- 标题
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Magnetic-field Induced SPP Near-field Modulation in Magnotoplasmonic Heterostructures with Ultralong-range Propagating Modes
摘要： In this paper, a solution to the double curl equation with generalized Coulomb gauge is proposed based on the vectorial representation of the magnetic vector potential. Traditional Coulomb gauge is applied to remove the null space of the curl operator and hence the uniqueness of the solution is guaranteed. However, as the divergence operator cannot act on edge elements (curl-conforming) directly, the magnetic vector potential is represented by nodal elements, which is too restrictive, since both the tangential continuity and the normal continuity are required. Inspired by the mapping of Whitney forms by mathematical operators and Hodge (star) operators, the divergence of the magnetic vector potential, as a whole, can be approximated by Whitney elements. Hence, the magnetic vector potential can be expanded by the edge elements, where its vectorial nature is retained and only the tangential continuity is required. Finally, the original equation can be rewritten in a generalized form and solved in a more natural and accurate way using finite-element method.
关键词： Whitney forms,generalized Coulomb gauge,Finite-element method (FEM),magnetostatic
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Fabrication of Ultrasmall Silicon Waveguide Lenses Designed by Wavefront-Matching Method
摘要： We design and fabricate ultrasmall silicon waveguide lenses designed by a wavefront-matching (WFM) method by a standard CMOS process. It is experimentally demonstrated that a low-loss several micron free-space light propagation is possible by using the waveguide lens designed by the WFM method.
关键词： Finite-element method,Optimum design method,Silicon waveguide device
更新于2025-09-16 10:30:52
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Discoveries and Explorations of Mode Splitting Phenomenon in Lossy Dielectric Waveguide
摘要： We discovered that a specific transmission mode in the fiber waveguide will split into two modes at near cut-off conditions when the fiber is coated with lossy dielectric nanofilms with higher refractive index. One of the two splitting modes is high lossy while the other is slightly lossy. We defined the “mode splitting coefficient” to describe the degree of mode splitting. We found that the biggest mode splitting coefficient was obtained at the mode cut-off wavelength using finite element method. Finally, we put forward an explanation towards the mode splitting phenomenon and expounded the relationship between the mode splitting and mode coupling.
关键词： Mode coupling,Mode splitting phenomenon,Finite element method,Lossy dielectric waveguide
更新于2025-09-16 10:30:52
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[IEEE 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Barcelona, Spain (2019.9.2-2019.9.6)] 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Propagation of Laser-Driven Electromagnetic Pulses in Laser Target Areas
摘要： During high intense laser target interaction a strong electromagnetic pulse (EMP) is generated which can potentially disturb the well performing of the experiment. The electromagnetic interference (EMI) due to the EMP not only affects devices present in the vacuum chamber but also in the target area where it may compromise the performance or operation of electronics and device controllers. In this work we report the measurements of EMP inside the laser target area at Centro de Laseres Pulsados (CLPU) during high intense laser-target interaction experiments. The experimental results show how the amplitude and spectrum of the EMP in the target area is different from the one inside the target chamber (TC). At last Finite element method (FEM) simulation results are shown and compared with experimental results.
关键词： laser-plasma interaction,Electromagnetic interference (EMI),High Intense laser,Electromagnetic Pulse (EMP),Finite Element Method (FEM) simulations
更新于2025-09-16 10:30:52
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Laser Resonance Frequency Analysis: A Novel Measurement Approach to Evaluate Acetabular Cup Stability During Surgery
摘要： Artificial joint acetabular cup stability is essential for successful total hip arthroplasty. However, a quantitative evaluation approach for clinical use is lacking. We developed a resonance frequency analysis (RFA) system involving a laser system that is fully contactless. This study aimed to investigate the usefulness of laser RFA for evaluating acetabular cup stability. First, the finite element method was performed to determine the vibration mode for analysis. Second, the acetabular cup was press-fitted into a reamed polyurethane cavity that replicated the human acetabular roof. The implanted acetabular cup was vibrated with pulse laser irradiation and the induced vibration was detected with a laser Doppler vibrometer. The time domain signal from the vibrometer was analyzed by fast Fourier transform to obtain the vibration frequency spectrum. After laser RFA, the pull-down force of the acetabular cup was measured as conventional implant fixation strength. The frequency of the first highest amplitude between 2 kHz and 6 kHz was considered as the resonance peak frequency, and its relationship with the pull-down force was assessed. The peak frequency could predict the pull-down force (R2 = 0.859, p < 0.000). Our findings suggest that laser RFA might be useful to measure acetabular cup stability during surgery.
关键词： implant stability,laser,resonance frequency analysis,total hip arthroplasty,finite element method,acetabular cup
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Structured Auxiliary Mesh (SAM) Algorithm for Opto-Thermal Simulation of Laser-Based Lighting Systems
摘要： Laser-based lighting systems are an emerging technology, the next step in solid state lighting that revolutionized the way artificial light is generated. The configuration of interest here is the laser-excited remote phosphor (LRP) scheme that consists of a laser diode as the excitation source of an appropriately chosen phosphor sheet. The phosphor is employed for the down-conversion of the incident laser light and broadening of the output spectrum. Although some commercial applications have already been developed, the optimization of LRP systems has yet to be achieved. A bottleneck in their performance is the thermal dependency of the phosphor’s emission characteristics, a phenomenon also known as thermal quenching. As a result, the need for an opto-thermal simulation strategy arises that will enable the study and optimization of LRP systems [1]. The opto-thermal simulation model discussed here is based on Monte Carlo simulations for the optical part, where the absorbed radiant flux is calculated. These optical thermal losses are subsequently used as a volume heat source to solve the transient heat equation by applying the finite element method (FEM) [2]. As thermal quenching is a time-dependent phenomenon in nature, this is an iterative procedure, where the absorbed flux must be calculated for most of the time steps. Typical Monte Carlo ray tracing algorithms use voxel-based meshes to store any calculated properties / attributes. The problem that arises here is that the computational cost for converting the voxel-based mesh to an FEM mesh would be prohibiting for time-dependent analysis. The solution is to directly store the absorbed flux to the FEM mesh. However, the issue that now emerges is locating the interpolating point, namely the point in space where the absorption occurs, within the unstructured FEM mesh. The processing time of a brute force search would be too long, so more sophisticated solutions must be found. SAM algorithms, which were first introduced in [3], are part of a class of algorithms known as geometric search algorithms [4, 5] that deal with point location in unstructured meshes. We propose here a modified SAM algorithm that uses the optical voxel-based mesh as the auxiliary structured mesh for geometric searching. The two meshes, optical and FEM, are superimposed. As point location in voxel-based meshes is trivial, by mapping which elements of the FEM mesh belong to each voxel, we can easily narrow down the number of searches required. To this end, two maps, implemented as binary search trees, are implemented. The first map, maps the voxel number to the nodes of the FEM mesh that lie within it, while the second map, maps the elements of the unstructured mesh that these nodes belong to. The set-up times of these maps heavily depend on the density of the FEM mesh and the order of the elements used. The use of higher-order elements results in considerable set-up times. As higher order elements are not necessary for thermal analysis, this is not a critical issue here. On the other hand, the denser the optical mesh, the fewer FEM elements are mapped to each voxel. However, the size of voxels should be appropriately chosen, since too small voxels may lead to degenerative cases where there are voxels without any nodes lying in them. A distinct advantage of this method is that once the maps are assembled, the search time of elements is O(1). Simulation plays an increasingly crucial role in the study and optimization of optical systems. Due to the increase in computational capabilities, modelling of more complex phenomena can be included and the need of multi-physics approaches rises. The optical properties of materials often shift to temperature above tolerance levels that may render a particular optical design ineffective. In other cases, structural loads may be the critical issue as they can lead to misalignment of optical elements. The proposed SAM algorithm that enables a more efficient coupling of optical and FEM analysis is a valuable tool to such approaches of optical problems.
关键词： Laser-based lighting systems,opto-thermal simulation,Monte Carlo simulations,SAM algorithm,finite element method,thermal quenching
更新于2025-09-16 10:30:52
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Analysis of the Heat Affected Zone and Surface Roughness during Laser Micromachining of Metals
摘要： The current research focuses on the characterization of the produced heat affected zone when laser heats AISI H13 steel, AISI 1045 steel and Ti6Al4V alloy workpieces via finite element simulations and experimental investigation. The surface roughness designedly varies on the surface of the samples and its influence on the absorption of laser light is investigated. Experiments are conducted at 1-4 W laser power and for two scanning speeds of 2 and 100 mm/min. A 3D transient thermo-structural finite element model for a moving Gaussian laser heat source is developed to simulate the micromachining process and predict the depth and width of the heat affected zone. The Johnson-Cook material model that takes into account the effect of plastic strain, strain rate and temperature, along with a fracture model, is adapted to the simulations. A good agreement between the experimental data and the simulation results is found. The depth and width of the heat affected zone strongly depend on the laser parameters and material properties of the irradiated samples. This study constitutes the basis to the optimization and improvement of the laser assisted micromachining process parameters and provides key insights on the roughness-absorptivity relation for the three metallic materials.
关键词： finite element method,heat affecting zone,white-light interferometry,laser heating
更新于2025-09-16 10:30:52
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Numerical Modeling of Plasma Silicon Discharge for Photovoltaic Application
摘要： In this work, we perform a numerical modeling of silicon thin film deposition for a photovoltaic application in a capacitive coupled plasma reactor (CCP) using RF excitation. Plasma equations are solved by finite element numerical method. The deposition is done by plasma of SiH4/Ar/H2 in low pressure and low temperature. The results provide the fundamental features of plasma discharge such as density, temperature and electrical potential. It is shown that the gas mixture used covers a large energy range, which entails a high deposition rate. Furthermore, the use of CCP reactor yields a uniform deposition without surface deterioration.
关键词： Numerical modeling,RF Plasma,CCP reactor,SiH4/Ar/H2,Finite Element Method
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Comparison of magnetic field imaging (MFI) and magnetic field simulation of silicon solar cells
摘要： In solar cells, electric currents are generated by electric injection or light flow distributed over the whole area. Each flowing current generates a magnetic field depending on the strength and the direction of the electric current. Recently, a new measuring technology, called magnetic field imaging (MFI) was presented showing the potential to measure the electric current strength and direction by imaging the resulting magnetic fields. The method was applied to various defects, e.g. missing or defect solder point between solar cell interconnector and cross-connector. Here, MFI measurements of various solar cell configurations and solar cell defects are compared with a finite elemental magnetic field simulation. The results are qualitatively and quantitatively interpreted and discussed. The model is used to obtain limits in resolution depending on measuring height and measurable defects (connector brakeage or defect soldering point) of the MFI method. The variation of geometry and material parameters (within reasonable boundaries) on the current flow and the corresponding magnetic field distribution show negligible influence of manufacturing tolerances regarding layer thicknesses and ribbon/connector width as well as material fluctuations resulting in variation of electrical resistance. Measuring height and electrical current have the biggest influence on magnetic field strength and are therefore starting points for process and product optimization.
关键词： magnetic field imaging,FEM,finite element method,MFI,solar cell defects,silicon solar cells
更新于2025-09-16 10:30:52
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Evaluation of Nanoplasmonic Optical Fiber Sensors Based on D-Type and Suspended Core Fibers with Metallic Nanowires
摘要： The introduction of metallic nanostructures in optical fibers has revolutionized the field of plasmonic sensors since they produce sharper and fine-tuned resonances resulting in higher sensitivities and resolutions. This article evaluates the performance of three different plasmonic optical fiber sensors based on D-type and suspended core fibers with metallic nanowires. It addresses how their different materials, geometry of the components, and their relative position can influence the coupling between the localized plasmonic modes and the guided optical mode. It also evaluates how that affects the spatial distributions of optical power of the different modes and consequently their overlap and coupling, which ultimately impacts the sensor performance. In this work, we use numerical simulations based on finite element methods to validate the importance of tailoring the features of the guided optical mode to promote an enhanced coupling with the localized modes. The results in terms of sensitivity and resolution demonstrate the advantages of using suspended core fibers with metallic nanowires.
关键词： suspended core fiber,metallic nanowires,finite-element method,optical fiber sensors,D-type fiber,surface plasmon resonance,plasmonic refractive index sensor
更新于2025-09-16 10:30:52