Optik最新文献

{"title":"Enhanced empirical relations for higher-order dispersions modeling in holey fibers","authors":"Ashkan Ghanbari","doi":"10.1016/j.ijleo.2025.172504","DOIUrl":"10.1016/j.ijleo.2025.172504","url":null,"abstract":"<div><div>In this paper, a set of enhanced empirical relations is introduced to enhance the design process of silica-based photonic crystal fibers (PCFs). These relations, which apply to the U parameter and higher-order dispersions, depend solely on the air hole diameter and wavelength. The accuracy of these relations is rigorously validated by comparing them with results obtained from the finite-difference time-domain (FDTD) method. This approach offers a computationally efficient alternative to conventional methods, eliminating the need for extensive numerical simulations, time-consuming design processes, and complex coding. As a result, it enables a simplified and rapid evaluation of the fundamental properties and dispersion characteristics of PCFs, making it a powerful tool for dispersion engineering in various nonlinear applications. Moreover, the method not only improves computational efficiency but also accelerates the design and optimization processes, offering significant advantages over traditional simulation-based approaches.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172504"},"PeriodicalIF":3.1,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903064","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}

{"title":"Band gap engineering and optoelectronic properties of europium-doped cesium tin chloride (Eu-doped CsSnCl3) perovskite using a DFT based first-principles GGA+U+SOC approach for PC-LED applications","authors":"Salman Ahmad ,&nbsp;Amin Ur Rahman ,&nbsp;Sikander Azam ,&nbsp;Muhammad Asif Hasham ,&nbsp;Asiya Zaman Khan","doi":"10.1016/j.ijleo.2025.172506","DOIUrl":"10.1016/j.ijleo.2025.172506","url":null,"abstract":"<div><div>This research investigates the potential of europium-doped cesium tin chloride perovskite (Eu-doped CsSnCl₃) as phosphor material for LED applications. We conducted computational analysis using first-principles calculations, specifically implementing the GGA+<em>U</em>+SOC methodology through WIEN2k software, to evaluate how europium (Eu) substitutional doping affects the material's electronic and optical behavior. The study compared pure CsSnCl₃ with two europium doping concentrations: a single-atom case Eu-CsSnCl₃ (2.5 %) and a double-atom scenario of 2Eu-CsSnCl₃ (5 %). Our findings demonstrate that Eu incorporation significantly alters the electronic band structure, with the band gap decreasing from 3.2 eV in pristine CsSnCl₃ to 1.009 eV and 0.967 eV for the 2.5 % and 5 % europium concentrations, respectively. This modification occurs through the formation of additional electronic states within both the valence and conduction bands. The research revealed that the 2.5 % europium concentration yielded optimal optical characteristics, particularly within visible light wavelengths, exhibiting improved absorption coefficients and more pronounced optical features compared to both the pristine material and the 5 % Eu variant. Through examination of dielectric properties, optical conductivity, and energy loss patterns, we determined that europium incorporation creates optimal conditions for light absorption and emission processes. These results indicate that precisely controlled Eu doping of CsSnCl₃ represents a viable approach for developing advanced phosphor materials with adjustable color properties and enhanced performance for future LED applications.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172506"},"PeriodicalIF":3.1,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893213","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}

{"title":"Metal layer integration in one-dimensional photonic crystal for enhanced malaria biosensor sensitivity","authors":"T. Shibina ,&nbsp;T. Sreejith ,&nbsp;B. Nithyaja ,&nbsp;K.S. Pramod","doi":"10.1016/j.ijleo.2025.172508","DOIUrl":"10.1016/j.ijleo.2025.172508","url":null,"abstract":"<div><div>Photonic crystal-based biosensors are attracting growing interest due to their high sensitivity and ultrafast response in biomedical diagnostics. We present a theoretical analysis and performance comparison of two one-dimensional photonic crystal (1D-PhC) structures aimed at malaria detection. The variation in the refractive index of the defect layer corresponding to various stages of malaria causes a shift in the transmission peak of the defect mode. The Transfer Matrix Method (TMM) is used to compute the transmission spectra. A Finite Element Method (FEM) tool COMSOL Multiphysics is used for studying the electric field distribution in the PhC structure. The integration of the metal layer on either side of the defect layer improved sensing performance. To investigate the tunable characteristics, variations were made in the type of metal, metal layer width, defect layer refractive index and incident angle for TE and TM polarisations. The presence of surface plasmon waves at the metal-dielectric interface enhances the sensitivity to small changes in the refractive index, enabling more effective detection. The novelty of the work includes the development of a PhC-based biosensor for malaria detection with sufficient sensitivity and transmission intensity using a small volume of sample defect. Sensor with silver layer achieved a sensitivity of 265.2 nm/RIU, a quality factor of 1.35 × 10², a resolution of 3.771 × 10⁻⁴ RIU, a figure of merit (FOM) of 49 RIU⁻¹ and response time of 18 fs with transmission 63 %. The proposed structure has a total thickness of 3.12 μm and offers a compact, cost-effective design with ultrafast response.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172508"},"PeriodicalIF":3.1,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144885692","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}

{"title":"Recent advances in graphene-based terahertz microstrip antennas: A technical review of substrate choices and emerging challenges","authors":"Abdelaaziz El Ansari ,&nbsp;Shobhit K. Khandare ,&nbsp;Najiba El Amrani El Idrissi","doi":"10.1016/j.ijleo.2025.172507","DOIUrl":"10.1016/j.ijleo.2025.172507","url":null,"abstract":"<div><div>The Terahertz (THz) spectrum, bridging the microwave and infrared regions, holds immense promise for high-speed communications, imaging, and sensing. However, efficient THz antenna design remains a critical challenge due to issues like narrow bandwidth and signal attenuation. This review focuses on recent advances in graphene based microstrip antennas for THz applications, with a particular emphasis on substrate selection and associated design challenges. Graphene’s exceptional electrical conductivity, high electron mobility, and tunable surface impedance make it an ideal candidate for reconfigurable and miniaturized THz antennas. The study categorizes and compares both linearly and circularly polarized THz antenna designs, highlighting the impact of conductive and substrate materials on impedance, bandwidth, gain, and polarization characteristics. Polyimide and SiO₂ emerge as leading substrate materials due to their low loss, thermal stability, and compatibility with graphene. Circularly polarized antennas demonstrate promising axial ratio bandwidths and gains when employing graphene polyimide and graphene-SiO₂ combinations. Despite notable advancements, challenges such as limited gain-bandwidth tradeoffs, polarization purity, and fabrication complexity remain. The review concludes by identifying future research directions, including substrate engineering, reconfigurable architectures, and dual polarization techniques, to meet the growing demands of next-generation THz communication systems.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172507"},"PeriodicalIF":3.1,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866498","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}

{"title":"Design of large relative aperture off-axis reflective system based on vector aberration theory","authors":"Yang Chao ,&nbsp;Chen Xu ,&nbsp;Baohua Wang ,&nbsp;Guoliang Li ,&nbsp;Zhiyang Qi","doi":"10.1016/j.ijleo.2025.172500","DOIUrl":"10.1016/j.ijleo.2025.172500","url":null,"abstract":"<div><div>The off-axis reflective optical system exhibits characteristics such as the absence of chromatic aberration, a wide operational spectral range, suitability for large apertures, and a compact structure. These features significantly advance the development of space remote sensing technology. As application requirements continue to evolve, there is an increasing demand for space remote sensors to acquire optical remote sensing data that encompasses broader ranges and contains more detailed information. This trend imposes higher demands on technical parameters including imaging field of view, relative aperture, imaging quality, and energy integration of optical payloads. To address these challenges, this paper presents the design of an improved COOK off-axis five-mirror system. This was achieved through structural selection and direct design based on vector aberration theory applied to the initial structure of an unobscured off-axis reflective system. Following adjustments and optimization processes, the modulation transfer function of the designed optical system exceeds [email protected] lp/mm, while energy integration within a <span><math><mrow><mn>48</mn><mspace></mspace><mi>μ</mi><mtext>m</mtext><mo>×</mo><mn>48</mn><mspace></mspace><mi>μ</mi><mtext>m</mtext></mrow></math></span> area surpasses 0.94. The imaging quality of the optical system is significantly improved, which meets the requirements of the system’s technical indicators. The designed system can achieve a large field of view, high energy utilization and low stray light simultaneously, which can greatly improve the design efficiency of the space optical system.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172500"},"PeriodicalIF":3.1,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893212","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}

{"title":"Enhanced THz emission from unmagnetized plasma using quadratically chirped HChG laser pulse","authors":"Jyoti Rajput,&nbsp;Renu Rajput","doi":"10.1016/j.ijleo.2025.172503","DOIUrl":"10.1016/j.ijleo.2025.172503","url":null,"abstract":"<div><div>Terahertz (THz) radiation generation through laser-plasma interactions has emerged as a promising approach for producing high-intensity, broadband THz sources. In this study, we investigate the enhancement of THz emission by employing a quadratically chirped Hermite-Cosh-Gaussian laser beam interacting with an underdense plasma. The purpose of this study is to investigate the enhancement of THz emission by employing a quadratically chirped Hermite-Cosh-Gaussian laser beam interacting with an underdense plasma. Tailoring the chirp profile significantly amplifies asymmetric electron motion and transient nonlinear currents, resulting in the generation of stronger and more tunable THz radiation. The results reveal that there is a significant relation between the THz field profile and laser parameters like the chirp parameter <span><math><mi>b</mi></math></span>, decentred parameter <span><math><mi>d</mi></math></span>, and mode index <span><math><mi>m</mi></math></span> of the Hermite function. Numerical analysis demonstrates that quadratic chirping optimizes the phase matching between the driving beam and the plasma response, resulting in an increased THz yield and a broader spectral bandwidth compared to conventional linear chirping. Our results reveal that the application of quadratic chirp improves temporal phase matching, enhances nonlinear electron motion, and leads to a notable increase in THz field amplitude. We observe that higher-order spatial modes and optimal decentering further amplify the THz yield, and the maximum enhancement is achieved at lower chirp values compared to linear chirping. There is a significant enhancement of THz amplitude at a lower value of the chirp parameter, i.e. <span><math><mrow><mi>b</mi><mo>=</mo><mn>0.0099</mn></mrow></math></span>.These findings underscore the efficacy of chirp engineering as a strategic tool for designing next-generation THz sources based on laser–plasma platforms. The proposed framework holds significant promise for applications in broadband spectroscopy, secure wireless communication, medical diagnostics, and ultrafast material characterization.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172503"},"PeriodicalIF":3.1,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144858297","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}

{"title":"Challenges in the design & development of efficient (High Power) lighting systems","authors":"Sananda Raychaudhuri,&nbsp;Tejaswi Challa,&nbsp;Jiji V","doi":"10.1016/j.ijleo.2025.172495","DOIUrl":"10.1016/j.ijleo.2025.172495","url":null,"abstract":"<div><div>21st century witnessed tremendous progress in the application of Photonics, one of the prominent being lighting industry. The automotive lighting, among various categories of lighting, received immense growth. The lamps which have once been mere candles or lanterns now comprise of several components strategically packed into various sizes, shapes tailored to add unique aesthetics to the vehicle. The current day lamps are not only complex in the structural aspect but also in the end functionality making (night) driving experience dynamic, smart, and safe. For several years such intelligent systems were mere R&amp;D, marketing ideas but the recent changes in legal regulations made Adaptive Front Lighting (AFS) systems, Adaptive Driving Beams (ADB) , Grill Lighting etc. (including the recent approval for ADB Headlamps in the US) conventional on the latest vehicles around the world. These rapid transitions, together with the continuous advancements in electronics sector, manufacturing technologies, and automotive qualified materials make the new generation lighting system designs more challenging, competent. Advanced lighting technologies are extremely complex and sensitive. For e.g., the adaptive beams AFS, ADB demands dynamically controlled light distributions from a single optical system , along with a quick response time. In this article, we attempt to provide an overview of some of the current day challenges the lighting designers are encountered with. We present the challenges associated with the development of ‘Efficient High Power Lighting System’. The state-of-the-art market demands of such systems, some of the key limitations of the current design solutions are outlined in this article.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172495"},"PeriodicalIF":3.1,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144840733","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}

{"title":"Behavior of an optical vortex immediately behind a spherical lens illuminated by circularly polarized light","authors":"V.V. Kotlyar ,&nbsp;A.A. Kovalev ,&nbsp;S.S. Stafeev ,&nbsp;A.M. Telegin","doi":"10.1016/j.ijleo.2025.172505","DOIUrl":"10.1016/j.ijleo.2025.172505","url":null,"abstract":"<div><div>In this paper we show that when focusing light with right circular polarization, an optical vortex with a topological charge equals to two is formed immediately behind a spherical lens for two transverse projections of the electric field and an optical vortex with a topological charge of unity for the longitudinal projection of the electric vector. This is proven by the fact that when illuminating a lens with an optical vortex with a topological charge of – 2 and right-hand circularly polarization, a ring-shaped intensity distribution is formed at the focus and a local intensity maximum occurs on the optical axis. This intensity maximum on the optical axis is the result of mutual compensation of the optical vortex with a topological charge of – 2 incident on the lens with the optical vortex with a topological charge of 2 formed after the spherical lens. Optical vortices with charges 2 and – 2 formed at the focus of light with linear polarization are responsible for the elliptical shape of the focal spot elongated along the direction of linear polarization.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172505"},"PeriodicalIF":3.1,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829183","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}

{"title":"Segmentation of plant leaf images in natural scenes by integrating graph diffusion compactness and global refinement","authors":"Lyasmine Adada ,&nbsp;Idir Filali ,&nbsp;Bouzefrane Samia","doi":"10.1016/j.ijleo.2025.172493","DOIUrl":"10.1016/j.ijleo.2025.172493","url":null,"abstract":"<div><div>Plant recognition, driven by advancement in image processing and machine learning, is crucial for ecological studies and agricultural management. However, challenges arise in complex backgrounds, requiring robust algorithms to differentiate target plants from surrounding elements. Leaf image segmentation is pivotal in accurately isolating and analyzing individual leaf structure, facilitating precise species identification. In this paper, we propose an algorithm for leaf segmentation in complex backgrounds. Our approach is notable for its low computational complexity making it well-suited for environments with restricted computational resources. First, we delimit roughly leaf areas in order to define the foreground template. Second, we rank the similarity of remaining image regions according to the foreground template through a graph based saliency process. Finally, the obtained contrast map is refined by using random forests to ensure optimal leaf/background separation. Experiments demonstrate that our algorithm outperforms several competing segmentation methods.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172493"},"PeriodicalIF":3.1,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829235","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}

{"title":"Modeling nonlinear optical polarization microscopy for visualizing magnetic domain walls","authors":"Mikhail A. Stepanov,&nbsp;Sergey D. Lavrov","doi":"10.1016/j.ijleo.2025.172497","DOIUrl":"10.1016/j.ijleo.2025.172497","url":null,"abstract":"<div><div>In this work, we present numerical modeling of nonlinear second harmonic generation polarization microscopy for visualization and differentiation of Bloch- and Néel-type magnetic domain walls. The developed model accounts for the spatial distribution of pump and second harmonic fields in various polarization configurations. Our results demonstrate the capability not only to detect the presence of domain boundaries but also to distinguish their types based on characteristic features in the SHG intensity distribution. It was observed that at certain pump polarization angles, the contrast between magnetic domains vanishes, enabling selective visualization of domain walls exclusively. A qualitative difference in SHG response between Bloch- and Néel-type domain walls was identified. The presented approach offers promising prospects for the investigation of more complex magnetic structures using nonlinear optical microscopy methods.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"338 ","pages":"Article 172497"},"PeriodicalIF":3.1,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739336","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}