Optical and Quantum Electronics最新文献

Glasses were prepared using a melt-quenching technique with the following composition: 55 mol% Li₂B₄O₇ and (45-x) mol% Pb₃O₄- (x) mol% CuO, where x takes values of 5, 10, 15, 20 and 25 mol%. Differential thermal analysis (DTA) confirmed the formation of glass, revealing that the glass transition temperature increased from 300 °C to 317 °C as the copper content rose to 20 mol%. However, beyond this point, the glass transition temperature began to decrease. Some samples displayed two glassy phases, as indicated by the presence of two distinct glass transition temperatures. All glass samples demonstrated high thermal stability and effective glass-forming ability, with properties improving as the copper content increased. X-ray diffraction (XRD) spectra confirmed that the samples were amorphous in nature. The structural, optical, and luminescence properties were investigated using Fourier-transform attenuated total reflectance (ATR) FTIR, X-ray photoelectron spectroscopy (XPS), UV/Vis/NIR spectroscopy, and a spectrofluorometer. FTIR spectra indicated that the glass samples contained vibrations from BO₄, BO₃, and PbO₄ groups. As the amount of copper oxide increased, the concentration of non-bridging oxygens (NBOs) also rose. The ratio of BO₄ to BO₃ increased up to 20 mol% of CuO and subsequently began to decrease. According to the XPS results, the ratio of NBOs to bridging oxygens (BOs) increased with CuO content up to 15 mol%, after which it declined. This initial rise suggests an increase in polarization and a loosening of the glass network structure. Additionally, copper ions were present in both Cu²⁺ and Cu⁺ valence states, in line with the optical absorption results. The ratio of Cu²⁺ to Cu⁺ increases to 6 as the concentration of copper rises. As the copper oxide content increased, the optical band gap decreased from 2.9 eV to 1.7 eV. Luminescence from copper ions produced emissions in various colors, including green, greenish-yellow, orange, and pink, depending on the excitation wavelengths, which ranged from 270 nm to 350 nm without a filter. Using a filter, the emissions took on a blue hue at the same excitation energy.

The energy crisis has attracted widespread attention in scientific research, with renewable energy production—particularly through solar cells—considered a promising solution. Over the past decades, numerous studies have focused on the active materials used in solar cells. Investigating the optical properties of these materials is crucial for applications in solar cells, optical filters, and other optoelectronic devices. Traditional methods such as the Schuster–Kubelka–Munk (SKM) remission function and Tauc’s plot are commonly used to estimate the optical band gap; however, they provide only the energy gap value. More comprehensive information—such as the energies of the conduction band, valence band, and Fermi level—is vital for selecting compatible transparent conductive layers. This study presents a novel quantum–classical approach to the well-known quantum mechanics problem of the rectangular potential barrier. Using a Modified Schrödinger Equation, the proposed model directly estimates the energies of the conduction band, valence band, Fermi level in intrinsic semiconductors, and intermediate state (donor or acceptor) involved in indirect transitions, as well as the optical diffusion length and majority carrier type. The model is validated using experimental data and shows a strong correlation between predicted and observed values. It represents a valuable tool for the optical characterization of materials used in solar cells, optoelectronic devices, and optical filters.

In this study, the detection capability of biological threat agents was investigated using a multispectral nanoplasmonic aptasensor based on a Di-supercell metamaterial. This configuration consists of two supercells: one circular and the other square, with a square cell placed inside a circular cell, creating the proposed structure. The three-dimensional finite difference time domain (FDTD) simulation method also confirmed the validity of the findings. The detection of biomolecules in traditional biosensors, especially in the presence of low analyte concentrations, is challenging and requires the use of sensors with superior sensitivity (S). Based on the results obtained, the designed structure exhibits sensitivities of 539.43 and 644.29 nm/RIU in modes I and II. The presence of two resonance modes in this structure makes it an ideal choice for multispectral applications. Our findings suggest that this has structure substantial promise for a variety of biological applications. In this study, both silver and gold metals were evaluated as plasmonic materials. Our novel design features a unique arrangement that allows for maximum interaction of cells with the target analyte. This optimized structure provides a suitable platform for enhancing the sensitivity and accuracy of analyte detection and, given the level of sensitivity, is an appropriate option for the identification of biological threat agents.

We present a photonic-crystal-based rib waveguide design for atom-chip applications that enables robust trapping of ultracold atoms. Using the generalized Effective Index Method (gEIM) together with concepts from “scale-invariant” non-Gaussian photonics, we design a geometry that supports a flat-top attractive mode and an edge-enhanced repulsive mode. The structure, fabricated on a 1D photonic crystal substrate, sustains surface modes at 850 nm (red-detuned, attractive) and 640 nm (blue-detuned, repulsive) with effective refractive indices near unity, yielding extended evanescent penetration into vacuum. This configuration enhances lateral confinement, mitigates atomic losses near the waveguide edges, and removes the need for an auxiliary transverse-control laser. Full-vectorial simulations confirm a stable trap for ultracold rubidium atoms with a depth of 170 µK at a distance of over 865 nm from the surface, minimizing surface-induced effects and providing a compact platform for quantum sensing applications.

This paper explores the properties of a partially coherent modified anomalous vortex beam (PCMAVB) in maritime turbulence. The propagation formula of the PCMAVB through the considered turbulence media has been derived using the extended Huygens-Fresnel integral. Numerical examples are provided to examine how maritime turbulence strength influences the intensity distribution under various initial beam parameter conditions. The results reveal that the PCMAVB maintains its initial profile over short distances; however, with further propagation, the beam gradually loses its properties, evolving into a Gaussian beam in the far field. The rate of increase in the central peak intensity accelerates as the turbulence’s constant structure rises and the turbulence’s inner scale size diminishes, or as beam parameters such as coherence length and topological charge are reduced. Moreover, lower values of the modification parameter δ improve the beam’s resistance to turbulence at short distances. This suggests that the modification parameter introduces a new aspect for controlling the properties of hollow beams. The obtained results may prove useful for practical applications of PCMAVB in free-space optical communications.

In this research, some key issues, such as performance enhancement, impedance matching, and miniaturization, are tackled to design and optimize a compact 38 GHz millimetre wave (mmWave) microstrip patch antenna (MPA) for fifth generation (5G) wireless systems. A Rogers RT5880 substrate (ε_r = 2.2, tanδ = 0.0009) was utilized to design and simulate the designed antenna with an octagonal-shaped patch structure in CST Microwave Studio. Several design turns were applied in order to optimize the electromagnetic performance, including rectangular and hexagonal photonic band gap (PBG) on the substrate as well as patch and ground plane modifications. The design step further comprised machine Learning (ML) algorithms, including Gradient Boosting Model Gain (GBMG) optimization and Support Vector Regression (SVR), trained on 150 and 118 sample datasets, respectively. At 38 GHz, the record antenna stipulated had a return loss of −34.80 dB, a gain of 7.979 dB, a directivity of 8.263 dBi, and a radiation efficiency of 93.65%. The reliability of ML-based optimization can be verified by the SVR model that achieved R2 (prediction efficiency) = 0.987 and by GBM, which achieved an R2 of 0.9667 with Root Mean Squared Error (RMSE) = 0.2896 for gain prediction. Due to the overall stiff structure, high efficiency, and stable radiation property of the proposed ML-assisted antenna prediction, it is more suitable for 5G mmWave applications, including small-cell communication systems and device-integrated communication systems.

The modern development of analytical methods in the field of temperature and pH detection in various media, including biological ones, is associated with the development of luminescent sensors. The indisputable advantage of these sensors is their low invasiveness, remoteness, and the ability to perform intracellular measurements. Moreover, the luminescent properties of such sensors often depend on several environmental parameters: temperature, acidity, presence of active centers, etc. Such a complex dependence can either be an obstacle to the creation of a luminescent sensor due to the uncertainty of the determined values or form the basis for the creation of multimodal sensors for simultaneous registration of several parameters. Water-soluble luminescent molecular plasmon nanostructures based on AuAg core, (hbox {SiO}_2) shell and TMPyP-OTs porphyrin are being developed as a multimodal luminescent sensor for simultaneous precision measurement of pH and temperature. The solubility in water makes these sensors promising in measuring intracellular parameters.

This study examines the influence of lead (Pb²⁺) ions on the optical properties of cadmium–lead–selenium (CdPbSe) alloyed thin films synthesized in an alkaline medium. By systematically varying Pb concentration and deposition time, we demonstrate that Pb is not a passive impurity but actively modulates the bandgap energy. A Pb concentration of 0.03 mol significantly enhances infrared optical transitions, while prolonged deposition reduces the bandgap consistent with quantum confinement effects. Surprisingly, increased deposition time also led to higher Pb incorporation, challenging the assumption that bandgap tuning is governed solely by particle size. Transmission electron microscopy revealed no clear nanoparticle growth, suggesting complex structural dynamics. To avoid model-dependent assumptions, bandgap energies were determined using the Derivative of the Inverse Transmission Method (DITM), a robust alternative to the Tauc plot. These findings highlight the critical role of ionic composition particularly Pb in tailoring the optoelectronic properties of alloyed quantum dots, offering new design strategies beyond size control.

Using first principles, the Mg₈₀Ni₁₀Nd₁₀ metallic glass structure and its mechanics were investigated. We combined density functional theory (DFT) and ab initio molecular dynamics processing. In the melt, a quenched amorphous phase was observed, which was confirmed by normal pressure. Using the Birch–Murnaghan equation-of-state, we obtained a bulk modulus of ~ 65 GPa. It also shows that it is highly stiff and has good structural integrity. The elastic continuous analysis is well within Born’s criteria, indicating isotropy in elasticity; its good ductility (B/G ≈ 2.1) is equally commendable. Vibrational spectra in the visible UV (3–6 eV) were not just absorbed as visible–UV. Still, it also has near-infrared (k ≈ 0) transparency and has been further shown to have potential as a UV-blocking and anti-reflective film. Furthermore, the electronic density-of-states and band-structure data suggest a semi-metallic structure resulting from the hybridization of Mg-sp, Ni-3d, and Nd-4f orbitals, with a high conductivity and a work function of ~ 4.0 eV. Certainly, Mg₈₀Ni₁₀Nd₁₀ is an applicable amorphous alloy for advanced electronic applications, such as optoelectronics, thermal insulation, and shielding films, as it offers mechanical properties, optical flexibility, and electronic compatibility.