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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) - Electromagnetic Diffraction by Fractal Dusts, Triangles and Carpets: A Kirchhoff Approach to Circulation
摘要： The diffraction of plane waves by perfectly-conducting thin screens is of fundamental physical and mathematical interest in electromagnetics [1]. Classic laser-optics experiments involve both open (single- and double-slit arrangements) and closed (circular and regular-polygon) apertures, with analyses often being confined to the Fresnel [2] and Fraunhofer [3] regimes. Here, we consider a class of scattering problem involving fully-2D fractal screens, where the scatterer possesses the property of self-similarity. A more general formulation of the diffracted wave, based on Kirchhoff’s theory and 3D Green’s functions [4], is also deployed.
关键词： Kirchhoff’s theory,self-similarity,diffraction,Green’s functions,fractal screens
更新于2025-09-16 10:30:52
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Design of miniaturized high selectivity folded substrate integrated waveguide band pass filter with Koch fractal
摘要： This paper proposes the design of a novel double folded substrate integrated waveguide (FSIW) band pass filter (BPF) based on Koch space-filling curve (SFC). The folded SIW filter is incorporated with first and second iteration levels of Koch curve on central conducting layer. A prototype of second iteration Koch fractal FSIW BPF has been fabricated using substrate having dielectric constant 2.55 and thickness 0.508 mm for each layer and then tested. The fabricated second order filter has merits of compact size (0.204 λ0 2), high roll off rate (82.2 dB/GHz) and low insertion loss (<0.85 dB) in the X band.
关键词： Folded Substrate Integrated Waveguide (FSIW) Koch fractal,selectivity,Bandpass filter,miniaturization
更新于2025-09-16 10:30:52
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Self-organized fractal-like structures formation on the silicon wafer surface using the femtosecond laser pulses
摘要： In this paper interaction of a di?erent number of femtosecond laser pulses and various ?uences with silicon wafer has been studied. E?ects of the pulse number and the laser ?uence on self-organized structures created during femtosecond laser pulses processing are investigated. The scanning electron microscopy images of the sample show that by increasing the number of laser pulses, spike-like structures form on the surface, which gradually transform to hills and holes structure. The increment of the laser ?uence causes the microstructures to grow in diameter. However, the increase in diameter is limited by surface stability. When the micro-structures are at their maximum size and a stable geometrical shape, further ?uence increment can cause new self-organized nanos-tructures to be created over the microstructures’ surface. The hierarchical micro and nanostructures created after femtosecond laser pulse interaction have a similar shape. Thus fractal-like structures formed in the femtosecond pulse laser processing can be useful in the surface nano-structuring applications.
关键词： Femtosecond,Silicon,Spikes,Ripples,Fractal,Laser
更新于2025-09-16 10:30:52
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Lorenz Type Behaviors in the Dynamics of Laser Produced Plasma
摘要： An innovative theoretical model is developed on the backbone of a classical Lorenz system. A mathematical representation of a differential Lorenz system is transposed into a fractal space and reduced to an integral form. In such a conjecture, the Lorenz variables will operate simultaneously on two manifolds, generating two transformation groups, one corresponding to the space coordinates transformation and another one to the scale resolution transformation. Since these groups are isomorphs various types isometries become functional. The Lorenz system was further adapted to describe the dynamics of ejected particles as a result of laser matter interaction in a fractal paradigm. The simulations were focused on the dynamics of charged particles, and showcase the presence of current oscillations, a heterogenous velocity distribution and multi-structuring at different interaction scales. The theoretical predictions were compared with the experimental data acquired with noninvasive diagnostic techniques. The experimental data confirm the multi-structure scenario and the oscillatory behavior predicted by the mathematical model.
关键词： plasma structuring,fractal analysis,laser produced plasmas,ionic oscillations,Lorenz system
更新于2025-09-16 10:30:52
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Effect of fractal parameters on optical properties of cold rolled aluminum alloy strips with induced surface deflection: simulations and experimental correlations
摘要： Cold rollings for Al5182 aluminum alloy strips are carried out to evaluate the optical parameters with the applications of two lubricants and various operating conditions. In order to obtain these optical parameters, the fractal parameters which includes periodic lengths (????, ????) and fractal dimensions (????, ????) in the modified three-dimensional formula for the fractal surface between two predominant asperities and increase minimum illuminance and decrease maximum provide an effective way to correlate these fractal parameters with the optical parameters using TracePro software, which can help to define rolling conditions efficiently for the specific demand morphology have been solved first for the rolled surfaces. This three-dimensional formula can minimum illuminance. While an increment in ???? and ???? would increase the characteristic distance of optical properties. The deterministic results for fractal surface simulations using MATLAB in series and 20o incident angle simulation in TracePro software explain that an increase in ???? and ???? will yield dense profiles which elevates the maximum illuminance and lower down the illuminance. Finite element analyses prove that different friction coefficients in the upper and lower rolls potentially induce surface deflection and thus affect the optical properties. A high illuminance uniformity can be achieved by making a compromise among the fractal parameters (????, ????, ???? and ????) such that a small difference in the maximum and minimum illuminances is available.
关键词： Induced deflection angle after rolling,3D formula for fractal surface morphology,Optical properties in reflection,Fractal dimensions and periodic lengths of rolled surface
更新于2025-09-12 10:27:22
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Plasmon-polariton fractal spectra in quasiperiodic photonic crystals with graphene
摘要： In this work we study the plasmon-polariton spectra in one-dimensional photonic crystals based on the Fibonacci, Thue-Morse and double-period sequences, where we have graphene at the interface of one of the constituent building blocks (A = SiO2/graphene, B = SiO2). The dispersion relations for each quasicrystal are numerically calculated by using a transfer-matrix approach. The spectra of these structures are shown to be fractals (for the bulk bands distribution), obeying a power law in a particular frequency region and these are induced specifically by the quasiperiodic ordering in the unit cells of each system studied. We also report a strong dependence of the width of the bulk bands on the wave vector for this particular frequency region, whereas for large wave vectors the fractal properties in these spectra are absent.
关键词： transfer-matrix approach,plasmon-polariton,quasiperiodic photonic crystals,fractal spectra,graphene
更新于2025-09-12 10:27:22
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Particle distribution in transient plasmas generated by ns-laser ablation on ternary metallic alloys
摘要： Understanding the fundamental mechanisms behind industrial laser-based technologies represents one the cornerstones of the development and tailoring of new materials. With the thin-film deposition using laser ablation being one of the most important techniques for obtaining complex materials with controllable stoichiometry, there is a high request for both experimental and theoretical studies towards understanding the behavior of multi-component alloys under high-power laser irradiation. Here we investigate the laser ablation process on two ternary metallic alloys (Cu–Mn–Al and Fe–Mn–Si) by means of space-and time-resolved optical emission spectroscopy and fast camera imaging with the focus being on the spatial distribution of each composing element. Information regarding the kinetic and thermal energy of the ejected particles is extracted and discussed in the framework of an inner structuring of the laser-produced plasmas based on a mass and energy distribution. The hypothesis is then verified by implementing a fractal analysis to the multi-component plasmas. The theoretical fractal approach offers results in good agreement with the experimental data gives important insight in the inner dynamics of complex laser-produced plasmas.
关键词： Ternary metallic alloys,Optical emission spectroscopy,Fractal analysis,Fast camera imaging,Laser ablation
更新于2025-09-12 10:27:22
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Reconstruction of surface errors of the metallic waveguide based on electromagnetic scattering theory
摘要： First, the fractal model of surface errors was constructed by means of the Monte Carlo method, and the source term and spectral amplitude of surface errors were calculated. The reconstruction model of surface errors was then established. The non-differentiable problem of the fractal model was solved by the fractional differential theory. To verify the accuracy of proposed models, a waveguide filter was manufactured. The reconstruction results obtained by the fractal function model were compared with the measured results, and a comparison of the results obtained by different reconstruction models proves that the fractal function is optimal in modelling.
关键词： metallic waveguide,electromagnetic scattering,fractal function,reconstruction,surface error
更新于2025-09-12 10:27:22
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A quad‐band Sierpenski based fractal antenna fed by co‐planar waveguide
摘要： In this article, A Sierpenski based octagonal carpet fractal antenna is introduced for quad-band applications. The proposed antenna developed with FR-4 substrate material with relative permittivity of 4.4, thickness chosen is 1.6 mm and co-planar waveguide feed is used in this design. The antenna is designed, simulated with computer simulation technology studio suite, printed and tested. The measurement results of proposed antenna resonates at 2.4, 4.45, 9.1, 10.24, 12.46 GHz and are well suited for C-band(2.4 GHz), L-band (4.45 GHz), X-band (9.1 GHz, 10.24 GHz), Ku-band (12.46 GHz) applications. Good agreement between the results of simulation and measurement is observed with applications.
关键词： Sierpenski fractal antenna,multiband applications,quad-band,co-planar waveguide
更新于2025-09-11 14:15:04
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Pulsed electropolymerization of PEDOT enabling controlled branching
摘要： Controlling the growth of conductive polymers via electrolysis enables defined surface modifications and can be used as a rapid prototyping process. In this study, the controlled dendritic growth of poly(3,4-ethylenedioxythiophene) in a two-electrode setup was investigated by pulsed voltage-driven electropolymerization of the precursor EDOT and a low concentration of tetrabutylammonium perchlorate dissolved in acetonitrile. Rapid growth of different polymeric shapes was reliably achieved by varying the reduction voltage and duty factor. The obtained structures were optically examined and quantified using fractal dimensions. Their shapes ranged from solid coatings over branched fractals to straight fibers without requiring any template. These rapid and controllable electropolymerization processes were further combined to increase conductor complexity.
关键词： fractal dimensions,dendritic growth,electropolymerization,PEDOT,pulsed voltage
更新于2025-09-11 14:15:04