Optical and Quantum Electronics最新文献

Concise review explores random lasers, utilizing a scattering medium for optical feedback instead of this the conventional optical cavity found in traditional lasers. Random laser generation relies on gain and dispersion for optical feedback and amplification. Among the myriad of complex nanostructures, surface-based nanomaterials are gaining attention. The materials take the form of core@ shell nanostructures, combining individual properties while maintaining distinct characteristics. In the realm of intelligence research, there is a significant emphasis on synthesizing core@ shell nanoparticles (NPS). Noble metals such as Au, Ag, Pt, and Pd serve as core materials, while metal oxide semiconductors like TiO₂, SnO₂, and Cu₂O act as shell materials. This recent development has sparked considerable interest. The unique arrangement and function of the core and shell lead to diverse applications, including comprehensive photovoltaic systems, color-coded solar cells, and more. Furthermore, these core@ shell nanostructures find applications in random lasers, influencing fields such as medicine and technology. The implementation of random lasers extends to medical imaging devices, displays, sensors, and distinctive sign technologies. As researchers continue to explore the intricate characteristics of core@ shell nanostructures, new trends and opportunities are likely to emerge, promising breakthroughs in various scientific and technological domains.

This paper presents a comprehensive analysis of the ((1+1))-dimensional Klein-Gordan equation which plays a significant role in various areas of theoretical and applied physics. The main focus of this research centers on several key areas. First, infinitesimal generators of symmetries were found by Lie symmetry invariance analysis. Then, using the adjoint representation, an ideal system was created based on the found Lie vectors. Secondly, by utilizing the analytical approach, namely the modified Sardar sub equation method, we systematically derive various novel soliton solution in the form of dark, bright, periodic, singular, combo, hyperbolic as well as mixed trigonometric. Finally, bifurcation analysis is performed at the system’s fixed points, revealing chaotic behavior when an external force is introduced into the dynamic system. To identify the chaotic characteristics, a range of tools, such as 3D and 2D phase plots, time series, Lyapunov exponents, and multistability analysis, are utilized. Additionally, the sensitivity analysis of the model is examined under different initial conditions. These results enhance the understanding of nonlinear wave phenomena in mathematical physics and hold potential applications across numerous scientific disciplines.

In this work, the structural, electronic, elastic, optical and dynamic properties of Li₃Sb and Li₂GaSb crystal structures were researched by using the density functional theory applied in Abinit and Quantum Espresso package programs. All calculations in both programs were performed using the Generalized Gradient Approximation as an exchange–correlation function in Kohn–Sham equations. When the structural properties of the crystals were examined, they were found to be in good agreement with other theoretical results. As a result of the calculations related to the electronic properties, it was determined that the Li₃Sb crystal exhibited semiconducting properties and the Li₂GaSb crystal exhibited metallic properties. Then, focusing on the dynamic properties of Li₃Sb and Li₂GaSb crystals, it was concluded that both crystals are dynamically stable. From the calculations made, it was concluded that the stable state did not deteriorate when pressure was applied to the Li₃Sb crystal, but the stable state deteriorated when pressure was applied to the Li₂GaSb crystal from 528 kbar pressure. In addition, the calculations showed that the thermal conductivity of Li₃Sb is higher than that of Li₂GaSb. By calculating the elastic properties, it was found that Li₃Sb is a brittle material while Li₂GaSb is an elastic material. Finally, based on the semiconductor properties of the Li₃Sb crystal, its optical properties were investigated.

In the framework of the generalized Huygens–Fresnel diffraction integral and paraxial approximation theory, the propagation features of the general model vortex higher-order cosh-Gaussian beam (GMvHchGB) in a free space (FS) and a gradient-index medium (GIM) are studied. The analytical formulas of the GMvHchGB propagating through the considered media are derived. According to the derived formulas, some numerical examples of the normalized intensity distributions and corresponding phase structure of the GMvHchGB in both FS and GIM are performed under different parameter conditions during propagation setups. The obtained results show that the beam with higher decentered parameters, the GMvHchGB propagating in FS case cannot maintain its initial shape during the propagation process, whereas the beam propagation in the GIM case will keep the original shape unchanged with a repeated self-focusing along propagation distances. Finally, the numerical results of both intensity and phase distributions demonstrated that the beam order N significantly influences the vortex property of the beam, which enhances the clear importance of the current work.

The manuscript presents the design and development of a Microwave Hyperthermia (MHT) applicator integrated with an Electromagnetic (EM) lens. The purpose of the proposed MHT applicator is to provide non-invasive microwave hyperthermia treatment for skin cancer. The proposed MHT applicator comprises of an EM lens (133.75 × 133.75 mm³) placed ahead of a Hybrid Fractal Microstrip Patch Antenna (HFMA) (30 × 26 × 1.645 mm³), backed by a Meshedgrid-shaped Artificial magnetic Conductor (AMC) (48 × 48 × 3.27 mm³) reflector at an optimal distance of 16 mm The prototype of the HFMA is fabricated on a Rogers (RT5880) substrate and offers an impedance BW of 278 MHz, for a frequency from 2.316 to 2.594 GHz. To improve the front-to-back ratio (FBR) of the proposed HFMA, an EM lens that reduces the beam width and concentrated the energy in the desired direction is integrated with the AMC-backed HFMA. The final MHT applicator configuration provides a 3 dB beam width of 49.6° and a gain of 7.35 dBi at 2.45 GHz. The testing and validation  of the proposed MHT applicator is carried out in a simulation environment using Computer Simulation Technology (CST) Multiphysics for thermal analysis to check the temperature rise in the phantom. An in-vitro sample of skin phantom with a tumor is prepared using chemicals mimicking skin properties is exposed to the EM radiations emitted by the proposed HT applicator excited using a RF signal generator and power amplifier. the temperature rise in the phantom is recorded using optical temperature measurement probe. A temperature rise in the cancer-affected area up to 44 °C (Effective Temperature Area (ETA) 36 × 20 mm²) is observed in the simulation environment for an exposure time of approx. 45 min and in the measurement environment after a span of 25 minuites. A reported Specific Absorption Rate (SAR) value of 10 W/Kg shows that the proposed MHT applicator is safe for human exposure, and also reduces hot spots by enhancing the focus with controlled temperature, thus making the proposed applicator safe for human exposure.

In the present investigation, vanadium-doped zinc oxide (V: ZnO) thin films were synthesized by the sol-gel dip-coating technique by varying the percentage of V. Raman spectroscopy was used for structural conformation, showing the making of an impurity phase on increasing the V doping whereas, SEM analysis revealed that increasing the vanadium (V) concentration surface gets smoothen. The V incorporation into the ZnO crystal lattice was confirmed by the EDS analysis. The 3-D surface topography and stereometric analysis show the 3-D surface texture parameters that affect the optical and electrical features of the material. The results from experimental measurements suggest that V: ZnO thin films prepared at 3% V had the most suitable surface in terms of roughness, texture, and waviness. UV analysis showed a decrease in E_g value with an increase in the doping percentage, the optical parameters such as absorption and transmission (%) were also analyzed. The electrical properties were studied using I-V measurements from which resistivity for doped ZnO films was found to significantly decrease and increase its current densities. In photovoltaic characteristic evaluation, the efficiency (η) was attributed to variation in the value of J_sc. The C-3 coated PV cells had superior J_SC at 36.70 mA/cm², resulting an increased overall efficiency without changing the open-circuit voltage or fill factor. Thus, 3% doping concentration has a favourable influence on PV cell performance, indicating a possible path for improving energy conversion efficiencyby ~ 11.76% with better stability. This material can be proven as a good coating-absorbing layer for PV cells.

A multi-wavelength actively Q-switched random fiber laser based on real-time configurable Waveshaper and electro-optic modulator is proposed and experimentally demonstrated. The random feedback of the laser is provided by Rayleigh scattering generated by the single-mode fiber. The Waveshaper not only acts as a multi-channel filter, but also introduces wavelength-dependent losses in the laser cavity, which can suppress the mode competition caused by uniform broadening of the erbium-doped fiber and the power imbalance caused by Rayleigh scattering. Additional dispersion, group delay, phase and other parameters can be introduced through Waveshaper, and then the influence of additional quantities such as dispersion on actively Q-switched random fiber laser is studied. In the experiment, when the additional dispersion changes within -200 ~ 200 ps/nm, the pulse width of actively Q-switched can change between 1.01 ~ 1.18 μs. Compared with other experiments, this experiment further and more accurately studied the effects of dispersion, group delay and phase on actively Q-switched pulses. Because of the half-open cavity and erbium-doped fiber gain, the laser threshold is suppressed to 25 mW. The powers distribution on the wavelengths are uniform, and the amplitude difference between the ten wavelengths is < 2 dB. The side-mode suppression ratio of the laser after equalization is about 25 dB. When a triangle waveform is applied to the EOM, a dark pulse sequence output can be obtained. The proposed multi-wavelength actively Q-switched random fiber laser has the advantages of simple structure, low threshold and high stability.

The effect of Mg substitution on the structural, morphological and electrical properties of sprayed magnesium cobalt oxide (Mg_xCo_3-xO₄) thin films (0 ≤ x ≤ 1) have been studed using X-ray diffraction (XRD), scanning electron microscopy, compositional analysis with EDS technique and four probe method for the electric conductivity measurements. XRD evaluation exhibits that Mg_xCo_3-xO₄ thin films are polycrystalline with spinel cubic structure. The EDS study confirms the presence of Mg and Co in the substituted films with the same concentrations as in the starting solution confirming the formation of Mg_xCo_3-xO₄ thin films. The effect of temperature on the dc conductivity reveals that the electrical transport mechanism in Mg_xCo_3-xO₄ thin films is based on the three-dimensional Mott’s variable-range hopping model. The density of states, the hopping distance, and the hopping energy have been successfully evaluated.

The stack of copper (Cu), tin (Sn), and sulfur (S) precursor layers was deposited on a Corning 2947 substrate using the thermal evaporation method under a vacuum of approximately 2 × 10^–4 Pa, employing the sequentially evaporated layer deposition (SELD) technique. The as-deposited stack was annealed at 623–723 K under a vacuum of approximately 2 × 10⁻¹ Pa to achieve the Cu₃SnS₄ phase. The stack exhibits amorphous behaviour, while films grown between 623 and 723 K attain nanostructured Cu₃SnS₄ (CTS) form. The influence of T_A on the characteristics of the Cu₃SnS₄ layers was investigated through structural, morphological, compositional, optical, and electrical analyses. The annealed CTS films crystallize in a tetragonal crystal system with the space group I42 m (121). The grown films exhibit granular structures, with particles synthesized at 673 K demonstrating increased size. The bandgap (E_g) of the films decreases from 2.13 eV to 1.78 eV, while the absorption coefficient (α) ranges from 1 × 10⁵ to 3 × 10⁵ cm⁻¹, as the annealing temperature (T_A) increases from 623 to 723 K. At 673 K, the low resistivity of 9.37 × 10⁻³ Ω-cm, high mobility of 56.4 cm²/V-s, and acceptor concentration of 1.19 × 10¹⁹ cm⁻³ result from the increased crystallite size, which reduces grain boundary scattering. Thus, Cu₃SnS₄ is a promising absorber layer for thin-film solar cells due to its tunable bandgap, high optical absorption, low cost, and the use of earth-abundant elements. This study successfully advances photovoltaic technology by developing an economically viable alternative material for solar cell absorber layers, paving the way for large-scale solar cell production.