scholarly journals Grating Lobes in Higher-Order Correlation Functions of Arrays of Quantum Emitters: Directional Photon Bunching Versus Correlated Directions

Photonics ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 14 ◽  
Author(s):  
Iñigo Liberal ◽  
Iñigo Ederra ◽  
Richard Ziolkowski
Keyword(s):  
Correlation Function ◽  
Antenna Arrays ◽  
Quantum Interference ◽  
Light Emission ◽  
Optical Manipulation ◽  
Light Sources ◽  
The Impact ◽  
Directional Correlation Function ◽  
Identical Quantum ◽  
Quantum Emitters

Recent advances in nanofabrication and optical manipulation techniques are making it possible to build arrays of quantum emitters with accurate control over the locations of their individual elements. In analogy with classical antenna arrays, this poses new opportunities for tailoring quantum interference effects by designing the geometry of the array. Here, we investigate the N th -order directional correlation function of the photons emitted by an array of N initially-excited identical quantum emitters, addressing the impact of the appearance of grating lobes. Our analysis reveals that the absence of directivity in the first-order correlation function is contrasted by an enhanced directivity in the N th -order one. This suggests that the emitted light consists of a superposition of directionally entangled photon bunches. Moreover, the photon correlation landscape changes radically with the appearance of grating lobes. In fact, the photons no longer tend to be bunched along the same direction; rather, they are distributed in a set of correlated directions with equal probability. These results clarify basic aspects of light emission from ensembles of quantum emitters. Furthermore, they may find applications in the design of nonclassical light sources.

scholarly journals Impact of artificial illumination on the development of a leafmining moth in urban trees

2019 ◽  
Vol 21 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Sibylle Schroer ◽  
Eva Häffner ◽  
Franz Hölker
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Light Emission ◽  
Test Organism ◽  
Urban Trees ◽  
Continuous Illumination ◽  
Horse Chestnut ◽  
Light Sources ◽  
Strong Impact ◽  
The Impact

Light emission from street lighting or other light sources alters the living conditions for organisms in urban areas. Nowadays, the impact of light at night (ALAN) on urban plants and their trophic environment is not well understood. To gain more insight about herbivore plant’s interaction when exposed to ALAN, outdoor and greenhouse tests were conducted using the horse-chestnut leafminer, Cameraria ohridella, as a test organism due to its adaptive behavior. At the end of the season, the development of chestnut tree leaves and the leafminer were measured at illuminated versus non-illuminated sites in the city of Berlin and the rural area of Brandenburg. Illuminated leaves were larger than those grown in darker rural areas and, extended larval activity was recorded. Additionally, in the greenhouse, infested chestnut seedlings were exposed to two different light regimes; one treatment provided continuous illumination and the other short daylight conditions. After only one week, the mine size was lower on illuminated seedlings, presumably due to reduced leaf senescence. The leafminer developed a lower proportion of diapausing pupae and a higher proportion of free pupae, which leads to a further generation within the season. The results indicate a strong impact of ALAN on plant metabolism, a secondary effect on leafminer development and its larval activity. For urban trees, the consequence might be an increased herbivore / parasite pressure. For herbivores and parasites less adapted to winter damages than the invasive leafminer a reduced dormancy due to direct or indirect effects of ALAN could even threat the population.

THE IMPACT OF COLOURFUL AND DYNAMIC LED MEDIA FACADE AND BILLBOARDS ON ASTRONOMICAL OBSERVATIONS

2021 ◽  
Author(s):  
Steve Lau ◽  
Christopher Kyba ◽  
Richard J. Wainscoat
Keyword(s):  
Rayleigh Scattering ◽  
Light Emission ◽  
Wide Spectrum ◽  
Red Light ◽  
Light Sources ◽  
Shopping Malls ◽  
Astronomical Observations ◽  
White Leds ◽  
New Type ◽  
The Impact

More and more LED media façades and LED billboards are being installed on architecture and buildings in order to decorate city skylines or to deliver advertisements. The shopping malls in the busiest streets in city centers make extensive use of LEDs to attract tourists and to promote the nighttime economy and business. In order to achieve the desired graphic and the display needed, these LED media façades and LED billboards utilize RGB LEDs or RBG white LEDs and a control system which emits a wide spectrum of light, including blue, green and red light. Although each of these colors contributes to skyglow via Rayleigh scattering, bluer colors of light are more efficiently scattered, and are of particular concern. The shift of the usage of conventional light sources like incandescent lamp, low pressure sodium and high pressure sodium light sources to this new type of colorful and dynamic LED media façade and billboards has brought new challenges to astronomers. This paper describes how the light emission from LED media façades and LED billboards increases the artificial skyglow in the atmosphere and more importantly how this brightening skyglow affects astronomical observations.

Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions

2020 ◽  
Author(s):  
María Camarasa-Gómez ◽  
Daniel Hernangómez-Pérez ◽  
Michael S. Inkpen ◽  
Giacomo Lovat ◽  
E-Dean Fung ◽  
...  
Keyword(s):  
Single Molecule ◽  
Quantum Interference ◽  
Degrees Of Freedom ◽  
Building Blocks ◽  
Ferrocene Derivative ◽  
Single Molecule Junctions ◽  
Molecule Junction ◽  
Single Molecule Junction ◽  
The Impact ◽  
D Orbitals

Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted<br>some interest as functional elements of molecular-scale devices. Here we investigate the impact of<br>the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction<br>conductance. Measurements indicate that the conductance of the ferrocene derivative, which is<br>suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated<br>by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.<br>

VLSI Design for Functional Failure Analysis in the < 90 nm and Flip-Chip Era

2003 ◽  
Author(s):  
Yoav Weizman ◽  
Ezra Baruch
Keyword(s):  
Failure Analysis ◽  
Flip Chip ◽  
Light Emission ◽  
Vlsi Design ◽  
Optical Resolution ◽  
Critical Issue ◽  
Acquisition Time ◽  
Resolution Limit ◽  
Design Rules ◽  
The Impact

Abstract In recent years, two new techniques were introduced for flip chip debug; the Laser Voltage Probing (LVP) technique and Time Resolved Light Emission Microscopy (TRLEM). Both techniques utilize the silicon’s relative transparency to wavelengths longer than the band gap. This inherent wavelength limitation, together with the shrinking dimensions of modern CMOS devices, limit the capabilities of these tools. It is known that the optical resolution limits of the LVP and TRLEM techniques are bounded by the diffraction limit which is ~1um for both tools using standard optics. This limitation was reduced with the addition of immersion lens optics. Nevertheless, even with this improvement, shrinking transistor geometry is leading to increased acquisition time, and the overlapping effect between adjacent nodes remains a critical issue. The resolution limit is an order of magnitude above the device feature densities in the &lt; 90nm era. The scaling down of transistor geometry is leading to the inevitable consequence where more than 50% of the transistors in 90nm process have widths smaller than 0.4um. The acquisition time of such nodes becomes unreasonably long. In order to examine nodes in a dense logic cuicuit, cross talk and convolution effects between neighboring signals also need to be considered. In this paper we will demonstrate the impact that these effects may have on modern design. In order to maintain the debug capability, with the currently available analytical tools for future technologies, conceptual modification of the FA process is required. This process should start on the IC design board where the VLSI designer should be familiar with FA constraints, and thus apply features that will enable enhanced FA capabilities to the circuit in hand during the electrical design or during the physical design stages. The necessity for reliable failure analysis in real-time should dictate that the designer of advanced VLSI blocks incorporates failure analysis constraints among other design rules. The purpose of this research is to supply the scientific basis for the optimal incorporation of design rules for optical probing in the &lt; 90nm gate era. Circuit designers are usually familiar with the nodes in the design which are critical for debug, and the type of measurement (logic or DC level) they require. The designer should enable the measurement of these signals by applying certain circuit and physical constraints. The implementation of these constraints may be done at the cell level, the block level or during the integration. We will discuss the solutions, which should be considered in order to mitigate tool limitations, and also to enable their use for next generation processes.

scholarly journals Nanophosphors-Based White Light Sources

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1048 ◽  
Author(s):  
Maura Cesaria ◽  
Baldassare Di Bartolo
Keyword(s):  
Rare Earth ◽  
White Light ◽  
Volume Ratio ◽  
Light Sources ◽  
Co Doping ◽  
New Class ◽  
Luminescence Efficiency ◽  
Metal Doped ◽  
The Individual ◽  
The Impact

Miniaturization requests and progress in nanofabrication are prompting worldwide interest in nanophosphors as white-emission mercury-free lighting sources. By comparison with their bulk counterparts, nanophosphors exhibit reduced concentration quenching effects and a great potential to enhance luminescence efficiency and tunability. In this paper, the physics of the nanophoshors is overviewed with a focus on the impact of spatial confinement and surface-to-volume ratio on the luminescence issue, as well as rare earth-activated multicolor emission for white light (WL) output. In this respect, the prominently practiced strategies to achieve WL emission are single nanophosphors directly yielding WL by means of co-doping and superposition of the individual red, green, and blue emissions from different nanophosphors. Recently, a new class of efficient broadband WL emitting nanophosphors has been proposed, i.e., nominally un-doped rare earth free oxide (yttrium oxide, Y2O3) nanopowders and Cr transition metal-doped garnet nanocrystals. In regard to this unconventional WL emission, the main points are: it is strictly a nanoscale phenomenon, the presence of an emitting center may favor WL emission without being necessary for observing it, and, its inherent origin is still unknown. A comparison between such an unconventional WL emission and the existing literature is presented to point out its novelty and superior lighting performances.

scholarly journals Impact of Slope of Growing Trays on Productivity of Wheat Green Fodder by a Nutrient Film Technique System

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3009
Author(s):  
Andrius Grigas ◽  
Aurelija Kemzūraitė ◽  
Dainius Steponavičius ◽  
Aušra Steponavičienė ◽  
Rolandas Domeika
Keyword(s):  
Light Emitting Diode ◽  
Tap Water ◽  
Slope Angle ◽  
Experimental Studies ◽  
Matter Content ◽  
Light Sources ◽  
Dry Matter Content ◽  
Nutrient Film Technique ◽  
Indoor Lighting ◽  
The Impact

Application of hydroponic systems in feed production has not been extensively studied. Therefore, there is insufficient data on the effect of the slope of hydroponic growing trays used in the nutrient film technique on wheat fodder yield and its qualitative parameters. The slope of the trays has only been studied for food crops. This study conducted experimental research using a nutrient film technique hydroponic fodder growing device to evaluate the impact of growing tray slope angle on hydroponic wheat fodder production. The slope angle of the growing trays was changed from 2.0% (1.15°) to 8.0% (4.57°) with increments of 1.5% (0.86°). This research used two different light sources for wheat sprout illumination: indoor lighting (fluorescent lamps) and light-emitting diode illumination. In addition, two nutrient solutions were used for sprout irrigation: tap water and a solution enriched with macro- and microelements. Experimental studies confirmed the hypothesis that the slope angle of growing trays significantly affects the yield of wheat fodder grown for seven days. Analyzing the results, we found that the highest yield of wheat fodder after seven days of cultivation was achieved with growing trays sloped by 6.5% and using indoor lighting. In addition, we achieved the highest wheat fodder dry matter content using a 6.5% slope angle. Experimental studies also confirmed the hypothesis that using macro- and micronutrients in the nutrient solution does not significantly affect the yield of wheat fodder grown hydroponically for seven days.

scholarly journals METHOD OF CONTROLLING PRESENCE OF FOREIGN SUBSTANCES AND OBJECTS IN THE BORE OF THE BARREL USING MONOCHROME LIGHT

2021 ◽  
pp. 53-57
Author(s):  
V. Kozachuk ◽  
M. Sliusarenko
Keyword(s):  
Combustion Products ◽  
The Other ◽  
Light Sources ◽  
Current Value ◽  
Precision And Accuracy ◽  
Shell Particles ◽  
The Military ◽  
Parameter Values ◽  
The Impact ◽  
Powder Combustion

In the article, the authors propose a method for controlling the presence of foreign substances and objects inside the barrel. The problem of surface cleanliness control remains relevant in many areas, ranging from sanitary cleaning to nanoelectronics. In the military sphere, this becomes particularly important during the cleaning of cannon barrels. Both powder combustion products and cartridge cap and bullet shell particles are deposited in the barrel during firing from guns. Under the impact of high temperatures, the bullet particles are partially oxidized and cover the barrel channel with a thin layer of deposit of oxides, which are difficult to dissolve. As a result, the density of the bullet abuting the walls changes. This affects the characteristics of its motion inside the barrel. The accuracy of the shot is reduced, and subsequently the precision and accuracy of shooting in general decreases. The essence of the proposed method consists in the fact that a light source is placed in the bore of the barrel on one side, and an optical device is placed on the other side, with the help of which the presence of foreign substances and objects is monitored. Unlike the known methods, this method is characterized in that several monochrome light sources in addition are placed in turn in the bore of the barrel from the breech part, and in the bore of the barrel from the muzzle part there is equipment for receiving (detecting) monochrome light. Then, obtained monochrome light is analyzed, current value of its defined parameters is determined. At the next stage, parameter values of monochrome light fixed during control are compared with parameter values of reference signatures, which had been obtained before the barrel was put in service. These values are stored in equipment memory. If the values of at least one of the parameters from at least one of the monochrome light sources are found to be inconsistent with the parameters of the reference signatures, the equipment for receiving and analyzing monochrome light gives a signal about the presence of foreign substances and objects in the bore of the barrel.

AN OVERVIEW OF THE IMPACT OF STRAY LIGHT FROM COMMERCIAL GREENHOUSES

2021 ◽  
Author(s):  
K. Bertin ◽  
G. Zissis ◽  
G. Salas ◽  
P.M. Raynham ◽  
A. Moutsi ◽  
...  
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Stray Light ◽  
Significant Problem ◽  
Light Sources ◽  
Spectral Power Distribution ◽  
Outdoor Work ◽  
Local Residents ◽  
The Impact ◽  
Current Standards

Stray light from commercial greenhouses is becoming a significant problem causing disruption to wildlife activity and annoyance for local residents. To quantify the amount of stray light from a typical large greenhouse the authors have modelled several lighting installations based on a range of generic horticultural light sources. The impact of the stray light is dependent on the spectral power distribution of the sources employed, the intensity and distribution. Current standards for obtrusive light from outdoor work places do not seem to be suitable when applied to greenhouses.

The Effect of Light on Sleep and Sleep-Related Physiological Factors Among Patients in Healthcare Facilities: A Systematic Review

2019 ◽  
Vol 12 (4) ◽  
pp. 116-141
Author(s):  
Khatereh Hadi ◽  
Jennifer R. Du Bose ◽  
Young-Seon Choi
Keyword(s):  
Light Exposure ◽  
Bright Light ◽  
Light Sources ◽  
Related Factors ◽  
Healthcare Facilities ◽  
New Findings ◽  
Healthcare Environments ◽  
The Impact ◽  
Improve Patient ◽  
Bright Light Exposure

Objectives: Lighting is one of the environmental factors which can improve patient sleep in healthcare environments. Due to the high degree of variation in study designs and results on this topic, the implications have been difficult to interpret. This review consolidates studies on the impact of bright light exposure on sleep to identify lighting conditions that can be applied and researched in future healthcare environments. Methods: We searched for peer-reviewed articles on the impact of light on sleep or sleep-related outcomes in healthcare settings. We provided detailed analysis of the direct links between light and sleep, and a more cursory analysis of links between light and sleep-related factors, from 34 articles which met our inclusion criteria. Results: The current state of the literature includes evidence on how various durations and intensities of morning, midday, and evening bright light exposure, as well as whole-day light exposure interventions can improve specific aspects of sleep. Lighting interventions differed in all attributes (illuminance levels, exposure time, exposure duration, and spectral qualities) but showed promising results in improving patients’ sleep. Conclusions: Short-term bright light exposure in the morning, up to 2 hr of moderate (3,000–10,000 lux) morning exposures, up to 4 hr of moderate evening exposure, and whole-day exposures to lower illuminance levels (<3,000 lux) can improve patient sleep outcomes. Based on new findings on the mechanism through which light impacts sleep, future studies should be more specific about the spectral qualities of light sources.

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