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Synthetic Bessel light needle for extended depth-of-field microscopy
摘要： An ultra-long light needle is highly desired in optical microscopy for its ability to improve the lateral resolution over a large depth of field (DOF). However, its use in image acquisition usually relies on mechanical raster scanning, which compromises between imaging speed and stability and thereby restricts imaging performance. Here, we propose a synthetic Bessel light needle (SBLN) that can be generated and scanned digitally by complex field modulation using a digital micromirror device. In particular, the SBLN achieves a 45-fold improvement in DOF over its counterpart Gaussian focus. Further, we apply the SBLN to perform motionless two-dimensional and three-dimensional microscopic imaging, achieving both improved resolution and extended DOF. Our work is expected to open up opportunities for potential biomedical applications.
关键词： depth-of-field microscopy,motionless imaging,Bessel light needle,digital micromirror device
更新于2025-09-23 15:21:21
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Analog Radio-over-fiber WDM-PON Architecture for 5G Millimeter-wave Interface
摘要： As the standardization of network-assisted device-to-device (D2D) communications by the Third Generation Partnership Project progresses, the research community has started to explore the technology potential of new advanced features that will largely impact the performance of 5G networks. For 5G, D2D is becoming an integrative term of emerging technologies that take an advantage of the proximity of communicating entities in licensed and unlicensed spectra. The European 5G research project Mobile and Wireless Communication Enablers for the 2020 Information Society (METIS) has identified advanced D2D as a key enabler for a variety of 5G services, including cellular coverage extension, social proximity, and communicating vehicles. In this paper, we review the METIS D2D technology components in three key areas of proximal communications—network-assisted multi-hop, full-duplex, and multi-antenna D2D communications—and argue that the advantages of properly combining cellular and ad hoc technologies help to meet the challenges of the information society beyond 2020.
关键词： vehicular communications,MIMO systems,full duplex,Device-to-device communications,network coding,cooperative communications
更新于2025-09-23 15:21:01
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[IEEE 2020 12th International Conference on Measuring Technology and Mechatronics Automation (ICMTMA) - Phuket, Thailand (2020.2.28-2020.2.29)] 2020 12th International Conference on Measuring Technology and Mechatronics Automation (ICMTMA) - Review on PD Ultrasonic Detection Using EFPI - Part I: the Optical Fiber Sensing Technologies
摘要： We report the development of multistrata subsurface laser-modified microstructure with backgrind-assisted controlled fracture for defect-free ultrathin die fabrication. This study focuses on the microstructural properties and formation mechanisms of the subsurface Si dislocation belt layer with respect to laser scanning speed, pulse laser energies, and interstrata distances. We optimize and exploit the multistrata interactions between generated thermal shock waves and the preceding dislocation belt layers formed to initiate frontal crack fractures that separate out the individual dies from within the interior of the wafer. A new partial-SD before grinding (p-SDBG) integration scheme based upon the tandem use of three-strata SD for controlled crack fracture toward the frontside of the wafer followed by static loading from backgrinding to complete full kerf separation is demonstrated. The optimized three-strata SD process and p-SDBG integration scheme can be used to compensate for the high backside reflectance wafers to produce defect-free eight die stacks of 25-μm-thick mechanically and 46-μm-thick electrically functional 2-D NAND memory dies.
关键词： laser,semiconductor device packaging,semiconductor memory,Defects,wafer dicing,semiconductor device manufacture
更新于2025-09-23 15:21:01
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Resource and Power Allocation in SWIPT Enabled Device-to-Device Communications Based on a Non-Linear Energy Harvesting Model
摘要： Due to the limited battery capacity in mobile devices, simultaneous wireless information and power transfer (SWIPT) has been proposed as a promising solution to improving the energy efficiency (EE) in Internet of things (IoT) networks, i.e., device-to-device (D2D) networks, by allowing mobile devices to harvest energy from ambient radio frequency (RF) signals. However, the non-linear behavior of RF energy harvesters has largely been ignored in existing works on SWIPT. In this paper, we propose to maximize the sum EE of all D2D links in a D2D underlaid cellular network by optimizing the resource and power allocation based on a non-linear energy harvesting (EH) model. Toward this end, we first propose a pre-matching algorithm to divide the D2D links into a SWIPT enabled group and a non-EH group that cannot meet the EH circuit sensitivity. We then develop a two-layer iterative algorithm to jointly optimize the D2D transmission power and the power splitting ratio to maximize the EE for each SWIPT enabled D2D link. On this basis, we build the preference lists for both SWIPT enabled D2D links and cellular user equipment (CUEs), and propose a one-to-one constraint stable matching algorithm to maximize the sum EE of all SWIPT enabled D2D links by optimizing the spectrum resource sharing between D2D links and CUEs. The sum EE of non-EH D2D links is maximized through an iterative power control algorithm and a one-to-one stable matching algorithm. Simulation results show that our proposed algorithms achieve a much higher sum EE than the existing matching based energy-efficient resource allocation scheme for SWIPT enabled D2D networks.
关键词： Device-to-device,underlay,energy harvesting,power control,resource allocation,SWIPT,energy efficiency,matching theory
更新于2025-09-23 15:21:01
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Photovoltaic anodes for enhanced thermionic energy conversion
摘要： Thermionic energy converters are heat engines based on the direct emission of electrons from a hot cathode towards a colder anode. Since the thermionic emission is unavoidably accompanied by photonic emission, radiative energy transfer is a significant source of losses in these devices. In this letter, we provide the experimental demonstration of a hybrid thermionic-photovoltaic device that is able to produce electricity not only from the electrons, but also from the photons that are emitted by the cathode. Thermionic electrons are injected in the valence band of a gallium arsenide semiconducting anode, then pumped to the conduction band by the photovoltaic effect, and finally extracted from the conduction band to produce useful energy before they are re-injected in the cathode. We show that such a hybrid device produces a voltage boost of ~ 1V with respect to a reference thermionic device made of the same materials and operating under the same conditions. This proof of concept paves the way to the development of efficient thermionic and photovoltaic devices for the direct conversion of heat into electricity.
关键词： thermionic energy conversion,photovoltaic,hybrid device,voltage boost,gallium arsenide
更新于2025-09-23 15:21:01
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Development of Combinatorial Pulsed Laser Deposition for Expedited Device Optimization in CdTe/CdS Thin-Film Solar Cells
摘要： A combinatorial pulsed laser deposition system was developed by integrating a computer controlled scanning sample stage in order to rapidly screen processing conditions relevant to CdTe/CdS thin-film solar cells. Using this system, the thickness of the CdTe absorber layer is varied across a single sample from 1.5 ??m to 0.75 ??m. The effects of thickness on CdTe grain morphology, crystal orientation, and cell efficiency were investigated with respect to different postprocessing conditions. It is shown that the thinner CdTe layer of 0.75 ??m obtained the best power conversion efficiency up to 5.3%. The results of this work shows the importance that CdTe grain size/morphology relative to CdTe thickness has on device performance and quantitatively exhibits what those values should be to obtain efficient thin-film CdTe/CdS solar cells fabricated with pulsed laser deposition. Further development of this combinatorial approach could enable high-throughput exploration and optimization of CdTe/CdS solar cells.
关键词： combinatorial pulsed laser deposition,power conversion efficiency,grain morphology,CdTe/CdS thin-film solar cells,device optimization,crystal orientation
更新于2025-09-23 15:21:01
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Performance evaluation and optimization of the cooling system of a hybrid thermionic-photovoltaic converter
摘要： Hybrid thermionic-photovoltaic (TIPV) converters are efficient and clean solutions for the direct conversion of thermal energy to electricity, taking advantage of both the photovoltaic and thermionic phenomena. An important hurdle for their efficient operation is the overheating of the PV cell integrated within the TIPV anode, due to partial conversion of the emitted electron and photon fluxes to thermal heat. This obstacle needs to be overcome with an efficient, yet practical, cooler. In this work, a copper plate heat spreader is experimentally tested for TIPV cathode temperatures up to 1450 °C, whilst its performance is also assessed using a validated CFD model for temperatures up to ~2000 °C. A multi-parametric analysis is conducted testing two coolants: i) a water/ethylene glycol mixture at various temperatures (?5–40 °C) and mass flow rates (0.05–0.4 kg·s?1), and, ii) cryogenic liquid nitrogen at a temperature of ?196 °C and mass flow rate of 0.074 kg·s?1. Numerical results reveal that with water/ethylene mixture the PV can withstand heat fluxes up to 360 W·cm?2, without its temperature exceeding 100 °C. For higher thermal fluxes (360–600 W·cm?2), cryogenic liquid nitrogen is found to prevent the PV overheating and, therefore, is an attractive coolant; however, it poses safety concerns due to its possible boiling. Finally, two additional cooling system designs are proposed, a heat sink with straight fins and another with copper pipes, which offer higher heat transfer areas, but are more difficult to manufacture, than the copper plate heat spreader.
关键词： Ultra-high power density,Copper plate heat spreader,Cooling system design optimization,Electronic device,Computational fluid dynamics (CFD)
更新于2025-09-23 15:21:01
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Geometrical self-testing of partially entangled two-qubit states
摘要： Quantum nonlocality has recently been intensively studied in connection to device-independent quantum information processing, where the extremal points of the set of quantum correlations play a crucial role through self-testing. In most protocols, the proofs for self-testing rely on the maximal violation of the Bell inequalities, but there is another known proof based on the geometry of state vectors to self-test a maximally entangled state. We present a geometrical proof in the case of partially entangled states. We show that, when a set of correlators in the simplest Bell scenario satisfies a condition, the geometry of the state vectors is uniquely determined. The realization becomes self-testable when another unitary observable exists on the geometry. Applying this proven fact, we propose self-testing protocols by intentionally adding one more measurement. This geometrical scheme for self-testing is superior in that, by using this as a building block and repeatedly adding measurements, a realization with an arbitrary number of measurements can be self-tested. Besides the application, we also attempt to describe nonlocal correlations by guessing probabilities of distant measurement outcomes. In this description, the quantum set is also convex, and a large class of extremal points is identified by the uniqueness of the geometry.
关键词： device-independent quantum information processing,Bell inequality,quantum nonlocality,self-testing
更新于2025-09-23 15:21:01
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Systematic Modulation of Charge Transport in Molecular Device through Facile Control of Molecule-Electrode Coupling using Double Self-assembled Monolayers Nanowire Junction
摘要： We report a novel solid-state molecular device structure based on double self-assembled monolayers (D-SAMs) incorporated into the suspended nanowire architecture to form “Au | SAM-1 || SAM-2 | Au” junction. Using commercially available thiol molecules that are devoid of synthetical difficulty, we constructed Au | S-(CH2)6-Ferrocene || SAM-2 | Au junction, with various length and chemical structure of SAM-2 to tune the coupling between ferrocene conductive molecular orbital and electrode of the junction. Combining low noise and wide temperature range measurement, we demonstrated systematically modulated conduction depending on the length and chemical nature of SAM-2. Meanwhile, transport mechanism transition from tunneling to hopping, and the intermediate state accompanied by the current fluctuation due to the coexistence of the hopping and tunneling transport channels, were observed. Considering the versatility of this solid-state D-SAMs in modulating the electrode-molecule interface and electroactive groups, this strategy thus provides a novel facile strategy for tailorable nanoscale charge transport study and functional molecular devices.
关键词： charge transport,molecular device,nanowire junction,self-assembled monolayers,ferrocene
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Transmission Electron Microscopy Study of UV-ozone Cleaned Silicon Surfaces for Application in High Efficiency Photovoltaics
摘要： We report a 3-D-stackable 1S1R passive cross-point resistive random access memory (RRAM). The sneak (leakage) current challenge in the cross-point RRAM integration has been overcome utilizing a ?eld-assisted superlinear threshold selector. The selector offers high selectivity of >107, sharp switching slope of <5 mV/decade, ability to tune the threshold voltage, stable operation at 125 °C, and endurance of >1011. Furthermore, we demonstrate 1S1R integration in which the selector-subthreshold current is <10 pA while offering >102 memory ON/ OFF ratio and >106 selectivity during cycling. Combined with self-current-controlled RRAM, the 1S1R enables high-density and high-performance memory applications.
关键词： selectivity,cross-point memory,select device,resistive random access memory (RRAM),sneak path,1S1R
更新于2025-09-23 15:21:01