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Plasmonic Nanoparticle Film for Low-Power NIR-Enhanced Photocatalytic Reaction
摘要： Plasmonic metal nanostructures offer the unique ability to effectively enhance sunlight harvesting by localized surface plasmon resonance (LSPR), which can induce direct photocatalytic reactions. However, only metal nanoparticles with a relatively low magnitude of electromagnetic field enhancement usually require a high illumination intensity to ensure the catalytic performance, which greatly limits the solar photocatalytic efficiency. Herein, we designed plasmonic Au nanoparticle film with high electromagnetic field enhancement to achieve high-efficiency catalytic activity under low power NIR light illumination. This work minimized the influence of the photothermal effect on the reaction by using a low illumination intensity and further revealed the main contribution of plasmon-excited hot electrons to the photochemical reaction. This study provides important insights into the study of the mechanism of LSPR in photocatalytic reactions and further improves the efficiency of solar energy utilization.
关键词： Localized surface plasmon resonance,hot electrons,low power illumination,electromagnetic field enhancement,NIR photocatalysis
更新于2025-09-19 17:13:59
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Spectral-Efficiency -Illumination Pareto Front for Energy Harvesting Enabled VLC Systems
摘要： The continuous improvement in optical energy harvesting devices motivates the development of visible light communication systems that utilize such available free energy. In this paper, an outdoor visible light communications (VLC) system is considered where a VLC base station sends data to multiple users that are capable of harvesting optical energy. The proposed VLC system serves multiple users using time division multiple access (TDMA) with unequal time and power allocation, which are allocated to achieve the system communications and illumination objectives. In an outdoor setup, the system lighting objective is to maximize the average illumination flux, while the communication design objective is to maximize the spectral efficiency (SE). A multiobjective optimization problem is formulated to obtain the Pareto front of the SE-illumination region. To this end, the marginal optimization problems are solved first using low complexity algorithms. Then, based on the proposed algorithms, a Karush-Kuhn-Tucker-based algorithm is developed to obtain an inner bound of the Pareto front for the SE-illumination tradeoff. The inner bound for the Pareto-front is shown to be close to the optimal Pareto-frontier via several simulation scenarios for different system parameters.
关键词： Pareto front,outdoor communication,illumination,multiobjective optimization,mass gathering events,spectral efficiency,energy harvesting,Visible light communication
更新于2025-09-19 17:13:59
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Multi-wavelength fiber laser based on dual-Sagnac comb filter for LP11 modes output
摘要： In this study, we investigate the spectral distribution of the light scattered in step-index polymer optical ?bers by illuminating the ?bers transversely to their symmetry axis. For that purpose, we have performed wavelength-dependent scattering measurements over the spectral range 400–750 nm in three different commercial step-index polymer optical ?bers. We have estimated the mean size of the most in?uential scattering centers in these polymer optical ?bers, analyzing theoretically the experimental results obtained.
关键词： side-illumination,Polymer optical ?ber (POF),scattering
更新于2025-09-19 17:13:59
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Rapid and wide-range detection of NO <sub/>x</sub> gas by N-hyperdoped silicon with the assistance of a photovoltaic self-powered sensing mode
摘要： Wide dynamic range NOx sensors are vital for environment and health purposes, but few sensors could achieve wide range detection with ultralow and ultrahigh concentrations at the same time. In this article, the microstructured and nitrogen-hyperdoped silicon (N-Si) for NOx gas sensing is investigated systematically. Working by the change of surface conductivity, the sensor is ultra-sensitive to low concentration of NOx down to 11 ppb, and shows a rapid response/recovery time of 22/33 s for 80 ppb. When NOx concentration increases and exceeds a threshold value (10–50 ppm), an n–p conduction type transition is observed due to the inversion of the conduction type of major carriers, which limits the sensor’s dynamic range at high concentration. However, when the sensor works in a photovoltaic self-powered mode under the asymmetric light illumination (ALI), the limitation can be successfully overcome. Therefore, with the combination of the two working principles, a wide dynamic range stretching over six orders of magnitude (~0.011–4,000 ppm) can be achieved.
关键词： dynamic range,conduction type transition,asymmetric light illumination,hyperdoped silicon,self-powered gas sensing
更新于2025-09-19 17:13:59
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Transparent MoS <sub/>2</sub> /PEDOT Composite Counter Electrodes for Bifacial Dye-Sensitized Solar Cells
摘要： Dye-sensitized solar cells (DSSCs) are solar energy conversion devices with high efficiency and simple fabrication procedures. Developing transparent counter electrode (CE) materials for bifacial DSSCs can address the needs of window-transparent-type building-integrated photovoltaics (BIPVs). Herein, transparent organic?inorganic hybrid composite films of molybdenum disulfide and poly(3,4-ethylenedioxythiophene) (MoS2/PEDOT) are prepared to take full advantage of the conductivity and electrocatalytic ability of the two components. MoS2 is synthesized by hydrothermal method and spin-coated to form the MoS2 layer, and then PEDOT films are electrochemically polymerized on top of the MoS2 film to form the composite CEs. The DSSC with the optimized MoS2/PEDOT composite CE shows power conversion efficiency (PCE) of 7% under front illumination and 4.82% under back illumination. Compared with the DSSC made by the PEDOT CE and the Pt CE, the DSSC fabricated by the MoS2/PEDOT composite CE improves the PCE by 10.6% and 6.4% for front illumination, respectively. It proves that the transparent MoS2/PEDOT CE owes superior conductivity and catalytic properties, and it is an excellent candidate for bifacial DSSC in the application of BIPVs.
关键词： building-integrated photovoltaics,transparent counter electrode,MoS2/PEDOT composite,bifacial illumination,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Switching-off conventional lighting system and turning-on LED lamps in Kazakhstan: A techno-economic assessment
摘要： Growth of the global population is directly associated with the increase in energy consumption. This pattern can be predominantly seen in emerging economies. However, coping with economic growth while pledging to combat global warming is not a dilemma in the Republic of Kazakhstan, which launched in 2012 a strategy plan determined to have a 50% of its total energy demand supplied by renewables in 2050. A significant amount of energy consumption is generally attributed to lighting systems since developing countries are still utilizing non-efficient illuminants, including incandescent, tungsten halogen, and high-intensity discharge light bulbs. This paper presents the potential impact brought by switching current energy-intensive lighting technologies used in most of the territory of Kazakhstan to LED technology, scrutinizing three subsectors: residential, commercial/industrial and outdoor illumination, and considering the incentives of DAMU fund (available to develop green businesses) as well as realistic financial parameters. The study depicts a large margin of profit for the investors and resulted in an NPV equal to 412 bln, 81 bln, and 29.9 bln KZT for residential, commercial/industrial and outdoor sectors, respectively. The largest B–C ratio is found for outdoor facilities (21.8), followed by the residential sector (15.4) and the commercial sector (8.4).
关键词： LED,RETScreen,Energy efficiency,Illumination
更新于2025-09-19 17:13:59
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[IEEE ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Barcelona, Spain (2020.5.4-2020.5.8)] ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - The Effect of Power Allocation on Visible Light Communication Using Commercial Phosphor-Converted Led Lamp for Indirect Illumination
摘要： Visible light communication (VLC) systems should be designed to provide illumination and wireless data services simultaneously. To achieve this goal at a reasonable cost, the use of Phosphor-Converted (PC) LEDs for indirect illumination should be favored to provide a homogeneous and reliable coverage in the whole service area. Unfortunately, PC-LEDs found in the market so far have not been designed for data transmission; moreover, the response of the other (electro-)optical components of the VLC link are far from ideal. In this paper, we estimate the data rate that is feasible with VLC when indirect illumination is used. For this purpose, the end-to-end response of the VLC link is first modeled using actual measurements of the spectral power distribution of a PC-LED lamp and the ceiling reflectance. Then, different power allocation schemes are studied assuming an optical OFDM waveform. As commercial LEDs have a relatively slow time response, the equivalent VLC channel that results has strong frequency selectivity; therefore, notable data rate gains are achievable when water filling power allocation is applied.
关键词： Optical OFDM,Visible Light Communication,Illumination,Power Allocation,PC-LEDs
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) - Riga, Latvia (2019.10.7-2019.10.9)] 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) - Effects of PWM Dimming LED Illumination on Camera Images and Countermeasures
摘要： This paper presents the analysis of brightness fluctuation for camera images under the PWM dimming LED Illumination environment and countermeasures against it. The exposure dose of a camera, which depends on PWM frequency and duty, exposure time and shooting instant of a camera, and video frame rate, was analyzed using a computer simulation program. As a result, it was found that the brightness fluctuation did not occur in most cases when the PWM frequency of LED lighting was at a frequency of 24 kHz or its multiple. The experimental results confirmed the effectiveness of proposed brightness fluctuation prevention measures.
关键词： flicker,LED Illumination,PWM frequency,GaN HEMT,exposure time,camera
更新于2025-09-19 17:13:59
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[IEEE GLOBECOM 2019 - 2019 IEEE Global Communications Conference - Waikoloa, HI, USA (2019.12.9-2019.12.13)] 2019 IEEE Global Communications Conference (GLOBECOM) - Gated Recurrent Units Learning for Optimal Deployment of Visible Light Communications Enabled UAVs
摘要： In this paper, the problem of optimizing the deployment of unmanned aerial vehicles (UAVs) equipped with visible light communication (VLC) capabilities is studied. In the studied model, the UAVs can simultaneously provide communications and illumination to service ground users. Ambient illumination increases the interference over VLC links while reducing the illumination threshold of the UAVs. Therefore, it is necessary to consider the illumination distribution of the target area for UAV deployment optimization. This problem is formulated as an optimization problem whose goal is to minimize the total transmit power while meeting the illumination and communication requirements of users. To solve this problem, an algorithm based on the machine learning framework of gated recurrent units (GRUs) is proposed. Using GRUs, the UAVs can model the long-term historical illumination distribution and predict the future illumination distribution. In order to reduce the complexity of the prediction algorithm while accurately predicting the illumination distribution, a Gaussian mixture model (GMM) is used to fit the illumination distribution of the target area at each time slot. Based on the predicted illumination distribution, the optimization problem is proved to be a convex optimization problem that can be solved by using duality. Simulations using real data from the Earth observations group (EOG) at NOAA/NCEI show that the proposed approach can achieve up to 22.1% reduction in transmit power compared to a conventional optimal UAV deployment that does not consider the illumination distribution. The results also show that UAVs must hover at areas having strong illumination, thus providing useful guidelines on the deployment of VLC-enabled UAVs.
关键词： VLC,GMM,illumination distribution,GRU,optimization,UAV
更新于2025-09-19 17:13:59
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Polarization-Controlled Plasmonic Structured Illumination
摘要： Structured light in the subwavelength scale is important for a broad range of applications ranging from lithography to imaging. Of particular importance is the ability to dynamically shift the pattern of the fields, which has led to the development of structured illumination microscopy. Further extension of structured illumination to plasmonic systems has enabled imaging beyond diffraction limit. However, structured illumination usually requires complicated optical setups entailing moving mechanical parts. Here a polarization tunable structured plasmonic fields (SPF) is proposed and experimentally demonstrated. The SPF is formed by surface plasmon interference (SPI) generated by a fishbone-shaped metasurface on a thin gold film. Importantly, the SPF can be continuously shifted by merely varying the linear polarization state of an incident beam. The precise control of the fringes of structured illumination and elimination of mechanical control will have great potential in subdiffractional imaging for practical applications.
关键词： Plasmonic,metasurface,structured illumination,subdiffractional imaging
更新于2025-09-19 17:13:59