Co-doping red-emitting Sr2Si5N8:Eu2+ into yellow-emitting phosphor-packaging for enhancing the optical properties of the 8500 K remote-phosphor packaging wleds

In the last decades, WLEDs attract more and more consideration in both academic and industrial purposes because of its advantages such as fast response time, environment friendliness, small size, long lifetime, and high efficiency. In this research, by doping the red-emitting Sr2Si5N8:Eu2+ phosphor particles into yellow-emitting YAG:Ce phosphor-packaging, a new recommendation for enhancing the optical properties (color uniformity, color rendering index, and lumen output) of the 8500 K remote-phosphor packaging WLEDs is presented, investigated, and demonstrated. By using Mat Lab and Light Tools software based on Mie Theory, the obtained results show that the optical properties of the 8500 K remote-phosphor packaging WLEDs significantly depended on Sr2Si5N8:Eu2+ concentration. The results have provided a potential practical recommendation for manufacturing remote-phosphor W-LEDs.Web of Science1341034102

Efficient Pulse Width Modulation LED Headlight Driver

LED headlights can provide better luminescence and less power consumption when compared to traditional halogen headlights. The adoption of LEDs in automobiles has been slow as the technology is more expensive than halogen bulbs, more complex to integrate, and younger. As such, an efficient, simplistic, and easy to use illumination driver was developed to spur on the widespread adoption of LED use in automobile lighting. The circuit developed is capable of providing the necessary illumination for a fraction of the energy input required by traditional lighting

Visible Light Communications towards 5G

5G networks have to offer extremely high capacity for novel streaming applications. One of the most promising approaches is to embed large numbers of co-operating small cells into the macro-cell coverage area. Alternatively, optical wireless based technologies can be adopted as an alternative physical layer offering higher data rates. Visible light communications (VLC) is an emerging technology for future high capacity communication links (it has been accepted to 5GPP) in the visible range of the electromagnetic spectrum (~370–780 nm) utilizing light-emitting diodes (LEDs) simultaneously provide data transmission and room illumination. A major challenge in VLC is the LED modulation bandwidths, which are limited to a few MHz. However, myriad gigabit speed transmission links have already been demonstrated. Non line-of-sight (NLOS) optical wireless is resistant to blocking by people and obstacles and is capable of adapting its’ throughput according to the current channel state information. Concurrently, organic polymer LEDs (PLEDs) have become the focus of enormous attention for solid-state lighting applications due to their advantages over conventional white LEDs such as ultra-low costs, low heating temperature, mechanical flexibility and large photoactive areas when produced with wet processing methods. This paper discusses development of such VLC links with a view to implementing ubiquitous broadcasting networks featuring advanced modulation formats such as orthogonal frequency division multiplexing (OFDM) or carrier-less amplitude and phase modulation (CAP) in conjunction with equalization techniques. Finally, this paper will also summarize the results of the European project ICT COST IC1101 OPTICWISE (Optical Wireless Communications - An Emerging Technology) dealing VLC and OLEDs towards 5G networks

Accelerating the deployment of Solid State Lighting (SSL) in Europe

Solid State Lighting, in particular the use of LEDs and OLEDs for general lighting, is a promising technology with high growth potential in Europe. The path for the development of SSL in Europe is sketched out in the Green Paper on SSL of the European Commission. The current study supports the direction taken in the green paper towards deployment of SSL. This paper sketches the lighting consumptions and various applications of SSL, from fully-mature applications till the general lighting sector when mass adoption is expected from 2015, first in the retrofit market then in the new lighting fixtures and luminaires. It focuses on the strengths and weaknesses of the European market for SSL. Distinction can be made between the outdoor lighting sector, where LEDs are more present, and indoor lighting, where the growth rate is still low. The LED industry is rather fragmented. It is usually divided into five segments: materials, equipment, finished lamps and components, luminaires and systems, and finally lighting services and solutions. One of the vulnerability areas is the fact Europe is dependent from China for a variety of semiconductor materials, including various rare earth elements (REE), that are used in the production of LEDs. The European manufacturing base is strong in the downstream segments of the value chain close to the application (40%) but it is weaker in the upstream segments (LED packaging, chips, wafers). Product design and marketing and sales are managed in Europe whereas product manufacturing takes place in Asia. R&D takes place mainly in Japan, the US and Europe. Through patent cross-licensing however the research base becomes broader, including China, Taiwan and South Korea. Europe is suffering from fragmented funding. Asian countries have a high budget for R&D. LED commercialisation channels might face a reshuffle, in particular when the industry will be moving to lighting services. For LEDs to penetrate the market more, end-user information and training, as well as training for installers, would be necessary. LED is still a costly product, in particular in the general lighting segment where alternatives remain cheaper. The price needed for mass adoption has not yet been reached. It is estimated that a price of $8 would allow a 25% market share for LEDs. In Europe, a price of €10 would allow to reach, after some time, a 50% market share for LEDs versus 50% for CFLs in the residential sector. It is to be noted that the price for LED bulbs differs from one country to another, e.g. LED bulbs are cheaper in Japan than they are in the US or Europe. Despite the potential of SSL for energy efficiency and also better lighting, many obstacles to its development remain. Cost and consequently payback time are not yet in the advantage of LED-based general illumination, compared to conventional lighting technologies. Quality is an issue, particularly in the absence of standards, both for testing and for final products. Luminous efficacy and lifetime can still be improved. Last but not least, educational barriers remain, that could be overcome by training of all players in the market, from the designer to the user. As far as the environment is concerned, LEDs do not contain mercury. Life cycle analysis seems to be quite favourable for SSL but further research into environment and health benefits will be required to confirm this. Some of the obstacles to mass adoption in the general lighting segment will disappear as technology evolves to cheaper products with better light quality. But price and energy efficiency might not be the only selling elements for LEDs. Innovation might be an important asset when designing new lighting products. Further legislation and policy initiatives addressing SSL will need to be designed in such a way to reinforce Europe's strategic strengths in the lighting sector, as proposed in the Green paper on SSL of the European Commission.JRC.F.7-Renewable Energ

A New Vehicle Localization Scheme Based on Combined Optical Camera Communication and Photogrammetry

The demand for autonomous vehicles is increasing gradually owing to their enormous potential benefits. However, several challenges, such as vehicle localization, are involved in the development of autonomous vehicles. A simple and secure algorithm for vehicle positioning is proposed herein without massively modifying the existing transportation infrastructure. For vehicle localization, vehicles on the road are classified into two categories: host vehicles (HVs) are the ones used to estimate other vehicles' positions and forwarding vehicles (FVs) are the ones that move in front of the HVs. The FV transmits modulated data from the tail (or back) light, and the camera of the HV receives that signal using optical camera communication (OCC). In addition, the streetlight (SL) data are considered to ensure the position accuracy of the HV. Determining the HV position minimizes the relative position variation between the HV and FV. Using photogrammetry, the distance between FV or SL and the camera of the HV is calculated by measuring the occupied image area on the image sensor. Comparing the change in distance between HV and SLs with the change in distance between HV and FV, the positions of FVs are determined. The performance of the proposed technique is analyzed, and the results indicate a significant improvement in performance. The experimental distance measurement validated the feasibility of the proposed scheme

LED PROJECTS AND ECONOMIC TEST CASES IN EUROPE

This report presents the status of existing LED pilot actions in Europe, analysing 106 LED test cases from 17 European countries. Projects from the public and commercial sectors form the focus of the report. Reviewed test cases include the use of LED technology in various applications. The results of test cases demonstrate wide variation. Installations offer energy savings of 59% in average (savings range from 10% up to more than 90%), either compared to the original installation or to reference consumption. In many applications, LEDs are competitive, yet a large number of projects are still in the trial phase. In these cases, economic aspects are relatively less relevant, and are often not even accounted for. From the test cases reviewed, most successful applications, in terms of savings and economic considerations, are 1) replacement of incandescent light bulbs in traffic light systems, and 2) replacement of halogen spotlights in indoor applications. Main co-benefits of LED projects analysed include: low maintenance costs, improved lighting characteristics, good indoor and outdoor lighting quality, improved ambience and atmosphere, no UV radiation, environmental benefits and improved security. On the other hand, some challenges to address include: improve the quality characteristics of LEDs and the quality of information and data provided by manufacturers/suppliers, and optimality of LED technology for existing street lighting systems. In order to fully utilise the energy saving potential of LED technology, careful evaluation of existing projects and exchange of information on good practices is necessary. Exploration of bottlenecks and risks is also an important task. Quality characteristics of LEDs, and quality of data provided by manufacturers, will remain the main challenges to penetration of the technology.JRC.F.7-Renewable Energ

High-resolution headlamps – technology analysis and system design

High-resolution vehicle headlamps are the technological way to intelligently illuminate the traffic area to increase safety and comfort. For the technical realization of these headlamps, different technologies come into question, which are the subject of intensive research at universities and among the manufacturers. We present an overview of the possible technologies and analyze their potential for use in high-resolution headlamps. Furthermore, we explain how the design of the optical system for the different technologies can be made. Another part of this paper is the comparison of published prototypes of high-resolution headlamps and the compilation of key properties

Deep Learning Framework for Wireless Systems: Applications to Optical Wireless Communications

Optical wireless communication (OWC) is a promising technology for future wireless communications owing to its potentials for cost-effective network deployment and high data rate. There are several implementation issues in the OWC which have not been encountered in radio frequency wireless communications. First, practical OWC transmitters need an illumination control on color, intensity, and luminance, etc., which poses complicated modulation design challenges. Furthermore, signal-dependent properties of optical channels raise non-trivial challenges both in modulation and demodulation of the optical signals. To tackle such difficulties, deep learning (DL) technologies can be applied for optical wireless transceiver design. This article addresses recent efforts on DL-based OWC system designs. A DL framework for emerging image sensor communication is proposed and its feasibility is verified by simulation. Finally, technical challenges and implementation issues for the DL-based optical wireless technology are discussed.Comment: To appear in IEEE Communications Magazine, Special Issue on Applications of Artificial Intelligence in Wireless Communication

Modelling and characterization of Quantum Dots as QLED devices for automotive lighting systems

This work reports the design, manufacturing and numerical simulation approach of an electroluminescent quantum dot light emitting device (QLED) based on quantum dots as an active layer. In addition, the electrical I-V curve was measured, observing how the fabrication process and layer thickness have an influence in the shape of the plot. This experimental device enabled us to create a computational model for the QLED based on the Transfer Hamiltonian approach to calculate the current density J(mA/cm2), the band diagram of the system and the accumulated charge distribution. Thanks to the QLED simulator developed, it would be possible to model the device and anticipate the electrical performance in a theoretical design step before going to QLED manufacturing at the laboratory. Eventually, particular automotive lighting system demonstrators were designed to integrate the theoretical and experimental research carried out in an industrial automotive product.Tesis Univ. Granada