Optical and Quantum Electronics最新文献

Graphene-based metamaterial absorbers are increasingly popular for developing various reconfigurable and electrically tunable optical devices, especially in the terahertz (THz) range. This paper aims to design a broadband THz metamaterial absorber (MMA) based on graphene. The proposed absorber consists of a patterned graphene surface layer, a dielectric layer, and a bottom metallic film. The patterned graphene surface layer is composed of two parts with different slots to induce multiple plasmonic resonances. CST simulation results show that the bandwidth with an absorption efficiency exceeding 95% is 3.12 THz, ranging from 4.01 to 7.13 THz. We validated the simulation results using multi-reflection interference theory. To explore the physical mechanisms of broadband absorption, the distribution of the surface electric field in the structure was studied. We also found that the absorber exhibits polarization insensitivity and wide-angle incidence characteristics. The absorption frequency of the absorber can be tuned by changing the chemical potential of graphene. Some notable features of the proposed absorber include the maximum bandwidth and minimal unit cell size of a single-layer absorber without sacrificing polarization insensitivity or amplitude tunability. Besides, the absorber has a thickness of 7.2 μm and a unit cell period of 4 μm, thus its structure is very compact in comparison with most previous MMAs. This proposed MMA has potential applications in terahertz detection, filtering, imaging and stealth technology.

Graphene and iron oxide nanocomposite materials attracted significant attention in different disciplines including optoelectronics, catalysis, and energy conversion/storage devices. Despite the extreme potential, a major obstacle had been the lack of effective and environmentally benign production techniques for mass-producing iron oxide-graphene nanocomposites. To overcome the obstacle, we opted for an efficient, facile, and eco-friendly hydrothermal synthesis route for the synthesis of iron oxide-graphene nanocomposites. The technique involved the homogenous mixing of metal salt precursor (iron chloride), and graphene oxide (GO) followed by a hydrothermal reaction under normal conditions. The synthesized nanocomposites were systematically investigated for structural, morphological, thermal, optical, and magnetic characteristics using XRD, Raman, SEM, TGA, UV–Vis, PL, and VSM techniques. The XRD and Raman studies confirmed the formation of α-Fe₂O₃-RGO and Fe₃O₄-RGO nanocomposites. The SEM images disclosed the anchoring of metal oxide nanoparticles to graphene nanosheets. The nanocomposite exhibited enhanced thermal stability compared to the pristine GO sample. The optical studies corroborated the better charge transfer response of nanocomposites and Hall effect measurements affirmed these nanocomposites as charge transport materials. The VSM measurements confirmed the magnetic behavior of the samples. Therefore, these nanocomposite materials could be a viable option for optoelectronics and energy conversion/storage devices.

First-principles calculation was performed to explore the electronic structures and optical properties of transition metals (TM) doped SnO₂ (TM=Mo, Ru, Rh, Pd, Ag), with the expectation of enhancing the performances of SnO₂-based optical devices. The impacts of different initial-spin settings on the structure were tested and we find it does not affect the average net charge of Sn and O. After selecting a suitable doping concentration, Sn_0.9375TM_0.0625O₂, we confirmed the stability of all doped systems using the formation energy analysis, find that Mo-doped SnO₂ is the easiest to produce and Mo elements has the highest solubility. Analysis based two different calculation methods (GGA-PBE and HartreeFock Hartree-Fock) shows that all doped systems are direct-gap semiconductors and the band gap (spin up/spin down) is reduced comparing with the intrinsic. In the visible light region, all doped systems’ optical absorptions are red-shifted to lower-energy region comparing with pure. The reflectivity of Ag-doped SnO₂ has the most excellent performance enhancement in the infrared region, indicating that have the potential for application of anti-infrared radiation electronic devices. Our study provided the theoretical foundation for the directional design and preparation of SnO₂-based microelectronic and optoelectronic devices.

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The following work presents a theoretical study on new quaternary Heusler compounds called TaAlCuCo under varying pressures from 0 to 100 GPa. The study comprehensively investigates the material's structural, elastic, mechanical, electronic, optical, and vibrational properties. The results reveal that as the applied pressure increases, the lattice parameters of TaAlCuCo decrease from 6.058465 to 5.476836 Å. Furthermore, the material exhibits desirable characteristics such as ductility, metallic bonding, and stability even under high pressure. Notably, TaAlCuCo demonstrates anisotropic behavior, indicating that its properties vary depending on the measurement direction. The study also observes a widening of the material's bandgap from 0.010 to 0.333 eV with increasing pressure, suggesting a decline in conductivity. Additionally, TaAlCuCo exhibits favorable optical properties, including a high refractive index, absorption, reflectivity, and conductivity, thereby indicating its potential as a UV filter and for use optoelectronic devices.

A sensor for the detection of glucose concentration in aqueous medium based on Tamm-Fano resonance is proposed in this research article. The presented sensor configuration mainly comprises of a thin layer of copper on top of a Distributed Bragg Reflector. Alternating layers of Gallium Arsenide with a high refractive index and Silicon dioxide with a low refractive index form the Distributed bragg reflector, respectively. For the detection of analyte such as glucose, a liquid cell has been introduced in between the Cu and Distributed bragg reflector structure. We used Ansys Lumerical software to analyse the sensor's near-infrared reflection spectrum (1000–2400 nm). The proposed sensor structure achieved a Sensitivity, Quality factor, Figure of Merit and Detection Limit of 831.32 nm/RIU, 152.52, 88.91 RIU⁻¹ and 10^–3 RIU, respectively. The proposed sensor structure shows promising results compared to the designs reported in the literature. The present study will be extremely useful for active and passive optoelectronic miniature devices in the future, making the proposed structure valuable not only for glucose detection but also for detecting a wide range of biomolecules and for gas sensing.

The celebrated Hirota equation has important applications in nonlinear optics and quantum physics. This paper proposes a new type of time-varying spectral Hirota (tvsH) equation with variable coefficients and constructs its soliton solutions by extending the Riemann–Hilbert (RH) method. Specifically, Lax representation of the tvsH equation is first provided, which consists of time-varying spectral matrices, and the corresponding RH problem is further established by analyzing the Lax pair. Then, by combining inverse scattering and the spatiotemporal evolution of matrix vector solutions, an explicit expression for n-soliton solution of the tvsH equation is constructed in the absence of reflection potential. In addition, the collision soliton dynamics of the tvsH equation under isospectral and non-isospectral conditions are analyzed by modulating the time-varying coefficients. Most importantly, through the dynamic analysis of single and double solitons in the tvsH equation, we discover some new waveforms that have never been reported before, such as oscillating parabolic solitons and amplitude parabolic variation solitons. These waveforms may have significant theoretical and practical implications.

This research explores the use of laser-induced breakdown spectroscopy to detect elements in water residue. This research focuses on inducing plasma on pelletized water residue samples via a pulsed Neodymium-doped yttrium aluminum garnet (Nd:YAG) nanosecond laser with a wavelength of 1064 nm and energy of 100 mJ. The LIBS measurements were performed without and with a magnetic field of 0.8 T. Magnetic discs were used to create a magnetic field of 0.8 T. The presence of different elements (Ca, Mg, Fe, Cr, Mn, As, C, Li, Sr, Ba, Ti, K, O, N, and Si) was confirmed by examining the plasma emission spectra obtained from LIBS analysis. The results show that LIBS successfully detected toxic and heavy metals in water residues. Notably, the presence of a magnetic field affects the plasma properties such that the electron temperature and electron number density increase with increasing magnetic field. The Joule heating effect and the magnetic confinement effect are responsible for the increase in the plasma properties. The improved spectroscopic outcomes are associated with the magnetic confinement of water residue plasma, supported by the affirmation of thermal beta β_t, which is less than one for all samples.

This research provides a comprehensive investigation of the double perovskite compound Ba₂CrWO₆, emphasizing its structural, electronic, magnetic, thermal, optical, and elastic properties. Analysis revealed that Ba₂CrWO₆ exhibits a direct half-metallic gap of 1.05 eV along the (X–X) direction, accompanied by a net magnetic moment of 2.00 μ_B, significantly influenced by the presence of chromium. In terms of optical characteristics, Ba₂CrWO₆ demonstrated high absorption rates, indicating its potential applications in optical devices, particularly in ultraviolet (UV) light detection, photodetectors, and UV lasers. Furthermore, the elasticity study indicated that this compound possesses weak brittleness, facilitating handling during manufacturing processes. Density Functional Theory (DFT) calculations, using the full-potential linearized augmented plane wave (FP-LAPW) method, employed the generalized gradient approximation (GGA), modified Trans-Blaha (TB-mBJ) approach. Additionally, the GGA + U method, which includes the Hubbard correction term (U), was utilized to address strong electron correlation effects within the compound. The spin–orbit coupling (SOC) was included to see its effects on the total and partial densities of states, but the results are almost similar to calculations without spin orbit coupling.

During the past decades, group-III nitrides have emerged as a new impetus for the development of semiconductor industry and attracted significant attentions in different fields. Among them, indium-bearing group-III nitrides, such as InGaN, InAlN and their quaternary alloy InAlGaN show an adjustable bandgap in wide range including visible spectrum and ultraviolet spectrum, and their excellent electronic properties have been predicted by theoretical calculations. Therefore, indium-bearing group-III nitrides demonstrate great potential as solid lighting and photoelectric detection materials. However, the growth of high-quality indium-bearing group-III nitrides is hindered by the phase segregation of indium component and the lattice mismatch between substrate and epitaxial layer. Tremendous efforts have been paid to solve these issues, and remarkable results have been achieved accordingly. This review mainly focuses on the impressive results of theoretical calculation on properties of indium-bearing group-III nitrides and the breakthroughs in their epitaxial growth, together with the development of electron devices and photoelectric devices based on indium-bearing group-III nitrides. Based on the recent progress, the prospective for the future evolution of indium-bearing group-III nitrides and devices is speculated ultimately. This review provides a guideline for better understanding of the development of indium-bearing group-III nitrides and devices.

First-principles computations have been employed to investigate the structural, electronic, magneto-optical, and elastic features of Half-Heusler compounds Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) by implementing the FP-LAPW technique in the WIEN2K software. The electronic features (DOS and band dispersions) have been explored, considering the tight association between the d/f-states of Ni/Ho/Zr-atoms. The results calculated by GGA + U approximation indicate that Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) exhibit metallic properties. The ({varepsilon }_{2}(omega )) spectra demonstrate that Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) exhibit substantial photon absorption throughout a wide range of energies (∼1.0 to ∼6.0 eV). These compounds have low reflectivity towards incident photons and reflect around 45% of incident photons throughout the full energy spectrum. Ho_1-xZr_xNiSb (x = 37.5%) exhibit the highest magnetic moment among Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) due to hybridization of Ho [({4f}^{11})], Ni [({3d}^{8})], and Zr [({4d}^{2})] localized orbitals. These materials have great potential as candidates for future spintronic applications. Moreover, it has been observed that these half-Heusler compounds possess mechanical stability as they satisfy the Born stability criterion. The mechanical features of Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) are analyzed using elastic metrics such as Pugh’s ratio and Young’s modulus. Furthermore, the examination of Pugh’s ratio and Cauchy's pressure reveals that these half-Heusler compounds exhibit a brittle nature.