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Band-like electron transport in 2D quantum dot periodic lattices: the effect of realistic size distributions
摘要： Electron mobility in nanocrystal films has been a controversial topic in the last few years. Theoretical and experimental studies evidencing carrier transport by hopping or showing band-like features have been reported in the past. A relevant factor to analyze transport results is the progressive improvement leading to better regimented structures for which band-like transport would be more relevant. This work presents an efficient model to compute temperature-dependent band-like electronic mobilities in 2D quantum dot arrays when a realistic quantum dot size distribution is considered. Comparisons with experimental results are used to estimate these size distributions, in good agreement with data of the samples.
关键词： quantum dot arrays,size distribution,band-like transport,electron mobility,nanocrystal films
更新于2025-09-12 10:27:22
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Robust Ultrashort Light Bullets in Strongly Twisted Waveguide Arrays
摘要： We introduce a new class of stable light bullets that form in twisted waveguide arrays pumped with ultrashort pulses, where twisting offers a powerful knob to tune the properties of localized states. We find that, above a critical twist, three-dimensional wave packets are unambiguously stabilized, with no minimum energy threshold. As a consequence, when the higher-order perturbations that accompany ultrashort pulse propagation are at play, the bullets dynamically adjust and sweep along stable branches. Therefore, they are predicted to feature an unprecedented experimental robustness.
关键词： ultrashort pulses,stability,twisted waveguide arrays,three-dimensional wave packets,light bullets
更新于2025-09-12 10:27:22
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Fault diagnosis method of photovoltaic array based on support vector machine
摘要： Photovoltaic (PV) arrays are prone to various faults due to the hostile working environment. This paper presents the fault diagnosis algorithm based on support vector machine (SVM) to detect short circuit, open circuit, and lack of irradiation faults that occurred in PV arrays. By analyzing these faults and I–V characteristic curves of PV arrays, the short-circuit current, open-circuit voltage, maximum-power current, and maximum-power voltage are chosen as input parameters of SVM-based fault diagnosis algorithm. The data pre-processing methods are used to improve the quality of fault data set considering the effects of the quality on the performance of SVM-based fault diagnosis algorithm. The grid search and k-fold cross-validation methods are proposed to optimize the parameters of the SVM-based fault diagnosis algorithm. It gets test accuracy of 97% by testing the trained SVM-based fault diagnosis algorithm with 400 data. The experimental results indicate that the SVM-based fault diagnosis algorithm has higher accuracy and generalization ability than other algorithm for fault diagnosis of PV arrays.
关键词： k-fold cross-validation,PV arrays,data preprocessing,grid search,SVM-based fault diagnosis algorithm
更新于2025-09-12 10:27:22
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Mode Engineering in Linear Coherently Coupled Vertical Cavity Surface Emitting Laser Arrays
摘要： The supermode tuning of coherent 3×1 vertical-cavity surface-emitting laser arrays are characterized and simulated. The array elements are resonantly tuned to achieve coherent operation using selective current injection. Depending on the electrical bias, multiple coherent supermodes are observed above threshold. An effective index model is developed to account for the variable current injection and to simulate the supermodes of the linear array. Agreement between experimental near-field and far-field coherent modes and our model simulations are found both at and above lasing threshold.
关键词： semiconductor laser arrays,Laser modes,phased arrays,vertical cavity surface emitting lasers (VCSELs)
更新于2025-09-11 14:15:04
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Size effect of metal nanodome arrays on performance of plasmonic biosensor
摘要： Size effect of metal nanodome arrays on performance characteristics of a plasmonic biosensor is investigated using reflection spectroscopy. Ag and Au nanodome arrays are created by a bottom-up nanofabrication process by which the dome diameter and metal thickness can be controlled. Reflectivity measurements of metal nanodome arrays showed that the wavelengths and width of resonance dip were changed by the dome diameter and metal thickness, respectively. Bulk refractive index (RI) sensing and detection of DNA hybridization were performed to characterize the sensing performance of metal nanodome arrays. Bulk RI sensitivity were significantly improved as the dome diameter enlarged from 100 to 500 nm. In contrast, metal nanodome arrays with smaller diameter exhibited higher sensor signals against the immobilization of DNA modified gold nanoparticles used for signal amplification indicating strong plasmonic coupling effects. With respect to the dome diameter, the effect of metal thickness was moderate for the presented sensing scheme.
关键词： plasmonic biosensor,metal nanodome arrays,bulk refractive index sensitivity,DNA hybridization,reflection spectroscopy
更新于2025-09-11 14:15:04
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Computer Aided Patterning Design for Self-Assembled Microsphere Lithography (SA-MSL)
摘要： In this paper, we use a finite difference time domain solver to simulate the near field optical properties of self-assembled microsphere arrays when exposed to an incoherent light source. Such arrays are typically used for microsphere lithography where each sphere acts as a ball lens, focusing ultraviolet light into an underlying photoresist layer. it is well known that arrays of circular features can be patterned using this technique. However, here, our simulations show that additional nanometer scale features can be introduced to the pattern by optimising the sphere dimensions and exposure conditions. these features are shown to arise from the contact points between the microspheres which produce paths for light leakage. for hexagonally close packed arrays, the six points of contact lead to star shapes in the photoresist. These star shapes have subfeature sizes comparable to the current achievable resolution of low-cost fabrication techniques.
关键词： finite difference time domain solver,microsphere arrays,SA-MSL,photoresist,Self-assembled microsphere lithography
更新于2025-09-11 14:15:04
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Rapid Biofilm Elimination on Bone Implants Using Near‐Infrared‐Activated Inorganic Semiconductor Heterostructures
摘要： Bacterial infections often cause orthopedic surgery failures. It is hard for the immune system and antibiotics to clear bacteria adhered to implants after they form a mature biofilm, and a secondary surgery is required to remove the infected implants. To avoid this, a hybrid coating of Bi2S3@Ag3PO4/Ti is prepared to eliminate biofilm using near-infrared (NIR) light. Bi2S3 nanorod (NR) arrays are prepared on titanium (Ti) implants through hydrothermal methods, and Ag3PO4 nanoparticles (NPs) are loaded on Bi2S3 NR arrays using a stepwise electrostatic adsorption strategy. The introduction of Ag3PO4 NPs enhances the photocatalysis performances of Bi2S3, and the hybrid coating also exhibits good photothermal effects. After 808 nm light irradiation for 15 min, it shows superior bactericidal efficiency of 99.45% against Staphylococcus aureus, 99.74% against Escherichia coli in vitro, and 94.54% against S. aureus biofilm in vivo. Bi2S3@Ag3PO4/Ti also shows good cell viability compared to pure Ti. This NIR-activated-inorganic hybrid semiconductor heterojunction coating is biocompatible and could be employed to eliminate biofilm effectively, which makes it a very promising strategy for the surface modification of bone implant materials.
关键词： Bi2S3@Ag3PO4 nanorod arrays,biofilm elimination,bone implants,near-infrared photocatalysts,heterostructures
更新于2025-09-11 14:15:04
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Microcontact Printing with Laser Direct Writing Carbonization for Facile Fabrication of Carbon‐Based Ultrathin Disk Arrays and Ordered Holey Films
摘要： A nanometer-thick carbon film with a highly ordered pattern structure is very useful in a variety of applications. However, its large-scale, high-throughput, and low-cost fabrication is still a great challenge. Herein, microcontact printing (μCP) and direct laser writing carbonization (DLWc) are combined to develop a novel method that enables ease of fabrication of nanometer-thick and regularly patterned carbon disk arrays (CDAs) and holey carbon films (HCFs) from a pyromellitic dianhydride-oxydianiline-based polyamic acid (PAA) solution. The effect of PAA concentration and pillar lattice structure of the polydimethyl siloxane stamp are systematically studied for their influence on the geometrical parameter, surface morphology, and chemical structure of the finally achieved CDAs and HCFs. Within the PAA concentration being investigated, the averaged thickness of CDAs and HCFs can be tailored in a range from a few tens to a few hundred of nanometers. The μCP+DLWc-enabled electrically conductive CDAs and HCFs possess the characteristics of ease-of-fabrication, nanometer-thickness, highly regular and controlled patterns and structures, and the ability to form on both hard and soft substrates, which imparts usefulness in electronics, photonics, energy storage, catalysis, tissue engineering, as well as physical, chemical, and bio-sensing applications.
关键词： direct laser writing carbonization,holey carbon films,microcontact printing,carbon disk arrays
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Development and investigation of linear Fresnel lens for concentrator space solar arrays
摘要： Highly efficient ultra-lightweight doubled linear Fresnel-lens concentrators of solar light, which operate in tandem with multijunction InGaP/GaAs/Ge solar cells, have been developed and fabricated. The concentrators have a total photoactive area of (50 × 100) mm2, with the total thickness of ≤0.35 mm and optical focus of 32 mm. The Fresnel profile of each linear lens in the concentrator is formed from silicone rubber on ≤ 100 μm radiation-hard glass. The efficiency of the linear lens concentrators was 90% for the AM0 spectrum (1367 W/m2). The efficiency of the concentrators was examined before and after the irradiation and thermal-cycling tests. A 10% decrease in the efficiency of the linear lens concentrators is observed upon irradiation with 1 MeV electrons at a fluence of 3×1015 cm-2 and a <10% decrease upon thermal-cycling after the radiation treatment. The optical efficiency of the linear lens concentrators decreased by 13% after crush-testing with the total damage area being 2.5%.
关键词： solar concentrator,space solar arrays,Fresnel lens,radiation hardness,thermal cycling
更新于2025-09-11 14:15:04
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Optimized arrangement of vertical cavity surface emitting laser arrays to improve thermal characteristics
摘要： An optimization method for an arrangement of vertical cavity surface emitting laser (VCSEL) arrays to improve thermal characteristics of the arrays is presented. The method is based on the principle of minimum potential energy and is implemented by a self-organizing algorithm. The thermal and electrical properties of the active regions of the unoptimized and optimized arrays were obtained by a self-consistent thermoelectric simulation of the VCSEL structure based on the finite element method. The output characteristics of the unoptimized and optimized 4 × 4 square VCSEL arrays were studied theoretically and practically. The results showed that the optimized arrays have improved thermal characteristics.
关键词： VCSEL arrays,optimization method,thermal characteristics,self-organizing algorithm,finite element method
更新于2025-09-11 14:15:04