volumes is essential for precisely tracking and managing wireless devices, allowing for detailed control and coordination in robotics, manufacturing, and healthcare applications, where even minor positional errors can significantly affect performance and safety. While high-frequency localization techniques may seem appealing, in many cases with heavy clutter, line-of-sight constraints significantly limit their performance, prompting the use of alternative low-frequency solutions. Here, we leverage the existing and well-established Near-Field Communication (NFC) architecture, widely deployed on consumer wireless devices, to demonstrate an exceptionally accurate localization technique that achieves millimeter-scale precision, even in perspective scenarios where massive objects obstruct the line of sight. The system uses a pair of large-area coils to establish a reliable NFC communication channel over distances of several meters. The position of a device, whether it is a tag or a smartphone equipped with a transceiver module, is determined by balancing the received signal strength, which is then mapped to a specific location in space. The NFC protocol, operating at 13.56 MHz with a corresponding free-space wavelength of 22 meters, exhibits minimal sensitivity to obstacles due to its reliance on near-field interactions rather than free-space propagation. In all demonstrations, millimeter-scale localization accuracy was achieved along a one-dimensional axis. NFC-based localization systems, to some extent serving as a compromise between extremely low-frequency and high-frequency implementations, can offer robust high-precision tracking solutions in environments where traditional methods encounter significant limitations.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"67 ","pages":"Article 101476"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145579625","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 : 2025-09-01Epub Date: 2025-06-08DOI: 10.1016/j.photonics.2025.101410
Xiaoyun Wang , Sili Huang , Yan Chen , Shanjun Chen , Wei Dai , Jie Hou , Jingyu Wang , Weimin Yang , Shiyi Song
In this work, we propose a metamaterial perfect absorber based on the toroidal dipole mode. A nanopore is introduced in the center of GaP nanopixel, and a Si nanodisk is placed in it as the pattern layer. The dielectric layer comprising of SiO2 is on top of the substrate of Au. The finite difference time domain (FDTD) method was used to numerically simulate the metamaterial absorber, in which the absorption peak appeared at 1255.3 nm with a peak value of 99.6 % and a Q factor of 154.4. This study also demonstrated the high sensitivity of 339.6 nm/RIU to the environmental refractive index, surpassing previously reported designs and highlighting the potential applications of refractive index sensing. The proposed composite structure narrowband absorber based on Si and GaP has great application potential in perfect absorption, refractive index sensing and nonlinear photonics.
{"title":"Perfect absorber based on toroidal dipole in metamaterial of silicon and gallium phosphide","authors":"Xiaoyun Wang , Sili Huang , Yan Chen , Shanjun Chen , Wei Dai , Jie Hou , Jingyu Wang , Weimin Yang , Shiyi Song","doi":"10.1016/j.photonics.2025.101410","DOIUrl":"10.1016/j.photonics.2025.101410","url":null,"abstract":"<div><div>In this work, we propose a metamaterial perfect absorber based on the toroidal dipole mode. A nanopore is introduced in the center of GaP nanopixel, and a Si nanodisk is placed in it as the pattern layer. The dielectric layer comprising of SiO<sub>2</sub> is on top of the substrate of Au. The finite difference time domain (FDTD) method was used to numerically simulate the metamaterial absorber, in which the absorption peak appeared at 1255.3 nm with a peak value of 99.6 % and a Q factor of 154.4. This study also demonstrated the high sensitivity of 339.6 nm/RIU to the environmental refractive index, surpassing previously reported designs and highlighting the potential applications of refractive index sensing. The proposed composite structure narrowband absorber based on Si and GaP has great application potential in perfect absorption, refractive index sensing and nonlinear photonics.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101410"},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144291648","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}
THz wave can be modulated by electrical bias or by optical pumping. In the present work, we have fabricated graphene (Gr) based THz modulator on two Si/SiO2 substrates with different resistivities (10 kΩ.cm and 5 kΩ.cm) and studied the effect of their resistivities and doping on THz modulation by optical pumping. THz modulation by optical pumping was measured for 0.2 THz to 0.6 THz frequency range with varying pumping power from 0 mW to 800 mW using a 976 nm laser. The estimated modulation depth was ≈ 99 % at 800 mW in graphene on Si/SiO2 having lower resistivity (LRSi/SiO2) whereas it was < 2 % in graphene on Si/SiO2 having higher resistivity (HRSi/SiO2). The higher value of modulation depth in graphene on LRSi/SiO2 has been attributed to the lower resistivity of the substrate resulted in a larger number of free carriers for photoconduction in LRSi/SiO2 which contributed to the greater carrier concentration and THz conductivity. Raman spectroscopy further confirmed that the doping is greater in graphene on LRSi/SiO2 as compared to graphene on HRSi/SiO2. This resulted in an enhanced number of photocarriers responsible for higher THz modulation.
{"title":"Investigation of the effect of resistivity and defects on optical THz modulation of graphene on Si/SiO2 substrate","authors":"Abhilasha Chouksey , Shivnath Kumar , Preeti Gaur , Preeti Garg , Radhapiyari Laishram , Anupama Singh , J.S. Rawat , Neeraj Khare","doi":"10.1016/j.photonics.2025.101451","DOIUrl":"10.1016/j.photonics.2025.101451","url":null,"abstract":"<div><div>THz wave can be modulated by electrical bias or by optical pumping. In the present work, we have fabricated graphene (Gr) based THz modulator on two Si/SiO<sub>2</sub> substrates with different resistivities (10 kΩ.cm and 5 kΩ.cm) and studied the effect of their resistivities and doping on THz modulation by optical pumping. THz modulation by optical pumping was measured for 0.2 THz to 0.6 THz frequency range with varying pumping power from 0 mW to 800 mW using a 976 nm laser. The estimated modulation depth was ≈ 99 % at 800 mW in graphene on Si/SiO<sub>2</sub> having lower resistivity (LRSi/SiO<sub>2</sub>) whereas it was < 2 % in graphene on Si/SiO<sub>2</sub> having higher resistivity (HRSi/SiO<sub>2</sub>). The higher value of modulation depth in graphene on LRSi/SiO<sub>2</sub> has been attributed to the lower resistivity of the substrate resulted in a larger number of free carriers for photoconduction in LRSi/SiO<sub>2</sub> which contributed to the greater carrier concentration and THz conductivity. Raman spectroscopy further confirmed that the doping is greater in graphene on LRSi/SiO<sub>2</sub> as compared to graphene on HRSi/SiO<sub>2</sub>. This resulted in an enhanced number of photocarriers responsible for higher THz modulation.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101451"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324206","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 : 2025-09-01Epub Date: 2025-06-10DOI: 10.1016/j.photonics.2025.101419
K. Hasanirokh , E.B. AL , A.T. Tuzemen , M. Sayrac , H. Sayrac , F. Ungan
{"title":"Corrigendum to “Investigation of nonlinear optical properties in GaAs/GaAlAs quantum well with modified Lennard-Jones potential: Role of static electromagnetic fields, intense laser radiation and structure parameters” [Photonics Nanostruct. - Fundam. Appl. 65 (2025) 101403]","authors":"K. Hasanirokh , E.B. AL , A.T. Tuzemen , M. Sayrac , H. Sayrac , F. Ungan","doi":"10.1016/j.photonics.2025.101419","DOIUrl":"10.1016/j.photonics.2025.101419","url":null,"abstract":"","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101419"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988325","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 : 2025-09-01Epub Date: 2025-07-13DOI: 10.1016/j.photonics.2025.101428
Wenyuan Zhang , Xin Liu , Yuan Tian , Mingda Zhang , Binzhao Cao , Yibiao Yang , Hongming Fei , Fei Sun , Yichao Liu , Zhihui Chen
Metal-dielectric hybrid structures have become ideal platforms for enhancing fluorescence emission due to their ability to support strong resonances. This study presents a dual-resonance Tamm plasmon (TP) configuration integrating a one-dimensional photonic crystal (1DPC) with precisely optimized metallic gratings. By utilizing the synergistic COBYLA (Constrained Optimization BY Linear Approximations) algorithm, this design achieves comprehensive far-field enhancement of upconversion nanoparticles (UCNPs) fluorescence through synergistic excitation and emission manipulation. By exciting the optical Tamm mode within the structure, the hybrid structure successfully forms a strong localized electromagnetic field, benefiting excited-state absorption (ESA) with angle-insensitive excitation enhancement for both TE and TM polarizations. The far-field fluorescence emission enhancement was achieved for two different orientations of UCNPs. Notably, the maximum overall far-field enhancement factor reaches 1.04× 105-folds for x-orientation UCNPs, taking into account the effects of relaxation during the excitation process. Additionally, the results indicate that introducing the grating into the TP structure leads to an angular FWHM of 18.7°, which plays a crucial role in confining far-field radiation and enhancing fluorescence collection efficiency, thereby promoting highly directional emission. This TP-based platform demonstrates exceptional stability and multi-modal enhancement capability, holding substantial promise for advanced photonic applications including single-molecule biosensing, upconversion lighting, and other photon-based technologies that require high stability and substantial enhancement.
金属-介电杂化结构由于其支持强共振的能力而成为增强荧光发射的理想平台。本文提出了一种将一维光子晶体（1DPC）与精确优化的金属光栅集成在一起的双共振Tamm等离子体激元（TP）结构。本设计利用协同COBYLA （Constrained Optimization By Linear Approximations）算法，通过协同激发和发射操作，实现了上转换纳米粒子（UCNPs）荧光的全面远场增强。通过激发结构内部的光学Tamm模式，混合结构成功地形成了强大的局域电磁场，有利于TE和TM极化的激发态吸收（ESA）和角度不敏感的激发增强。两种不同取向的UCNPs均实现了远场荧光发射增强。值得注意的是，考虑到激发过程中的弛豫影响，x取向UCNPs的最大总远场增强因子达到1.04× 105倍。此外，结果表明，在TP结构中引入光栅后，其角频宽为18.7°，对限制远场辐射和提高荧光收集效率起着至关重要的作用，从而促进了高定向发射。这个基于tp的平台展示了卓越的稳定性和多模态增强能力，为先进的光子应用带来了巨大的希望，包括单分子生物传感、上转换照明和其他需要高稳定性和大量增强的光子技术。
{"title":"Simultaneous excitation and directional emission enhancements of upconversion fluorescence enabled by optical Tamm plasmon in hybrid structure with metal-photonic crystal and grating","authors":"Wenyuan Zhang , Xin Liu , Yuan Tian , Mingda Zhang , Binzhao Cao , Yibiao Yang , Hongming Fei , Fei Sun , Yichao Liu , Zhihui Chen","doi":"10.1016/j.photonics.2025.101428","DOIUrl":"10.1016/j.photonics.2025.101428","url":null,"abstract":"<div><div>Metal-dielectric hybrid structures have become ideal platforms for enhancing fluorescence emission due to their ability to support strong resonances. This study presents a dual-resonance Tamm plasmon (TP) configuration integrating a one-dimensional photonic crystal (1DPC) with precisely optimized metallic gratings. By utilizing the synergistic COBYLA (Constrained Optimization BY Linear Approximations) algorithm, this design achieves comprehensive far-field enhancement of upconversion nanoparticles (UCNPs) fluorescence through synergistic excitation and emission manipulation. By exciting the optical Tamm mode within the structure, the hybrid structure successfully forms a strong localized electromagnetic field, benefiting excited-state absorption (ESA) with angle-insensitive excitation enhancement for both TE and TM polarizations. The far-field fluorescence emission enhancement was achieved for two different orientations of UCNPs. Notably, the maximum overall far-field enhancement factor reaches 1.04× 10<sup>5</sup>-folds for <em>x</em>-orientation UCNPs, taking into account the effects of relaxation during the excitation process. Additionally, the results indicate that introducing the grating into the TP structure leads to an angular <em>FWHM</em> of 18.7°, which plays a crucial role in confining far-field radiation and enhancing fluorescence collection efficiency, thereby promoting highly directional emission. This TP-based platform demonstrates exceptional stability and multi-modal enhancement capability, holding substantial promise for advanced photonic applications including single-molecule biosensing, upconversion lighting, and other photon-based technologies that require high stability and substantial enhancement.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101428"},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144657214","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 : 2025-09-01Epub Date: 2025-06-12DOI: 10.1016/j.photonics.2025.101422
Zhenyuan Wang , Heyang Qin , Zheng-Da Hu , Wenyuan Wang , Tianhang Chen , Jingjing Wu , Jicheng Wang
We propose a double-layer metasurface to realize the polarization switching of fractional perfect composite vortex beams (FPCVBs). The metasurface is designed by the Jones matrix formalism and optimized through the “Random Forest” machine learning algorithm, achieving high polarization switching efficiency. The grafted-FPCVBs are presented with featuring multivariate topological charges, and double-ring FPCVBs are achieved with independent on/off modulation and shaping transformation of inner and outer ring intensities. These capabilities unlock orbital angular momentum density modulation and light field reconfiguration in composited light architectures. Moreover, we design an optical encryption protocol inspired by the hierarchical structure of chinese characters, where semantic radicals are mapped to polarization-encoded FPCVBs. These innovations present significant potential for applications in optical information security, particle manipulation, and next-generation photonic communications.
{"title":"Switchable fractional perfect composite vortex encryption based on double-layer metasurface","authors":"Zhenyuan Wang , Heyang Qin , Zheng-Da Hu , Wenyuan Wang , Tianhang Chen , Jingjing Wu , Jicheng Wang","doi":"10.1016/j.photonics.2025.101422","DOIUrl":"10.1016/j.photonics.2025.101422","url":null,"abstract":"<div><div>We propose a double-layer metasurface to realize the polarization switching of fractional perfect composite vortex beams (FPCVBs). The metasurface is designed by the Jones matrix formalism and optimized through the “Random Forest” machine learning algorithm, achieving high polarization switching efficiency. The grafted-FPCVBs are presented with featuring multivariate topological charges, and double-ring FPCVBs are achieved with independent on/off modulation and shaping transformation of inner and outer ring intensities. These capabilities unlock orbital angular momentum density modulation and light field reconfiguration in composited light architectures. Moreover, we design an optical encryption protocol inspired by the hierarchical structure of chinese characters, where semantic radicals are mapped to polarization-encoded FPCVBs. These innovations present significant potential for applications in optical information security, particle manipulation, and next-generation photonic communications.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101422"},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144314567","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 : 2025-09-01Epub Date: 2025-09-13DOI: 10.1016/j.photonics.2025.101446
Ferhat Hanife , Yosef Badali
In this study, the photoconductive properties of a Schottky photodiode with the structure Au/PVA:Graphite-Er₂O₃/n-Si are investigated both in the dark and under varying light intensities. A thin layer of the polyvinyl alcohol doped with Graphite-Er₂O₃ is placed at the metal-semiconductor interface to create an Schottky photodiode with a metal-nanocomposite-semiconductor structure. The fabrication and preparation techniques are thoroughly documented. X-ray diffraction (XRD) is used to analyze the Graphite and Er₂O₃ nanostructures. Several key photoconductive properties, such as leakage or reverse-saturation current (I₀), electric potential barrier height (ΦB0), and ideality factor (n), series/shunt resistances (Rs/Rsh), surface/interface state density distribution (Nss), photocurrent (Iph), photosensitivity (S), optical responsivity (R), and specific detectivity (D*) have been determined. Increasing light intensity leads to higher I₀ and n values, and lower ΦB0 and Rs values. When studying the illumination dependency of photocurrent, the Iph–P plots at zero bias voltage exhibit a linear behavior within an acceptable range. The PVA:Graphite-Er₂O₃ nanocomposite enhances the photosensitivity of the metal-nanocomposite-semiconductor type photodiode, optical responsivity, and specific detectivity by 1120, 2.40 mA/W, and 3.13 × 10 ¹ ⁰ Jones, respectively. These results suggest that the Au/PVA:Graphite-Er₂O₃/n-Si structure exhibits a promising photoresponse and could potentially replace traditional metal-semiconductor photodiode in optoelectronic devices and photovoltaic systems.
{"title":"Optical response of Au/n-Si schottky photodiode with an interface of graphite-Er2O3-doped polyvinyl alcohol (PVA) nanocomposite","authors":"Ferhat Hanife , Yosef Badali","doi":"10.1016/j.photonics.2025.101446","DOIUrl":"10.1016/j.photonics.2025.101446","url":null,"abstract":"<div><div>In this study, the photoconductive properties of a Schottky photodiode with the structure Au/PVA:Graphite-Er₂O₃/n-Si are investigated both in the dark and under varying light intensities. A thin layer of the polyvinyl alcohol doped with Graphite-Er₂O₃ is placed at the metal-semiconductor interface to create an Schottky photodiode with a metal-nanocomposite-semiconductor structure. The fabrication and preparation techniques are thoroughly documented. X-ray diffraction (XRD) is used to analyze the Graphite and Er₂O₃ nanostructures. Several key photoconductive properties, such as leakage or reverse-saturation current (<em>I₀</em>), electric potential barrier height (<em>Φ</em><sub><em>B0</em></sub>), and ideality factor (<em>n</em>), series/shunt resistances (<em>R</em><sub><em>s</em></sub><em>/R</em><sub><em>sh</em></sub>), surface/interface state density distribution (N<sub>ss</sub>), photocurrent (<em>I</em><sub><em>ph</em></sub>), photosensitivity (<em>S</em>), optical responsivity (<em>R</em>), and specific detectivity (<em>D*</em>) have been determined. Increasing light intensity leads to higher <em>I₀</em> and n values, and lower <em>Φ</em><sub><em>B0</em></sub> and <em>R</em><sub><em>s</em></sub> values. When studying the illumination dependency of photocurrent, the <em>I</em><sub><em>ph</em></sub>–<em>P</em> plots at zero bias voltage exhibit a linear behavior within an acceptable range. The PVA:Graphite-Er₂O₃ nanocomposite enhances the photosensitivity of the metal-nanocomposite-semiconductor type photodiode, optical responsivity, and specific detectivity by 1120, 2.40 mA/W, and 3.13 × 10 ¹ ⁰ Jones, respectively. These results suggest that the Au/PVA:Graphite-Er₂O₃/n-Si structure exhibits a promising photoresponse and could potentially replace traditional metal-semiconductor photodiode in optoelectronic devices and photovoltaic systems.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101446"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095204","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 : 2025-09-01Epub Date: 2025-10-10DOI: 10.1016/j.photonics.2025.101449
Amir Amir Mohammadi, Somayeh Makouei, Sajjad Mortazavi
Technological advancements have improved the quality of life but increased environmental pollution by releasing harmful gases such as ammonia, NOx, CO, H2S, and SO2. Accurate detection of toxic gases is crucial for human and ecosystem health, as it prevents severe health complications caused by inhaling these gases. This study introduces a PCF designed to detect harmful gases. The proposed fiber structure has a hybrid hole arrangement in the cladding. The two grid-like square inner layers are surrounded by three irregular octagonal outer layers. The core region consists of two ring layers enclosing a central air hole. Four intermediate air holes (I-Hole) are strategically positioned along the boundary between the core and cladding, which play a crucial role in fiber optical performance. The I-Holes act as reflective barriers, preventing light from escaping the core and redirecting it back into the core. The precise placement and function of these I-Holes contribute to the overall efficiency and performance of the fiber. Eventually, ultra-high relative sensitivity with ultra-low confinement loss is achieved. The proposed structure demonstrates a relative sensitivity of 88.06 ± 0.69 % and a confinement loss of 3.76 × 10−5 ± 9.95 × 10−5 dB/m with a 2.6 coefficient of variation within the 1.45μm to 1.7μm wavelength range.
{"title":"Ultra-high sensitivity and low loss: Innovative PCF simulated design featuring I-holes for harmful gas detection","authors":"Amir Amir Mohammadi, Somayeh Makouei, Sajjad Mortazavi","doi":"10.1016/j.photonics.2025.101449","DOIUrl":"10.1016/j.photonics.2025.101449","url":null,"abstract":"<div><div>Technological advancements have improved the quality of life but increased environmental pollution by releasing harmful gases such as ammonia, NO<sub>x</sub>, CO, H<sub>2</sub>S, and SO<sub>2</sub>. Accurate detection of toxic gases is crucial for human and ecosystem health, as it prevents severe health complications caused by inhaling these gases. This study introduces a PCF designed to detect harmful gases. The proposed fiber structure has a hybrid hole arrangement in the cladding. The two grid-like square inner layers are surrounded by three irregular octagonal outer layers. The core region consists of two ring layers enclosing a central air hole. Four intermediate air holes (I-Hole) are strategically positioned along the boundary between the core and cladding, which play a crucial role in fiber optical performance. The I-Holes act as reflective barriers, preventing light from escaping the core and redirecting it back into the core. The precise placement and function of these I-Holes contribute to the overall efficiency and performance of the fiber. Eventually, ultra-high relative sensitivity with ultra-low confinement loss is achieved. The proposed structure demonstrates a relative sensitivity of 88.06 ± 0.69 % and a confinement loss of 3.76 × 10<sup>−5</sup> ± 9.95 × 10<sup>−5</sup> dB/m with a 2.6 coefficient of variation within the 1.45μm to 1.7μm wavelength range.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101449"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324203","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 : 2025-09-01Epub Date: 2025-09-07DOI: 10.1016/j.photonics.2025.101445
Kai Lu , Long Chen , Chengyuan Li , Haojun Zhu , Chengchao Wang , Lanxin Ma
Colored passive cooling combines vibrant coloration with passive cooling capabilities, attracting significant interest in sustainable energy applications. While nanostructured colored passive cooling designs show promise, achieving precise colors with cooling power remains computationally challenging due to complex geometric parameter optimization. This study presents an innovative bidirectional design framework combining bidirectional neural network (BNN) and genetic algorithm (GA), to assist in the design of multilayer films. BNN accurately forecasts color and cooling power (99.67 % accuracy) from structural parameters and temperature T, and inversely designs geometric parameters (99.86 % accuracy) based on desired color and cooling performance at the given temperature. Crucially, the GA-based framework explores multiple high-precision solutions based on desired parameters, effectively addressing the “one-to-many” inverse design problem, overcoming the BNN’s single-solution limitation. The designed PMMA/TiN/TiO2/Ag films achieve a broad color gamut, covering 62 % of the CIE-1931 color space, while maintaining its equilibrium temperature only 2 −3 K above the ideal device. Together, these machine learning frameworks establish a full-cycle design paradigm: BNN enables bidirectional property-structure mapping with ultra-high accuracy while the GA- forward prediction model hybrid efficiently generates diverse optimal designs satisfying multi-objective constraints. This dual methodology accelerates the discovery of novel colored passive coolers, accelerating the development and deployment of energy-efficient solutions for significant contributions to energy conservation and sustainable development.
{"title":"Intelligent design of colored passive cooling multilayer films using bidirectional neural networks and genetic algorithms","authors":"Kai Lu , Long Chen , Chengyuan Li , Haojun Zhu , Chengchao Wang , Lanxin Ma","doi":"10.1016/j.photonics.2025.101445","DOIUrl":"10.1016/j.photonics.2025.101445","url":null,"abstract":"<div><div>Colored passive cooling combines vibrant coloration with passive cooling capabilities, attracting significant interest in sustainable energy applications. While nanostructured colored passive cooling designs show promise, achieving precise colors with cooling power remains computationally challenging due to complex geometric parameter optimization. This study presents an innovative bidirectional design framework combining bidirectional neural network (BNN) and genetic algorithm (GA), to assist in the design of multilayer films. BNN accurately forecasts color and cooling power (99.67 % accuracy) from structural parameters and temperature <em>T</em>, and inversely designs geometric parameters (99.86 % accuracy) based on desired color and cooling performance at the given temperature. Crucially, the GA-based framework explores multiple high-precision solutions based on desired parameters, effectively addressing the “one-to-many” inverse design problem, overcoming the BNN’s single-solution limitation. The designed PMMA/TiN/TiO<sub>2</sub>/Ag films achieve a broad color gamut, covering 62 % of the CIE-1931 color space, while maintaining its equilibrium temperature only 2 −3 K above the ideal device. Together, these machine learning frameworks establish a full-cycle design paradigm: BNN enables bidirectional property-structure mapping with ultra-high accuracy while the GA- forward prediction model hybrid efficiently generates diverse optimal designs satisfying multi-objective constraints. This dual methodology accelerates the discovery of novel colored passive coolers, accelerating the development and deployment of energy-efficient solutions for significant contributions to energy conservation and sustainable development.</div></div>","PeriodicalId":49699,"journal":{"name":"Photonics and Nanostructures-Fundamentals and Applications","volume":"66 ","pages":"Article 101445"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046092","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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