Pub Date : 2025-11-24DOI: 10.1016/j.ijleo.2025.172612
Ghobad Mohammad Karimi , Mohammad Azim Karami , Hassan Ghalami Bavil Olyaee , Javad Karamdel
In this paper, The fundamental characteristic such as electronic and optical properties of silicon carbide nanosheets (3,3) are investigated using the density functional theory (DFT) by including defects and impurity dopings. In addition to the perfect layer analysis, four defect types are considered: one vacancy of silicon atom, one vacancy of carbon atom, two vacancies of atoms (a combined silicon and carbon vacancy) and Stone-Wales defect. Moreover, impurity doping effect for two perfect layers are studied, with each layer doped separately with a single nitrogen and molybdenum atom. The bandgap of the pristine layer was determined to be 2.82 eV, and simulation results indicate that the band gap significantly decreases by defect introduction, whereas the introduction of impurity doping results in only a slight reduction in the band gap. The layer with nitrogen doping exhibits the highest absorption coefficient, while the layer with a double carbon and silicon defect shows the lowest absorption coefficient.
{"title":"Electronic and optical properties of silicon carbide nanosheets (3,3) including defects and impurity dopings","authors":"Ghobad Mohammad Karimi , Mohammad Azim Karami , Hassan Ghalami Bavil Olyaee , Javad Karamdel","doi":"10.1016/j.ijleo.2025.172612","DOIUrl":"10.1016/j.ijleo.2025.172612","url":null,"abstract":"<div><div>In this paper, The fundamental characteristic such as electronic and optical properties of silicon carbide nanosheets (3,3) are investigated using the density functional theory (DFT) by including defects and impurity dopings. In addition to the perfect layer analysis, four defect types are considered: one vacancy of silicon atom, one vacancy of carbon atom, two vacancies of atoms (a combined silicon and carbon vacancy) and Stone-Wales defect. Moreover, impurity doping effect for two perfect layers are studied, with each layer doped separately with a single nitrogen and molybdenum atom. The bandgap of the pristine layer was determined to be 2.82 eV, and simulation results indicate that the band gap significantly decreases by defect introduction, whereas the introduction of impurity doping results in only a slight reduction in the band gap. The layer with nitrogen doping exhibits the highest absorption coefficient, while the layer with a double carbon and silicon defect shows the lowest absorption coefficient.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"345 ","pages":"Article 172612"},"PeriodicalIF":3.1,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616415","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 : 2025-11-24DOI: 10.1016/j.ijleo.2025.172620
O. Ben hammou , J. El-Hamouchi , A. Fakkahi , M. Jaouane , A. Ed – Dahmouny , H. Azmi , M. Jaafar , A. Mazouz , N. Zeiri , H. El Ghazi , A. Sali
This work presents a detailed investigation of the binding energy of a donor impurity positioned at the center of pyramidal core/shell/shell quantum dots, as well as the corresponding photoionization cross-section, under a Konwent-like confinement potential. The study examines the influence of confinement potential parameters and geometrical dimensions, as well as the combined effects of hydrostatic pressure and temperature. Within the effective mass approximation, the Schrödinger equation is numerically solved using the finite element method (FEM), ensuring high accuracy and computational efficiency. The results reveal that both the impurity binding energy and the photoionization cross-section are strongly influenced by the size of the nanostructure as well as the specific characteristics of the confinement potential. An increase in hydrostatic pressure leads to an enhancement of the donor binding energy, whereas higher temperatures induce a notable decrease. Additionally, the photoionization cross-section exhibits a pronounced peak when the photon energy matches the donor binding energy. Variations in system dimensions, confinement potential parameters, hydrostatic pressure, or temperature cause this resonance peak to shift either toward lower photon energies (red shift) or higher photon energies (blue shift).
{"title":"Donor binding energy and photoionization cross-section in pyramidal core/shell/shell quantum dots under external perturbations","authors":"O. Ben hammou , J. El-Hamouchi , A. Fakkahi , M. Jaouane , A. Ed – Dahmouny , H. Azmi , M. Jaafar , A. Mazouz , N. Zeiri , H. El Ghazi , A. Sali","doi":"10.1016/j.ijleo.2025.172620","DOIUrl":"10.1016/j.ijleo.2025.172620","url":null,"abstract":"<div><div>This work presents a detailed investigation of the binding energy of a donor impurity positioned at the center of pyramidal core/shell/shell quantum dots, as well as the corresponding photoionization cross-section, under a Konwent-like confinement potential. The study examines the influence of confinement potential parameters and geometrical dimensions, as well as the combined effects of hydrostatic pressure and temperature. Within the effective mass approximation, the Schrödinger equation is numerically solved using the finite element method (FEM), ensuring high accuracy and computational efficiency. The results reveal that both the impurity binding energy and the photoionization cross-section are strongly influenced by the size of the nanostructure as well as the specific characteristics of the confinement potential. An increase in hydrostatic pressure leads to an enhancement of the donor binding energy, whereas higher temperatures induce a notable decrease. Additionally, the photoionization cross-section exhibits a pronounced peak when the photon energy matches the donor binding energy. Variations in system dimensions, confinement potential parameters, hydrostatic pressure, or temperature cause this resonance peak to shift either toward lower photon energies (red shift) or higher photon energies (blue shift).</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"346 ","pages":"Article 172620"},"PeriodicalIF":3.1,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616969","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 : 2025-11-20DOI: 10.1016/j.ijleo.2025.172606
Mahdi Shayganmanesh, Mohammad Hossein Mahdieh, Reyhane Mokhtari
In this paper a microcylindrical resonator sensor was fabricated using PDMS polymer. The sensor works based on whispering gallery mode (WGM). The microcylinder filled with solution of Rhodamine 6B and glycerol. The Rhodamine was optically pumped by the second harmonics of a pulsed Nd:YAG laser beam and its emission provided WGM and resonance in microcylinder. The WGM spectra of microcylinder under applied forces were detected and analyzed by using a spectrophotometer. In addition to WGM spectra, optical images of the microcylinder under applied forces were taken using an appropriate optical set up and employing a CCD camera. The optical images show that any force on microcylinder side modifies its cross section from micro disk to micro elliptic. The experimental results show that such deformation in cross section leads to blue shift in WGM resonance wavelength. Using the geometrical data of images and a simple theory, the blue shifts due to force were estimated by calculations. The numerical results show good agreement with the experimental results.
{"title":"Numerical and experimental characterization of whispering gallery modes in a microcylinder for displacement and force sensing","authors":"Mahdi Shayganmanesh, Mohammad Hossein Mahdieh, Reyhane Mokhtari","doi":"10.1016/j.ijleo.2025.172606","DOIUrl":"10.1016/j.ijleo.2025.172606","url":null,"abstract":"<div><div>In this paper a microcylindrical resonator sensor was fabricated using PDMS polymer. The sensor works based on whispering gallery mode (WGM). The microcylinder filled with solution of Rhodamine 6B and glycerol. The Rhodamine was optically pumped by the second harmonics of a pulsed Nd:YAG laser beam and its emission provided WGM and resonance in microcylinder. The WGM spectra of microcylinder under applied forces were detected and analyzed by using a spectrophotometer. In addition to WGM spectra, optical images of the microcylinder under applied forces were taken using an appropriate optical set up and employing a CCD camera. The optical images show that any force on microcylinder side modifies its cross section from micro disk to micro elliptic. The experimental results show that such deformation in cross section leads to blue shift in WGM resonance wavelength. Using the geometrical data of images and a simple theory, the blue shifts due to force were estimated by calculations. The numerical results show good agreement with the experimental results.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"346 ","pages":"Article 172606"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145584388","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}
The increasing demand of biometric technology in various applications highlights the important role of iris image templates encryption in ensuring robust image security safeguarding the confidentiality, legitimacy, and authenticity of iris images. This paper presents a novel encryption technique designed to improve security of iris image templates. The proposed technique combines elliptic curve cryptography (ECC), chaotic umbrella maps, and an uneven modulus decomposition (UMD) algorithm. The Gyrator and fractional Fourier domains are jointly leveraged for their non-linear transformation characteristics, enhancing encryption complexity. The Umbrella Map is incorporated along with phase masks produced by elliptic curve cryptography to strengthen the security. To add an extra layer of security, pixel scrambling is also introduced, enabling the conversion of iris input images into a one-channel encrypted output. MATLAB simulations and security tests were carried out, including statistical analysis, critical sensitivity assessments, and a look at possible threats. The outcomes demonstrate the scheme's resistance to statistical inspection, important sensitivity analysis, and noise attacks. The robust encryption method ensures protection against known, specific, and plaintext assaults.
{"title":"Securing iris image templates through ECC-based phase retrieval mask and multi-domain transforms integrated with chaotic umbrella mapping","authors":"Bhavana Sharma , Pankaj Rakheja , Hukum Singh , Mehak Khurana","doi":"10.1016/j.ijleo.2025.172605","DOIUrl":"10.1016/j.ijleo.2025.172605","url":null,"abstract":"<div><div>The increasing demand of biometric technology in various applications highlights the important role of iris image templates encryption in ensuring robust image security safeguarding the confidentiality, legitimacy, and authenticity of iris images. This paper presents a novel encryption technique designed to improve security of iris image templates. The proposed technique combines elliptic curve cryptography (ECC), chaotic umbrella maps, and an uneven modulus decomposition (UMD) algorithm. The Gyrator and fractional Fourier domains are jointly leveraged for their non-linear transformation characteristics, enhancing encryption complexity. The Umbrella Map is incorporated along with phase masks produced by elliptic curve cryptography to strengthen the security. To add an extra layer of security, pixel scrambling is also introduced, enabling the conversion of iris input images into a one-channel encrypted output. MATLAB simulations and security tests were carried out, including statistical analysis, critical sensitivity assessments, and a look at possible threats. The outcomes demonstrate the scheme's resistance to statistical inspection, important sensitivity analysis, and noise attacks. The robust encryption method ensures protection against known, specific, and plaintext assaults.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"346 ","pages":"Article 172605"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145584481","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}
Laser interaction with matter is one of the fundamental fields of the thermophysics.
The problem of heating an isolated finite homogenous silver sulphide slab induced by a laser pulse is studied. Indeed pulsed laser are used in a variety of material processing applications.
The aim of the study is to evaluate quantitatively the thermal effects induced in the irradiated target. The output results will have essential importance in the field of technological applications.
In the present trial, the parabolic heat conduction equation is solved using Laplace integral transform technique which is one of the powerful methods in the field of mathematical physics. An express for the temperature field within the target is obtained.
The functional dependence of the temperature on the parameters of the laser pulse is clarified.
The computations makes it possible to evaluate the critical time required to initiate damage at the front surface, which is a starting point for medical, military, industrial applications.
An illustrative example on silver sulfide slab is given.
{"title":"Analytical modeling of heating effects induced in a finite silver sulfide (Ag2S) slab by a time dependent laser pulse using Laplace integral transform technique","authors":"M.K. El-Adawi, S.A. Shalaby, S.S. Mostafa, S.A. Antar","doi":"10.1016/j.ijleo.2025.172601","DOIUrl":"10.1016/j.ijleo.2025.172601","url":null,"abstract":"<div><div>Laser interaction with matter is one of the fundamental fields of the thermophysics.</div><div>The problem of heating an isolated finite homogenous silver sulphide <span><math><mrow><mfenced><mrow><mspace></mspace><mi>A</mi><msub><mrow><mi>g</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>S</mi></mrow></mfenced></mrow></math></span> slab induced by a laser pulse is studied. Indeed pulsed laser are used in a variety of material processing applications.</div><div>The aim of the study is to evaluate quantitatively the thermal effects induced in the irradiated target. The output results will have essential importance in the field of technological applications.</div><div>In the present trial, the parabolic heat conduction equation is solved using Laplace integral transform technique which is one of the powerful methods in the field of mathematical physics. An express for the temperature field within the target is obtained.</div><div>The functional dependence of the temperature on the parameters of the laser pulse is clarified.</div><div>The computations makes it possible to evaluate the critical time required to initiate damage at the front surface, which is a starting point for medical, military, industrial applications.</div><div>An illustrative example on silver sulfide slab is given.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"346 ","pages":"Article 172601"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145584383","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 : 2025-11-20DOI: 10.1016/j.ijleo.2025.172611
Wende Dong , Tianheng Xu , Muhan Ji , Gang Luo , Geng Li , Zhenzhen Zheng
In hazy weather, suspended particles in the air cause significant image degradation by attenuating and scattering light. This degradation poses substantial challenges to subsequent image processing tasks, such as target recognition and positioning. Existing methods often struggle to balance global atmospheric light estimation with fine-detail preservation, leading to residual haze or over-enhancement and color distortion. Inspired by attention mechanisms, we design a hazy image restoration architecture utilizing an improved U-Net based generative adversarial network (GAN), enhanced by a novel hybrid attention mechanism. This mechanism integrates a global attention modulator, a window-based multi-head self-attention module, and a locally enhanced feedforward network, enabling the model to effectively capture both global and local image features while mitigating the artifacts seen in prior work. The network is trained using a tailored loss function that combines pixel loss, adversarial loss, and edge loss, specifically designed for the image dehazing task. Extensive experiments conducted on synthetic and real hazy images demonstrate that the proposed method consistently delivers high-quality dehazed images with exceptional clarity and contrast, outperforming several state-of-the-art methods.
{"title":"Hybrid self-attention aided generative adversarial network for hazy image restoration","authors":"Wende Dong , Tianheng Xu , Muhan Ji , Gang Luo , Geng Li , Zhenzhen Zheng","doi":"10.1016/j.ijleo.2025.172611","DOIUrl":"10.1016/j.ijleo.2025.172611","url":null,"abstract":"<div><div>In hazy weather, suspended particles in the air cause significant image degradation by attenuating and scattering light. This degradation poses substantial challenges to subsequent image processing tasks, such as target recognition and positioning. Existing methods often struggle to balance global atmospheric light estimation with fine-detail preservation, leading to residual haze or over-enhancement and color distortion. Inspired by attention mechanisms, we design a hazy image restoration architecture utilizing an improved U-Net based generative adversarial network (GAN), enhanced by a novel hybrid attention mechanism. This mechanism integrates a global attention modulator, a window-based multi-head self-attention module, and a locally enhanced feedforward network, enabling the model to effectively capture both global and local image features while mitigating the artifacts seen in prior work. The network is trained using a tailored loss function that combines pixel loss, adversarial loss, and edge loss, specifically designed for the image dehazing task. Extensive experiments conducted on synthetic and real hazy images demonstrate that the proposed method consistently delivers high-quality dehazed images with exceptional clarity and contrast, outperforming several state-of-the-art methods.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"345 ","pages":"Article 172611"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570774","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 : 2025-11-20DOI: 10.1016/j.ijleo.2025.172609
Yongkang Yang , Baiang Qu , Hongjie Xu , Manqing Tan , Wentao Guo
The amplified spontaneous emission (ASE) source is widely used in fiber-optic gyroscopes due to its broadband spectrum, which suppresses backscattering- and Kerr-effect–induced phase errors while reducing polarization coupling noise. However, thermally induced wavelength drift remains a critical limitation in ultrahigh-precision systems, as even small spectral shifts introduce non-negligible phase noise. To address this challenge, we propose a wide-temperature wavelength-selective reflection strategy that integrates a wavelength-division multiplexer, optical filter, and reflector into a compact hybrid structure, achieving a mean drift rate below 0.1 ppm/°C across the full operational range. This work presents a significant advance in ASE source technology through the integration of dual fiber Bragg gratings (FBGs) at the 974 nm laser diode (LD) output and a monolithically packaged passive-component module. Comprehensive theoretical modeling and experimental characterization of LD–ASE spectral–power correlations enabled the development of a thermally optimized dual-pass architecture achieving three major performance breakthroughs: (1) ultra-stable wavelength performance with drift below 0.1 ppm/°C over –25°C to + 60°C, (2) ASE output power above 25 mW with < 5 % variation across the temperature cycle, and (3) a record-high optical conversion efficiency exceeding 20 %. These results establish new performance benchmarks for ASE sources used in ultrahigh-precision fiber-optic gyroscopes operating under extreme environmental conditions. The dual-FBG wavelength-stabilization method and hybrid integrated architecture effectively address long-standing challenges in maintaining spectral purity and power efficiency under thermal stress, marking a substantial advancement in photonic light-source technology for precision inertial navigation.
{"title":"High-power wavelength-stabilized amplified spontaneous emission source enabled by 974 nm LD and hybrid integration","authors":"Yongkang Yang , Baiang Qu , Hongjie Xu , Manqing Tan , Wentao Guo","doi":"10.1016/j.ijleo.2025.172609","DOIUrl":"10.1016/j.ijleo.2025.172609","url":null,"abstract":"<div><div>The amplified spontaneous emission (ASE) source is widely used in fiber-optic gyroscopes due to its broadband spectrum, which suppresses backscattering- and Kerr-effect–induced phase errors while reducing polarization coupling noise. However, thermally induced wavelength drift remains a critical limitation in ultrahigh-precision systems, as even small spectral shifts introduce non-negligible phase noise. To address this challenge, we propose a wide-temperature wavelength-selective reflection strategy that integrates a wavelength-division multiplexer, optical filter, and reflector into a compact hybrid structure, achieving a mean drift rate below 0.1 ppm/°C across the full operational range. This work presents a significant advance in ASE source technology through the integration of dual fiber Bragg gratings (FBGs) at the 974 nm laser diode (LD) output and a monolithically packaged passive-component module. Comprehensive theoretical modeling and experimental characterization of LD–ASE spectral–power correlations enabled the development of a thermally optimized dual-pass architecture achieving three major performance breakthroughs: (1) ultra-stable wavelength performance with drift below 0.1 ppm/°C over –25°C to + 60°C, (2) ASE output power above 25 mW with < 5 % variation across the temperature cycle, and (3) a record-high optical conversion efficiency exceeding 20 %. These results establish new performance benchmarks for ASE sources used in ultrahigh-precision fiber-optic gyroscopes operating under extreme environmental conditions. The dual-FBG wavelength-stabilization method and hybrid integrated architecture effectively address long-standing challenges in maintaining spectral purity and power efficiency under thermal stress, marking a substantial advancement in photonic light-source technology for precision inertial navigation.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"345 ","pages":"Article 172609"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570772","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 : 2025-11-20DOI: 10.1016/j.ijleo.2025.172607
J. Arriaga Hernández , B. Cuevas Otahola , A. Diaz Nayotl , A. Jaramillo Núñez , A. Pérez Villegas , O. Valenzuela
We apply new machine learning (ML) technologies to optimize the Hartmann test (HT) and Bi-Ronchi test (BRT) regarding the recognition, identification, and localization of the centroids in experimental Hartmanngrams and Bi-Ronchigrams. We replace the conventional rigid Hartmann screen (Hartmann mask, HM) with structured apertures implemented via a spatial light modulator (SLM), which enables the generation of multiple patterns with different aperture geometries. Based on the classical HM with circular apertures, we build square apertures for the Bi-Ronchi mask (BRM). We designed an experimental setup based on an SLM with a laser illumination system and implemented an unsupervised Centroid Clustering Algorithm (uCCA), based on the ML algorithm -means, to identify the geometries of the centroids, followed by their segmentation and localization by clustering. We compare the experimental and theoretical Bi-Ronchigrams (or Hartmanngrams) to obtain a point cloud of transverse aberrations (). We apply the point cloud method (PCM) to obtain an integrable surface from the points in . Finally, we replace the numerical integration of with transverse aberrations () and a directional derivative approach based on the Eikonal equation, solved using Gaussian quadrature to obtain the wavefront. We compare our results with the Zernike aberration polynomials for sensing optical elements from the aberrations of the system by means of the aberrations of its wavefront .
{"title":"Machine learning K-means algorithm applied to wavefront sensing in Bi-Ronchi/Hartmann tests with SLM","authors":"J. Arriaga Hernández , B. Cuevas Otahola , A. Diaz Nayotl , A. Jaramillo Núñez , A. Pérez Villegas , O. Valenzuela","doi":"10.1016/j.ijleo.2025.172607","DOIUrl":"10.1016/j.ijleo.2025.172607","url":null,"abstract":"<div><div>We apply new machine learning (ML) technologies to optimize the Hartmann test (HT) and Bi-Ronchi test (BRT) regarding the recognition, identification, and localization of the centroids in experimental Hartmanngrams and Bi-Ronchigrams. We replace the conventional rigid Hartmann screen (Hartmann mask, HM) with structured apertures implemented via a spatial light modulator (SLM), which enables the generation of multiple patterns with different aperture geometries. Based on the classical HM with circular apertures, we build square apertures for the Bi-Ronchi mask (BRM). We designed an experimental setup based on an SLM with a laser illumination system and implemented an unsupervised Centroid Clustering Algorithm (uCCA), based on the ML algorithm <span><math><mi>K</mi></math></span>-means, to identify the geometries of the centroids, followed by their segmentation and localization by clustering. We compare the experimental and theoretical Bi-Ronchigrams (or Hartmanngrams) to obtain a point cloud of transverse aberrations (<span><math><mi>P</mi><msub><mi>C</mi><mrow><mi>T</mi><mi>A</mi></mrow></msub></math></span>). We apply the point cloud method (PCM) to obtain an integrable surface from the points in <span><math><mi>P</mi><msub><mi>C</mi><mrow><mi>T</mi><mi>A</mi></mrow></msub></math></span>. Finally, we replace the numerical integration of <span><math><mrow><mi>P</mi><msub><mi>C</mi><mrow><mi>T</mi><mi>A</mi></mrow></msub></mrow></math></span> with transverse aberrations (<span><math><mi>T</mi><mi>A</mi></math></span>) and a directional derivative approach based on the Eikonal equation, solved using Gaussian quadrature to obtain the wavefront. We compare our results with the Zernike aberration polynomials for sensing optical elements from the aberrations of the system by means of the aberrations of its wavefront <span><math><mrow><mrow><mi>W</mi></mrow></mrow><mo>(</mo><mrow><mi>ρ</mi></mrow><mo>,</mo><mrow><mi>θ</mi></mrow><mo>)</mo></math></span>.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"346 ","pages":"Article 172607"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616970","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 : 2025-11-20DOI: 10.1016/j.ijleo.2025.172610
Iman Razmkhah, Zahra Adelpour, Mojtaba Sadeghi
In this work, we present a novel compact plasmonic dual-band bandpass filter based on graphene nanoribbons, tunable through azo-dye-doped liquid crystal and graphene conductivity. Graphene nanoribbons are deposited on a silica substrate and covered with azo-dye-doped liquid crystal. Therefore, the performance of the plasmonic structure can be tuned by a laser pump and the graphene chemical potential. Full-wave simulations are performed in COMSOL Multiphysics using the Finite Element Method (FEM). In addition, Transmission Line Modelling and Electromagnetic Scaling Law are used to validate the numerical simulation results. The proposed filter resonates at 2.45 THz and 9.2 THz when the laser pump is off. However, when the laser pump is on, the resonant frequencies redshift to 2.3 THz and 8.6 THz. The corresponding quality factors are 20 and 31 for the lower and higher resonance frequencies when the laser pump is off. The simulated reflection coefficients (S₁₁) reach −31 dB and −38 dB for the two passbands confirming efficient transmission (S₂₁≈ 0 dB). The effect of graphene chemical potential and geometric variations on our structure is investigated. Finally, the size and performance of our filter are compared with the previously reported designs, demonstrating both practical feasibility and compactness. With a compact footprint of 420 × 350 nm2 and dual-band tunability, the proposed filter is a promising candidate for terahertz sensing and communication systems.
{"title":"The design and TLM analysis of a compact graphene-based dual-band bandpass plasmonic filter with hybrid post-fabrication tunability via liquid crystal in the terahertz regime","authors":"Iman Razmkhah, Zahra Adelpour, Mojtaba Sadeghi","doi":"10.1016/j.ijleo.2025.172610","DOIUrl":"10.1016/j.ijleo.2025.172610","url":null,"abstract":"<div><div>In this work, we present a novel compact plasmonic dual-band bandpass filter based on graphene nanoribbons, tunable through azo-dye-doped liquid crystal and graphene conductivity. Graphene nanoribbons are deposited on a silica substrate and covered with azo-dye-doped liquid crystal. Therefore, the performance of the plasmonic structure can be tuned by a laser pump and the graphene chemical potential. Full-wave simulations are performed in COMSOL Multiphysics using the Finite Element Method (FEM). In addition, Transmission Line Modelling and Electromagnetic Scaling Law are used to validate the numerical simulation results. The proposed filter resonates at 2.45 THz and 9.2 THz when the laser pump is off. However, when the laser pump is on, the resonant frequencies redshift to 2.3 THz and 8.6 THz. The corresponding quality factors are 20 and 31 for the lower and higher resonance frequencies when the laser pump is off. The simulated reflection coefficients (S₁₁) reach −31 dB and −38 dB for the two passbands confirming efficient transmission (S₂₁≈ 0 dB). The effect of graphene chemical potential and geometric variations on our structure is investigated. Finally, the size and performance of our filter are compared with the previously reported designs, demonstrating both practical feasibility and compactness. With a compact footprint of 420 × 350 nm<sup>2</sup> and dual-band tunability, the proposed filter is a promising candidate for terahertz sensing and communication systems.</div></div>","PeriodicalId":19513,"journal":{"name":"Optik","volume":"345 ","pages":"Article 172610"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681839","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 : 2025-11-19DOI: 10.1016/j.ijleo.2025.172604
Sanjeev Mani Yadav
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