Optical and Quantum Electronics最新文献

The scattering phenomena can be realized in a variety of everyday situations, including the rainbow pattern after a rainstorm, the dispersion of raindrops, information and communication (ICT) systems, radar cross section (RCS) measurement, and remote sensing. Inspired by the electromagnetic scattering features, this study explores the scattering characteristics of orbital angular momentum (OAM) carried by Gaussian vortex beam (GVB) for perfect electromagnetic conductor (PEMC) sphere by utilizing the generalized Lorenz–Mie theory (GLMT). Stemming from the integral localized approximation (ILA) method, the beam‐shape coefficients (BSCs) representing the incident GVB are obtained. Vortex beams carry distinct unique optical characteristics as compared to the other beam types as these possess OAM. Computations for the efficiencies (scattering and extinction) for a focused GVB are conducted and discussed to analyze the scattering phenomena of the electromagnetic fields outside the PEMC sphere. To ensure the accuracy of the results, scattering efficiency for Gaussian beam and plane wave is computed and compared using the GLMT for PEMC sphere. The OAM mode index, beam waist radius, and the scalar admittance of GVB are chosen as parameters to investigate their impact on the scattering dynamics (i.e., scattering and extinction efficiency). The numerical results show that OAM mode index, beam waist radius, and PEMC admittance have greater impact on optical efficiencies. Nonetheless, the trend of the scattering efficiency decreases irrespective of the extinction efficiency i.e., increases for OAM mode index.

In this manuscript, a theoretical investigation of SPPs generated at magnetized plasma–graphene interface is presented. To model graphene conductivity, Kubo formula is utilized, and impedance boundary conditions are applied to obtain dispersion relation. In the presence of strong anisotropy of the plasma medium, the behaviors of the lower and upper plasmon modes are demonstrated. By examining the dispersion relation, it has been shown that upper and lower modes strongly depend on graphene and plasma features. It has been shown that effective mode index and phase velocity of proposed structure can be tuned by tuning graphene and magnetized plasma features. The proposed model may be exploited for a variety of applications, including sensing and integrated plasmonic circuits in the THz spectrum.

Chikungunya virus (CHIKV) poses a significant public health threat due to its capacity to cause widespread and debilitating outbreaks. The virus is responsible for CHIKV fever, a disease characterized by severe joint pain, sudden onset of fever, headache, muscle pain, and rash. The virus has been reported in various regions globally, with outbreaks occurring in parts of Africa, Asia, the Americas, and the Indian subcontinent. Consequently, the scientific community expends substantial efforts in developing dependable, rapid, highly sensitive, and cost-effective techniques in order to identify the CHIKV virus. In this study, an innovative biomedical sensor using photonic crystal fiber technology enables precise detection of the CHIKV virus through uric acid, normal and infected plasma, red blood cells, and platelets in the blood. The introduced sensor identifies those kinds with extremely increased relative sensitivity and minimal losses in contrast to alternative photonic crystal fiber-based biosensors. The introduced sensor showcases a minimal confinement loss of 2.25 × 10^− 13 cm^− 1, a relative sensitivity of 99.37%, an effective area of 1.36 × 10⁵ µm², with a minimal effective material loss of 0.001966 cm^–1, a numerical aperture of 0.1874, and low dispersion of 0.06. Also, the demonstrated sensor is able to function within the terahertz spectrum, covering a substantial span from 0.8 to 2.6 THz. Furthermore, an extensive comparison analysis is performed between the showcased sensor and related literature on photonic crystal fibers to verify the reliability and effectiveness of the introduced structure.

This study investigates the influence of hydrostatic pressure on structural, electronic, mechanical and optical properties of Sr₃PX₃ (X = Cl and Br) compounds, by using the first-principles density functional theory (DFT) within the pressure range of 0–30 GPa with a span of 10 GPa. For Sr₃PCl₃ and Sr₃PBr₃, the dynamical stability is confirmed by the fact that the phonon dispersion curves do not contain imaginary modes. Pressure-induced band gap alterations in Sr₃PCl₃ and Sr₃PBr₃ reveal semiconducting behavior: GGA measurements show a decrease from 1.70 eV and 1.55 eV at ambient pressure to 0.22 eV and 0.21 eV at 30 GPa; TB-mBJ results show a decrease from 2.73 eV and 2.40 to 1.07 eV and 0.92 eV. This supports their inverse relationship with pressure. The values of Debye and melting temperatures support their high-temperature applications. Effective mass also shows an inverse relationship with induced pressure. The bond length, lattice parameters, and cell volume reduces with pressure. They exhibit ductility, which is further enhanced by the applied pressure. These materials emerge as promising candidates for flexible optoelectronic devices. Optical properties like absorption coefficients, reflectivity, and dielectric functions were observed and found to be significantly influenced by applied pressure. The absorption spectra exhibit a significant redshift with increasing pressure, indicating enhanced potential for optoelectronic applications. Our detailed investigation sheds light on the tunability of Sr₃PX₃ (X = Cl and Br) properties under pressure, showcasing their potential for cutting-edge applications in optoelectronics and photovoltaics.

The aim of this work is to study the optical properties of ZnSe/ZnS non-concentric core–shell quantum dots (CSQDs). The numerical method used in this work is based on a combination of coordinate transformation and finite difference method (FDM) to solve the three dimensions of the Schrödinger equation. The optical properties are obtained using the compact density matrix formalism. The influence of different dimensions of the non-concentric CSQD, the position of a core material and the effect of different values of the incident optical intensity I on the optical properties of the CSQD are investigated. The results obtained indicate that the oscillator strength, absorption coefficient and refractive index changes are strongly dependent on the size of the CSQD. The magnitude of both the total absorption coefficient and the refractive index decreased as the incident optical intensity increased. In addition, the resonance peaks for the absorption coefficient and refractive index changes shift towards higher energies when we move from concentric to non-concentric core–shell quantum dots.

Using the full potential density functional theory (DFT), structural, electronic and optical properties as well as thermodynamic attributes of GaMF3 (M = Ca and Cd) were studied. In this investigation, electronic and optical characteristics were assessed using the (GGA + U) functional whereas the thermodynamic characteristics of the perovskite were assessed using the Gibbs code. The negative formation energy confirms structural stability. Whereas GaCaF3 shows a direct band gap, while GaCdF3 exhibits indirect energy band gap. Density of states plots indicated the presence of mixed ionic and covalent connections. Optical characteristics are predicted in the energy span of 0–12 eV, including reflectivity, refractive index, absorption coefficients, real and imaginary parts of dielectric functions, and optical conductivity. These materials have a small reflectivity and high absorption in the Ultraviolet region, which makes them good candidates for optoelectronic materials. The negative Gibbs free energy indicate that these materials are stable and can be synthesize at room temperature. This work sheds light on the behavior and composition of perovskites for optoelectronic application.

Electronic and optical properties of an exciton in the ZnSe/CdSe/ZnSe quantum well are investigated using the Razavy and Pöschl -Teller confined potentials. The theoretical investigations on exciton binding energy, oscillator strength, radiative lifetime, absorption coefficient and changes of refractive index are focused on the structural parameters of these two potentials. They are carried out using variational method and the matrix density approach. Out of two structural parameters (A and M) in the Razavy potential, M is found to be much more effective than A, similarly, λ parameter is more effective than the other parameter χ in Pöschl-Teller potential. The single quantum well becomes double quantum well when the value of A is less than the value of M. The potential asymmetry is developed if the structural parameters are altered. Further, the optical properties are strongly affected by the geometrical size, changes in the structure and the associated structural parameters. It leads to alter the optical properties drastically in the quantum well. The results are compared with the available literature and we hope that they can be used for the design of potentials for the future opto-electronic devices.

To widen the photo-responsivity range of niobium pentoxide photodetectors, InSe thin films were deposited by thermal evaporation technique under high vacuum pressure and used as substrates for growing Nb₂O₅ thin films. The resulting InSe/Nb₂O₅ (ISNO) stacked layers formed amorphous/amorphous structure. Optical analyses showed that the niobium pentoxide layers successfully suppressed the free carrier absorption observed in InSe substrates. A new direct allowed transitions energy band gap of 0.85 eV was formed at the interface between InSe and Nb₂O₅. The ISNO interfaces exhibited conduction and valence band offsets in the ranges of 0.25–0.65 eV and (1.85-1.47) eV, respectively. Depositing Nb₂O₅ onto InSe extended the light responsivity range of Nb₂O₅ from the ultraviolet to the near infrared range. Notably, ISNO photodetectors displayed impressive features, with large current responsivities and large external quantum efficiencies of 4.7 A/W and 9.7 A/W and 1000% and 3000%, under visible-infrared and ultraviolet radiations, respectively.These characteristics make the ISNO heterojunction devices promising candidates for broadband photodetectors and other optoelectronic applications.

The demand for faster and more reliable wireless communication has led to the emergence of 6G technology. One of the key features of 6G is the utilization of terahertz (THz) frequencies for data transmission, which can provide significantly higher data rates compared to previous generations. By extending the near-field sensing range, the communication distance can be increased, leading to improved coverage and performance in 6G systems. The proposed solution is achieved through the integration of metamaterials, which are artificially designed structures with unique electromagnetic properties. By incorporating metamaterials into the design of THz antennas, we can manipulate the near-field region and enhance its sensing capabilities. Near field enhancement can also be achieved through the use of reflectors, non-uniform spacing, and dielectric lenses. Plasmonic structures and chiral metamaterials are also effective. It is achieved by tailoring the electric and magnetic response of the metamaterials, which can effectively concentrate the THz radiation within the near-field region of the antenna. The proposed model reached 98.23% resolution, 92.51% sensitivity, 93.78% range, 88.58% frequency response, 94.02% directivity, 94.62% cross talk reduction. The enhanced near-field sensing range for THz antennas will have a significant impact on the performance of 6G communication systems. It will not only extend the communication distance but also improve signal quality and reduce power consumption. It will pave the way for the realization of ultra-high-speed and reliable 6G wireless communication, making it a potential game-changer in the future of telecommunications.

The study examines how generalized Ince–Gaussian beams (gIGBs) propagate through oceanic turbulence (OT) by decomposing them into a set of Laguerre–Gaussian beams. The Huygens–Fresnel diffraction integral is utilized to derive an analytical formula representing the average intensity distribution of these beams at the output surface of the OT medium. Detailed numerical results and discussions regarding both beam and medium parameters effects on gIGBs propagation in OT are provided. These findings showcase an examination of gIGBs for underwater wireless optical communication and imaging systems, employing laser light as conduit for transmitting signals.