Optical and Quantum Electronics最新文献

The field of photonics has experienced significant progress due to the exploration and integration of machine learning techniques that can be used to model complex electromagnetic behavior as a function of wavelengths and design parameters. Data samples are extracted from electromagnetic simulators, and the resulting data are used by machine-learning algorithms to build efficient and accurate surrogate models that can be used to speed up design tasks. In this work, we propose a novel hybrid technique that integrates supervised and unsupervised learning. The wavelength variable is included in the input space of the design parameters, and a clustering approach identifies a set of wavelength intervals. This interval information is assigned to a categorical variable and encoded as an input. Finally, a supervised deep learning model is built to link the input space with the electromagnetic behavior of interest. We also explore how including physics-informed regularization smooths the model’s predictions. Extensive numerical experiments validate the method.

Acetone detection is essential in industrial, pharmaceutical, and environmental applications due to its toxicity at elevated concentrations. This study reports the fabrication and optical analysis of a D-shaped fiber optic sensor coated with indium tin oxide (ITO, 10 nm), gold (Au, 40 nm), and bilayer Au: ITO (40:10 nm) thin films for room-temperature acetone sensing. The D-shaped geometry was produced via controlled mechanical polishing, while thin films were deposited using high-vacuum electron-beam evaporation. The sensing mechanism is governed by evanescent-field absorption and wavelength-resolved spectral modulation induced by acetone adsorption. Under static testing conditions across 0–870 ppm, the ITO coating achieved a sensitivity of 16 at 350 ppm (LOD = 66 ppm), Au exhibited 14 at 350 ppm (LOD = 75 ppm), and Au: ITO demonstrated 10.2 at 700 ppm (LOD = 205.9 ppm). The bilayer structure enhanced spectral stability at higher gas concentrations. The proposed low-cost, compact, and non-electrical configuration demonstrates strong potential for selective, real-time acetone vapor monitoring in industrial and environmental settings.

Molybdenum disulfide (MoS₂) thin films have emerged as highly promising materials for next-generation electronic and optoelectronic applications owing to their exceptional electronic tunability, strong light-matter interactions, and compatibility with large-area fabrication. While pristine MoS₂ typically exhibits intrinsic n-type conductivity, nitrogen doping provides an effective means to tailor its electronic structure and induce stable p-type behavior. In this work, nitrogen-doped MoS₂ thin films were successfully fabricated using a simple, cost-effective, and scalable spray-coating approach, enabling uniform doping over large areas under mild processing conditions. Comprehensive structural characterization confirms the polycrystalline nature of the films and the coexistence of mixed-phase 1T (metallic) and 2H (semiconducting) MoS₂, whose relative proportions evolve systematically with nitrogen incorporation. X-ray photoelectron spectroscopy evidences efficient nitrogen incorporation, up to 4.83 at%, via substitutional and interstitial mechanisms, resulting in local lattice distortion and partial 1T-phase stabilization. Electrical characterization of back-gated field-effect transistors based on the as-deposited films reveals a clear transition to p-type conduction, with a maximum hole mobility of 3.1 cm²·V⁻¹·s⁻¹. The results demonstrate that nitrogen incorporation effectively modulates the band structure and carrier type in MoS₂ while maintaining film integrity. This study establishes nitrogen doping via spray coating as a practical and scalable route to engineer the conduction type and electronic properties of MoS₂, paving the way for its integration into low-cost, flexible, and large-area 2D electronic and optoelectronic devices.

This study explores the synthesis and properties of two newly developed di-anchoring organic sensitizers featuring quinoxaline acceptors for dye-sensitized solar cells, employing Density Functional Theory (DFT) and its time-dependent counterpart (TD-DFT). The aim is to evaluate their capacity to deliver promising photovoltaic performance alongside significant nonlinear optical (NLO) properties, which hold potential for optoelectronic applications. Comprehensive computational analyses were undertaken, including assessments of HOMO-LUMO characteristics, UV absorption spectra, density of states (DOS), molecular electrostatic potential (MEP), and reduced density gradient (RDG) mapping for the innovative sensitizers. The HOMO and LUMO energy levels were analyzed to highlight their critical role in enhancing electron injection efficiency and facilitating dye regeneration. Key parameters such as energy gaps (Eg) and open-circuit photovoltage (Voc) were examined to glean insights into the chemical reactivity of the studied molecules. Moreover, studied quinoxalines demonstrated high dipole moments, strong linear polarizabilities, and noteworthy hyperpolarizabilities, indicating their potential as efficient NLO materials. The findings spotlight these organic sensitizers as viable candidates for integration into dye-sensitized solar cells while underscoring their performance capabilities in NLO applications. This research contributes to the systematic development of advanced dyes, offering a pathway to further improving DSSC efficiency.Unlike earlier quinoxaline-based sensitizers that predominantly utilized alkoxy or short thiophene π-bridges, the current dyes incorporate extended conjugation and more robust electron-withdrawing substituents on the quinoxaline acceptor. These advancements lead to a deeper LUMO level, greater electron injection driving force, and enhanced light absorption in the visible spectrum. The synergy of structural planarization and refined electronic properties sets these sensitizers apart from prior designs, resulting in higher predicted Voc values and superior interfacial charge transfer performance.

In the field of research on the interaction between electrons and laser pulses, existing studies focus on the radiation characteristics under specific parameter conditions. However, research into the effects of a wider range of parameter changes is lacking. Within the classical electromagnetism framework, this paper employs numerical simulation methods to systematically investigate the influence of electron initial energy variations on the radiation characteristics produced during their cross-collisions with Gaussian laser pulses. Meanwhile the relationship between the peak radiated power of electron and the beam waist radius, the electron emission position and the initial energy of the electron is analyzed. The temporal distribution, spatial distribution and frequency spectrum of electron radiation is also compared and analyzed. The results show that under tight focusing conditions of the laser pulse, the radiation of moderate-energy electrons exhibit asymmetry, and the asymmetry of the radiation gradually weakens as the electron initial energy and the laser beam waist radius increase. For moderate-energy electrons, the rise in initial energy results in a rise in the peak radiated power of electron and a broadening of the spectral band pass. This study focuses on how the initial energy of electron affects nonlinear Thomson scattering, providing a new perspective for studying the cross-collision between electrons and the laser pulse.

This article investigates the propagation characteristics of magneto-optic cylindrical waveguides, focusing on their potential for developing optical isolators through the distinct propagation behaviors in forward and backward directions. By analyzing the interaction of light with magneto-optic materials, it is shown how intrinsic asymmetry can be utilized to achieve effective isolation. A modified cylindrical waveguide structure is proposed, which enhances isolation performance, achieving an isolation ratio of 12 dB with an insertion loss of 3.8 dB at a wavelength of 1550 nm. The results provide deeper insight into the mechanisms governing wave propagation in magneto-optic systems and pave the way for practical implementations in optical communication and signal processing. This work highlights the potential of custom-engineered cylindrical waveguides for advancing magneto-optical device technologies.

This study presents a hybrid wavelength-division-multiplexing passive optical network (WDM–PON) architecture incorporating free-space optical (FSO) transmission to enable flexible short- and long-reach fiber connectivity. To enable bidirectional WDM FSO traffic transmission, the available wavelength band can be divided into four windows to mitigate Rayleigh backscattering-induced interferometric noise. Moreover, the proposed FSO–PON network can provide the short and long-reach fiber-FSO signal transmission simultaneously through same distributed fiber path. In the measurement setup, 24 WDM wavelengths are allocated across four distinct bands, which are interchangeable for both downlink and uplink transmission. Each band supports transmission over fiber spans ranging from short- to long-reach distances. Here, the performance of each FSO wavelength is systematically characterized and discussed. Furthermore, the power sensitivity obtained for each WDM FSO signal under the forward error correction criterion indicates that the redundant power budget is adequate to sustain reliable wireless FSO transmission.

New features of localized state formation near nonlinear planar defect are found and analyzed. Equations modeling a thin-film slab structure with nonlinear properties separating gradient crystal with a hyperbolic profile of the refractive index and the Kerr nonlinear crystal, which can be considered as a planar optical waveguide, are formulated. The problem use the nonlinear Schrödinger equation where the propagation constant is the eigenvalue corresponding to the transverse electric field distribution (the wave function). The exact solutions to the formulated problem and dispersion equations describing the localized and excited states in the cases of self-focusing and defocusing nonlinear responses of the Kerr nonlinear crystal are obtained. Combinations of defect parameter signs, in which an increase or decrease in the depth of field penetration into crystals is observed, as well as a change in the magnitude of its intensity are indicated. The influence of the hyperbolic gradient profile parameters on the dispersion curves and the shape of the spatial distribution of the field are described.

To enhance the transmission capacity and security of confidential optical communication systems, this paper proposes and demonstrates a multi-channel random chaotic encryption scheme that adopts the wavelength division multiplexing (WDM) concept solely for parallel chaos generation. Unlike conventional WDM communication systems, our approach utilizes a WDM-structured array of chaotic carriers for encryption but does not rely on WDM for the underlying data transmission. A single dual-laser source with optical feedback is used to generate a complex chaotic seed, which is then demultiplexed and modulated to form multiple encrypted channels. This architecture enables dynamic random encryption across these independent channels, significantly expanding the key space. Simulation results show a stable 40 Gbit/s OOK signal encryption over 100 km, with excellent error rate optimization and robustness under challenging conditions, such as parameter mismatch conditions and supercritical conditions. The proposed multi-channel architecture surpasses traditional single-channel chaotic communication systems by enhancing both communication capacity and confidentiality. This research lays the groundwork for applying chaotic optical communication in complex settings, with potential uses in military communications, intelligent sensing networks, and future 6G technology.

Janus 2D materials attract significant scientific interest because of their unique physical properties. This article uses first-principles calculations to present a novel class of Janus monolayers XMoYH (X = S, Se, Te; Y = N, P, As) and systematically explore their electronic, spintronic, and optoelectronic potential. Cohesive energy and phonon calculations confirm the stability of all nine possible XMoYH monolayers. SMoNH is the most stable, with the lowest cohesive energy of − 8.18 eV. All studied monolayers exhibit semiconducting behavior, with PBE bandgaps of 1.02–1.92 eV and HSE-calculated gaps of 1.37–2.36 eV. A pronounced electrostatic potential asymmetry (Δϕ = 0.71–2.77 eV) is observed across the thickness of the Janus monolayers. Janus XMoYH monolayers exhibit Zeeman and Rashba spin splittings near K/Γ points due to Mo’s d-orbital spin-orbit coupling and asymmetric structure, making them promising for valleytronics and spintronics. XMoYH monolayers also exhibit strong absorption capabilities, with coefficients reaching up to 3 × 10⁵ cm⁻¹ in the visible range and as high as 7 × 10⁵ cm⁻¹ in the near-ultraviolet region. Driven by strong light absorption, the potential of XMoYH monolayers as p–i–n photodetector channels is investigated. SMoNH, SeMoNH, and SeMoAsH show peak photocurrent densities of 40.5, 22.2, and 14.4 A/m² for near-UV detection, while TeMoAsH, with 7.1 A/m², is promising for infrared detection. In addition, the XMoYH p–i–n photodetectors exhibit peak photoresponsivity (R_ph) between 0.23 and 0.64 A/W, underscoring the significant promise of the proposed monolayers for use in photodetection devices.