Mehrasa Ayatollahi; Maryam Rouzbehi
Abstract
A B S T R A C TIn this research, we investigate the stability of harmonic oscillator systems. To achieve this, we transform the differential equation describing the oscillator into a state-space model using appropriate variables, enabling the application of matrix algebraic relationships to design a ...
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A B S T R A C TIn this research, we investigate the stability of harmonic oscillator systems. To achieve this, we transform the differential equation describing the oscillator into a state-space model using appropriate variables, enabling the application of matrix algebraic relationships to design a stabilizing controller for the system under study. Within the state-space framework, by utilizing state matrices and eigenvalue assignment techniques, we can develop a state feedback control law. The parameters of this controller are tuned such that the closed-loop system eigenvalues (which determine stability) are positioned in favorable locations within the complex plane, thereby ensuring system stability.
Ashkan Sadeghi; Mohammad Soroosh; Haraprasad Mondal
Abstract
In this research, a sensor based on surface plasmon resonance with a BK7/ZnO/Ag/ZnO/WSe2 structure is proposed for detecting the dengue virus based on blood hemoglobins, operating at a wavelength of 633 nm. A BK7 prism is used to couple light into the structure. The layer arrangement of the structure ...
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In this research, a sensor based on surface plasmon resonance with a BK7/ZnO/Ag/ZnO/WSe2 structure is proposed for detecting the dengue virus based on blood hemoglobins, operating at a wavelength of 633 nm. A BK7 prism is used to couple light into the structure. The layer arrangement of the structure consists of a silver film as the main plasmonic material, two ZnO layers that enclose the silver film; the first to compensate for the weak bonding between the silver and the prism, and the second to protect the silver against oxidation and corrosion as well as to improve sensitivity, and one layer of two-dimensional WSe2 material to enhance sensitivity and increase biomolecular interaction. The structure was designed and simulated using COMSOL software. The obtained values for the sensor parameters are sensitivity of 49.287 °/RIU, full width at half maximum of 2.669°, detection accuracy of 0.3747 deg-1, quality factor of 107.72 RIU-1, and signal-to-noise ratio of 3.77. The effects of the thickness of the Ag and ZnO layers and the number of WSe2 layers on the sensor’s performance were also investigated.
Hojjat Amrollahi Bioki
Abstract
Considering the environmental challenges arising from lead toxicity and the poor stability of conventional perovskite solar cells, the development of eco-friendly perovskite alternatives has become a major research priority. In this study, simultaneously investigate the effects of precursor solution ...
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Considering the environmental challenges arising from lead toxicity and the poor stability of conventional perovskite solar cells, the development of eco-friendly perovskite alternatives has become a major research priority. In this study, simultaneously investigate the effects of precursor solution concentration and post-deposition annealing temperature on the structural, morphological, and optical properties of spin-coated tin(II) iodide (SnI2) thin films, used as a precursor for lead-free perovskite solar cells. Scanning electron microscopy (SEM) analysis revealed that a precursor concentration of 375 mg/ml SnI2 in precursor solution and annealing at 100 °C provided optimal conditions for producing uniform films with densely packed grains (80–120 nm), controlled porosity, and a significant reduction in surface defects. In contrast, raising the annealing temperature to 150 °C induces thermal degradation and the formation of undesirable anisotropic oxide phases, ultimately reducing both optical and electronic performance. UV–vis spectroscopy confirmed strong absorption edge near 650 nm and the best optical performance was observed for films annealed at 100 °C. Tauc plot analysis determined a direct bandgap of 1.87 eV under optimal conditions accompanied by a reduced Urbach energy of 105 meV, indicating fewer defect states and improved crystallinity. Photoluminescence (PL) spectra further suggested enhanced charge transport and suppressed nonradiative recombination for optimized annealed films. These improvements in morphology and optoelectronic quality make SnI2 thin films annealed at 100 °C as a promising candidate for high-efficiency, lead-free perovskite solar cells, offering a viable strategy to enhance both performance and stability in developing photovoltaic technology.
Firouz Langarizadeh; Mohammad Javad Faghihi; Hamid Reza Baghshahi
Abstract
In this paper, based on the Jaynes-Cummings model, the Hamiltonian of a system consisting of two nonidentical two-level atoms and a quantized electromagnetic field is introduced, in the presence of dipole-dipole interaction and Kerr-like medium. In order to arrive at the wave function of the system, ...
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In this paper, based on the Jaynes-Cummings model, the Hamiltonian of a system consisting of two nonidentical two-level atoms and a quantized electromagnetic field is introduced, in the presence of dipole-dipole interaction and Kerr-like medium. In order to arrive at the wave function of the system, the Schrödinger equation in the interaction picture is analytically obtained in a specific situation: one of the atoms in a resonance and the other in a non-resonance. Then, the atomic population inversion, entanglement between two atoms, and entanglement between two atoms and the field are numerically investigated. The results indicate that dipole-dipole interactions and detuning have a more significant effect on the quality of population inversion than the Kerr effect. Furthermore, for both atom-atom and atom-field entanglement, the data show that dipole-dipole interaction enhances entanglement more strongly than the Kerr effect.
Alaa Almaji; Azadeh Haghighatzadeh
Abstract
This study presents a numerical simulation of the simultaneous effects of electric field orientation and intense laser radiation on the Stark shift phenomenon in intra-band transitions of a heterostructured quantum well with a GaAs/Ga₀.₅₅Al₀.₄₅As quasi-V-shaped potential. The numerical solution ...
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This study presents a numerical simulation of the simultaneous effects of electric field orientation and intense laser radiation on the Stark shift phenomenon in intra-band transitions of a heterostructured quantum well with a GaAs/Ga₀.₅₅Al₀.₄₅As quasi-V-shaped potential. The numerical solution of the Schrödinger equation was performed within the framework of the effective oscillatory potential and the effective mass approximation, and the system's behavior under electric fields with different polarizations (F_z=±25 kV/cm) and various laser field amplitudes (α_0) was analyzed. The findings indicate that the laser field alters the potential configuration by creating a gap in the lower part of the well, changing it from a single-well to an asymmetric double-well configuration. This change is accompanied by a reduction in the effective depth and an increase in the effective width of the potential well, resulting in an increase in the number of bound states and a reduction in level spacings. The results related to the application of the electric field showed that the sign and magnitude of the Stark shift are sensitively dependent on the field direction, such that the inversion of the field direction leads to the inversion of the shift sign in all energy levels. Furthermore, the laser field strength, as an active control parameter, has a determining effect on the magnitude and sensitivity of this shift. These observations prove the existence of a controllable tripartite interaction between the heterogeneous well geometry, the electric field, and the laser field, which can be utilized for engineering optoelectronic properties in nanodevices.
Keivan M. Aghdami
Abstract
Optical spectrometers generally, and specially the compact and miniaturized ones with small dimensions, versatile and resistant due to harsh environments conditions, are highly interested. These apparatuses have wide applications in all scientific and industrial applications in measurement, sensing, ...
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Optical spectrometers generally, and specially the compact and miniaturized ones with small dimensions, versatile and resistant due to harsh environments conditions, are highly interested. These apparatuses have wide applications in all scientific and industrial applications in measurement, sensing, material analysis and optical communication devices. In a novel design for this kind of spectrometers, elimination of the focusing element (lenses) can be established by inscription a chirped Bragg grating directly on a usual optical fiber, promotes further size reduction and increases device toleration against harsh environmental condition. In the present paper, a wave-optics based, diffraction superimposition method is employed for design of appropriate Bragg grating for this structure, then it compared with the results of usual FDTD simulation. The outcome reveals the good agreement respect to FDTD, as well as, extraordinary higher speed in calculation, especially in higher physical sizes. Linear dispersion of spectrum on the one-dimensional array of optical detector and the resolution parameters are calculated by utilizing profits of diffraction method. Also using the curved detectors array instead of plane array is proposed in order to improve wavelength resolving power in miniaturized spectrometer. This design showing acceptable accuracy of 2nm for resolution with resolving power of 250 in whole near-IR, visible and near-UV wavelength domain, has more advantages respect to other miniature spectrometers.
Naser Jahanbakhshi Zadeh; mahmood Borhani Zarandi; Bita Nakhaee; Milad Sani
Abstract
In this study, optical properties of the CH3NH3PbI3 perovskite layer, which was deposited using lead iodide (PbI2) and methyl ammonium iodide (MAI) in DMF and DMSO solvents in a single-step method with chlorobenzene as an anti-solvent, were investigated and analyzed. For this purpose, by applying chlorobenzene ...
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In this study, optical properties of the CH3NH3PbI3 perovskite layer, which was deposited using lead iodide (PbI2) and methyl ammonium iodide (MAI) in DMF and DMSO solvents in a single-step method with chlorobenzene as an anti-solvent, were investigated and analyzed. For this purpose, by applying chlorobenzene as an antisolvent at 7, 10, and 13 seconds after the start of deposition process, the optical parameters of the perovskite layer, including absorption coefficient, direct and indirect optical bandgaps, extinction coeficient, refractive index, optical conductivity, and urbach energy, were calculated. For perovskite layer that antisolvent was applied 10 seconds after the start of the deposition, direct and indirect optical gaps were 1.61 and 1.55 eV, respectively, and for the 7-second sample, they were 1.57 and 1.51 eV, respectively, and for the 13-second sample, they were 1.54 and 1.48 eV, respectively. The urbach energy for the perovskite layer with the antisolvent treatment time of 10 seconds after the start of the deposition process was 0.05 eV, which was lower than the value of this parameter for the 7 and 13 second samples, which were 0.095 and 0.119 eV, respectively, indicating the formation of perovskite crystals with better quality and fewer lattice defects. The results of this research can be used in the design and optical optimization of solar cells with perovskite absorbing layers.
Maryam Eliasi; Ali Mokhtari; Vishtasb Soleimanian
Abstract
Heusler alloys have recently received much attention due to their memory, spintronic properties, and unique application in industry and technology. The structural, electronic, and optical properties of Heusler compounds KYBX (Y=Ca, Sr and X=S, Se) have been studied in this research. The results show ...
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Heusler alloys have recently received much attention due to their memory, spintronic properties, and unique application in industry and technology. The structural, electronic, and optical properties of Heusler compounds KYBX (Y=Ca, Sr and X=S, Se) have been studied in this research. The results show that these alloys are magnetic half-metals with 100% spin polarization at the Fermi level. The half-metal properties, magnetic properties, shape memory effect, magnetothermal, high magnetoresistance, thermoelectric phenomena, etc., have increased the potential of these alloys in the industry. Optical properties also confirm their half-metallic nature. Optical studies of these compounds show that the maximum reflection is in the low-energy (infrared region) and they have high absorption in the ultraviolet region. These compounds work as a reflector for infrared radiation. The presence of a small peak in the visible range of the absorption spectra of the studied materials is one of their interesting features for application in photovoltaic devices.