Abdolrasoul Gharaati; Ghasem Forozani; Sara Khosravani
Abstract
This paper investigates the structure of Josephson junctions, which, as one of the most fundamental elements in superconductivity, play a key role in the advancement of condensed matter physics, quantum field theory, and modern quantum technologies. The governing equation for the phase of such a system ...
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This paper investigates the structure of Josephson junctions, which, as one of the most fundamental elements in superconductivity, play a key role in the advancement of condensed matter physics, quantum field theory, and modern quantum technologies. The governing equation for the phase of such a system in the absence of dissipation and dispersion is the ordinary sine-Gordon equation, which describes fluxon propagation without considering the effects of dissipation and dispersion. However, in real physical system, the constituent materials of Josephson junctions always accompanied by dissipation and dispersion, which can significantly affect the dynamical behavior of fluxons. Here, by generalizing the sine-Gordon equation and including terms corresponding to dissipation and dispersion, and also considering the normalized bias current as a control parameter, the dynamics of fluxons in Josephson junctions have been studied. The result of this study show that the effects of dissipation and dispersion, especially in the presence of a normalized bias current, play a decisive role in the stability, propagation velocity of fluxons. The findings of this research confirm that considering dissipation and dispersion coefficients is essential and cannot be neglected in most cases. According to the calculations and simulations performed, it is observed that the effect of loss and dispersion can be compensated with the help of bias current. Therfore, the studies presented in this paper can be considered an effective step towards more realistic simulation of fluxon dynamics in parctical superconducting system.
Ali Kazempour
Abstract
In the context of strong field-matter interaction, an increasing number of phenomena have emerged that can be well understood when taking into account the vibrational modes of lattice i.e., phonons. Phonons dynamics as a result of coupling between electronic and lattice degree of freedom has substantial ...
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In the context of strong field-matter interaction, an increasing number of phenomena have emerged that can be well understood when taking into account the vibrational modes of lattice i.e., phonons. Phonons dynamics as a result of coupling between electronic and lattice degree of freedom has substantial effect on transient features via redistribution of quasiparticle populations and dynamical modification of coupling strength. In this study, we resolve the role of nonlinear phononics in nonlinear optics phenomena such as second harmonic generation and shift current including phonons for series of 2D materials. Our results show strong dynamical modulation of the electron-phonon effect in the dynamical Born effective charge for all individual phonon modes. The presence of activated phonons also enhances the second-order terms of second harmonic generation and shift current. The parameter amplification of light by nonlinear phonons enhance the control over phonon-polariton waves, interesting for information transport on subwavelength length scales.
Hadi Rahimi; Ahmad Heshmati
Abstract
This study investigates the optical density in a one-dimensional photonic crystal structure composed of alternating layers of silica and zirconia deposited on a polycarbonate substrate. The analysis employs the transfer matrix method to evaluate transmission spectra of both transverse electric and transverse ...
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This study investigates the optical density in a one-dimensional photonic crystal structure composed of alternating layers of silica and zirconia deposited on a polycarbonate substrate. The analysis employs the transfer matrix method to evaluate transmission spectra of both transverse electric and transverse magnetic polarizations. Within the 400-1600 nm spectral range, the structure exhibits a photonic bandgap spanning 750-1200 nm. The results show that the edges of this band gap are shifted towards shorter wavelengths in both transverse electric and transverse magnetic polarizations with increasing angle of incidence. Also, we observed distinct polarization-dependent behavior: optical density gradually increases with angle for TE polarization while decreasing for TM polarization. The lower the transmittance corresponds the higher the optical density, and vice versa. These findings can be used in spectroscopic analysis, optical sensing technologies, advanced optical window design, and radiation shielding applications, etc.
Azadeh Ahmadian
Abstract
This paper investigates the effects of helical and planar wiggler fields on electron acceleration in an inverse free-electron laser (IFEL) with a circularly polarized laser beam, in the presence of an increasing external magnetic field. The influence of wiggler parameters, the slope of the external magnetic ...
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This paper investigates the effects of helical and planar wiggler fields on electron acceleration in an inverse free-electron laser (IFEL) with a circularly polarized laser beam, in the presence of an increasing external magnetic field. The influence of wiggler parameters, the slope of the external magnetic field, and the laser intensity parameter on the dynamics and acceleration of electrons have been examined. Numerical results show that in both helical and planar wiggler configurations, a significant amount of energy transferred to the electron when optimal parameters selected for the laser, wiggler field, and external magnetic field. In the helical wiggler case, the electron energy gain reaches up to 2.42 GeV, while in the planar wiggler case, the maximum energy gain is about 1.85 GeV. This comparative analysis provides a deeper understanding of electron dynamics in inverse free-electron lasers and highlights the advantages of using a helical wiggler over a planar one.
Ameneh Kargarian; Soolmaz Jamali
Abstract
Nowadays, due to the importance of energy consumption in industrial applications of plasma generation systems, the electrical characterization of their parameters is very important. In this paper, the power consumption of a surface dielectric barrier discharge plasma system with a grid structure, utilizing ...
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Nowadays, due to the importance of energy consumption in industrial applications of plasma generation systems, the electrical characterization of their parameters is very important. In this paper, the power consumption of a surface dielectric barrier discharge plasma system with a grid structure, utilizing two different dielectric materials, quartz and alumina, was measured and compared at various applied voltages. The main objective is to investigate the effect of the dielectric material on the power consumption of the grid surface plasma system under different voltage conditions. To measure the discharge current and calculate power consumption, a Rogowski coil-based current measurement method was employed. This method allows for precise recording of the fast and transient currents present during the plasma discharge process. The results indicate that the type of dielectric material has a significant impact on the system’s power consumption. Specifically, alumina, due to its distinct electrical and thermal properties, leads to lower power consumption compared to quartz. The findings of this study can be useful for the optimal selection of dielectric materials in the design of high-efficiency plasma systems for various industrial, medical, and environmental applications.
Hamed Alizadeh; Mohammad Mofarreh
Abstract
This paper proposes a novel design of a visible light communication (VLC) system enhanced by an optical intelligent reflecting surface (OIRS) to support large-scale indoor applications. The system leverages the programmable reflectivity of the optical IRS to optimize light propagation, thereby improving ...
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This paper proposes a novel design of a visible light communication (VLC) system enhanced by an optical intelligent reflecting surface (OIRS) to support large-scale indoor applications. The system leverages the programmable reflectivity of the optical IRS to optimize light propagation, thereby improving signal coverage and quality across expansive indoor environments. A detailed system model is formulated, incorporating the characteristics of VLC channels and the controllable properties of the optical IRS. Through mathematical analysis and extensive simulations, we demonstrate that the proposed system significantly enhances the signal-to-noise ratio (SNR) and extends coverage compared to conventional VLC systems. The findings validate the efficacy of the optical IRS-based VLC system as a robust solution for high-speed, reliable wireless communication in large indoor spaces such as warehouses, shopping malls, and conference centers.
Robabeh Talebzadeh; Shabnam Andalibi Miandoab
Abstract
we considered a layered structure based on one dimensional photonic crystals consisting of alternating layers of silica and air, as well as a cavity is coated by superconducting nanocomposites based on Bismuth. Using the transfer matrix method, we investigated the transmittance spectrum of the structure. ...
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we considered a layered structure based on one dimensional photonic crystals consisting of alternating layers of silica and air, as well as a cavity is coated by superconducting nanocomposites based on Bismuth. Using the transfer matrix method, we investigated the transmittance spectrum of the structure. We showed that in the transmittance spectrum of the proposed structure, clear resonant modes can be found for each of the different brain tissue samples, whose positions depend on the structure parameters, for example, the filling factor. Therefore, the study of the proposed structure as a biosensor for brain diseases can be useful in the design of sensing devices. By optimizing the parameters and using Bismuth-based high-temperature superconducting materials (BSCCO), we increased the sensitivity of the proposed structure, for example, for a type of brain disease called Lymphoma to .
nosratali vahabzadeh
Abstract
In this study, we systematically investigate the structural, electronic, optical, and thermoelectric properties of the two-dimensional (2D) material MoSi₂N₄ using density functional theory (DFT)-based calculations. Energy–volume analysis confirms the thermodynamic stability of MoSi₂N₄, ...
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In this study, we systematically investigate the structural, electronic, optical, and thermoelectric properties of the two-dimensional (2D) material MoSi₂N₄ using density functional theory (DFT)-based calculations. Energy–volume analysis confirms the thermodynamic stability of MoSi₂N₄, as evidenced by its high bulk modulus, mechanical hardness, and low compressibility. Electronic band structure and density of states (DOS/PDOS) analyses reveal a direct band gap of approximately 2 eV, suggesting its strong potential for optoelectronic applications. Phonon spectrum analysis further validates the material’s dynamical stability and indicates favorable phonon characteristics for thermal conductivity and electron–phonon coupling. Optical calculations demonstrate pronounced anisotropy in the dielectric function, absorption spectra, and plasmonic response across the visible and ultraviolet regions. Additionally, the computed thermoelectric parameters, including the Seebeck coefficient and figure of merit (ZT), highlight the promise of MoSi₂N₄ for thermoelectric energy conversion technologies. Overall, these findings identify MoSi₂N₄ as a multifunctional 2D material with significant potential for applications in nanoelectronics, optoelectronics, and energy-related devices.