Energy-efficient Light Sources Research Articles

МЕТАЛОГАЛОГЕННІ ЛАМПИ: ДОСЯГНУТИЙ РІВЕНЬ ТА ШЛЯХИ ПОДАЛЬШОГО ПІДВИЩЕННЯ СВІТЛОВОЇ ЕФЕКТИВНОСТІ ЕНЕРГОЕКОНОМІЧНИХ ДЖЕРЕЛ СВІТЛА

В роботі аналізуються сучасні конструкції та параметри комерційних зразків металогалогенних ламп провідних світових виробників, їх переваги та недоліки перед іншими енергоекономічними джерелами світла та проведено аналіз можливих шляхів подальшого підвищення світлових параметрів цих ламп.

Advancement in Road Lighting

Road lighting is on the verge of one of the most attentive changes since its first introduction. The synergetic effect of the advancement of road lighting technology and usage pattern is going to change the concept of road lighting. By most estimates, light emitting diodes (LEDs) are the most energy efficient light sources that can be used in road lighting. Today, the energy saving potential when replacing HPS lamps with LED luminaires is one-third with current technology and two-thirds with improved technology in the future. This technological transformation has the potential of energy saving up to 83 % in comparison with HPS lamps. The energy saving is achievable with changing the pattern of use by intelligent road lighting control based on reducing burning hours. Intelligent road lighting can be based on such parameters as traffic density, ambient light, road condition and weather circumstances. It can also be more dynamic and consider the combined effect of road lighting and individual car headlights. The widespread adaptation of these emerging technologies is envisioned to lead towards more sustainable lighting.

Broadly Tunable Self-injection Locked InAs/InP Quantum-dash Laser Based Fiber/FSO/Hybrid Fiber-FSO Communication at 1610 nm

We report a self-injection-locked InAs/InP quantum-dash tunable laser with ∼11 nm (∼1602–1613 nm) tuning window for next generation multiuser ultrahigh capacity fiber/free-space optics (FSO)/hybrid fiber-FSO-based optical networks. A tunability of >18 independently locked subcarriers with ∼28 dB side mode suppression ratio (SMSR) and stable (±0.1 dBm) mode power is exhibited, and an estimated small injection ratio of ∼–22 dBm is found to sustain locking and SMSR. Error free transmission of 100 and 128 Gb/s externally modulated dual-polarization quadrature phase shift keying (DP-QPSK) signals over 20 km single mode fiber (SMF) and 16 m indoor FSO links are demonstrated across 8 and 4 individual subcarriers, respectively, thus covering the entire tuning range. Moreover, up to 168 (192) Gb/s successful transmission over 10 km SMF (BTB) and 176 Gb/s over 16 m FSO link is achieved on a ∼1610 nm subcarrier. Finally, a 128 Gb/s DP-QPSK transmission over 11 km SMF–8 m FSO–11 km SMF hybrid system is accomplished, thus paving the potential deployment of this single-chip, cost-effective, and energy efficient tunable light source in terabits/s next-generation passive optical networks.

Enhanced growth rate and ulvan yield of Ulva pertusa using light-emitting diodes (LEDs)

Light-emitting diode (LED) technology offers potential energy-efficient light sources for algal aquaculture. In this study, the growth rate and ulvan yield of Ulva pertusa used for broad commercial applications were enhanced in vitro. To investigate the response of Ulva to LEDs, algae were grown under white fluorescent, pure primary color LED, and mixed LED lights for 28 days. Ulva sp. under blue LED and white fluorescent light showed higher specific growth rate (SGR, 12% day−1) than other light sources, while the growth under mixed red-blue LED light was lower than that under white fluorescent lighting. Despite the differences in alga growth under LEDs and white fluorescent light, few differences are observed in N and P content among algae grown under any light source. U. pertusa showed tissue nitrogen and ulvan contents in the ranges of 4.4–6.7% and 20.4–25.1%, respectively, under all LED light treatments. The ulvan extracted from algae under blue LED showed high levels of antioxidant activity measured with 2,2-diphenylpicrylhydrazyl (DPPH) radical and hydrogen peroxide. Moreover, the ulvan obtained under different lights showed different monosaccharide compositions. Based on these results, LEDs should be considered as the main light sources for indoor seaweed cultivation.

Influence of blue/red vs. white LED light treatments on biomass, shoot morphology, and quality parameters of hydroponically grown kale

Abstract Solid-state light emitting diodes (LEDs) are emerging as an energy efficient alternative lighting source in controlled environments. The objective of this study was to examine the impact of sole-source LED lighting quality/duration on biomass, morphology, and nutritional quality of kale (Brassica oleracea var. acephala) in a controlled environment. ‘Premier’ kale seedlings were grown hydroponically using a 30 d production cycle. Experimental LED treatments included: 1) white LED for 37 d; 2) 5% B/95% R for 37 d; 3) 20%B/80%R for 30 d; 4) 20%B/80%R for 25 d; 5) 20%B/80%R for 20 d; and 6) 20%B/80%R for 15 d prior to harvest. Treatments were arranged in a randomized complete block design, and three complete experimental runs were conducted. Plant height (cm), leaf length and width (cm), shoot and root fresh mass (g) and dry mass (g) were collected at harvest. Kale shoot tissues were measured for nutritionally important pigments, glucosinolates, mineral elements, and soluble carbohydrates. All plants treated with 20%B/80%R lighting were shorter compared to the white (37 d) and 5%B/95%R (37 d) treatments, respectively. Chlorophyll fluorescence parameters were influenced by LED treatment, while maximum quantum yield (QYmax) was not. LED light treatment impacted kale zeaxanthin (P = 0.01), antheraxanthin (P = 0.01), fructose (P = 0.03), and potassium (P = 0.02). Data suggest that increasing blue light during production has limited impact on 37-d old hydroponic kale developmental and nutritional parameters over continuous white LED lighting.

A quantum optical study of thresholdless lasing features in high-\u03b2 nitride nanobeam cavities

Exploring the limits of spontaneous emission coupling is not only one of the central goals in the development of nanolasers, it is also highly relevant regarding future large-scale photonic integration requiring energy-efficient coherent light sources with a small footprint. Recent studies in this field have triggered a vivid debate on how to prove and interpret lasing in the high-β regime. We investigate close-to-ideal spontaneous emission coupling in GaN nanobeam lasers grown on silicon. Such nanobeam cavities allow for efficient funneling of spontaneous emission from the quantum well gain material into the laser mode. By performing a comprehensive optical and quantum-optical characterization, supported by microscopic modeling of the nanolasers, we identify high-β lasing at room temperature and show a lasing transition in the absence of a threshold nonlinearity at 156 K. This peculiar characteristic is explained in terms of a temperature and excitation power-dependent interplay between zero-dimensional and two-dimensional gain contributions.

Analysis Criteria for Choosing Energy Efficient High-Quality Light Sources and Luminaires

The article analyses critera applying to the choice of energy efficient high quality light sources and luminaires, which are used in Russian domestic and international practice. It is found that national standards GOST P 54993–2012 and GOST P 54992– 2012 contain outdated criteria for determining indices and classes of energy efficiency of light sources and luminaires. They are taken from the 1998 EU Directive #98/11/EU “Electric lamps”, in which LED light sources and discharge lamps of high intensity were not included. A new Regulation of the European Union #874/2012/EU on energy labelling of electric lamps and luminaires, in which these light sources are taken into consideration, contains a new technique of determining classes of energy efficiency and new, higher classes are added. The article has carried out a comparison of calculations of the energy efficiency classes in accordance with GOST P 54993 and with Regulation #874/2012/EU, and it is found out that a calculation using GOST P 54993 gives underrated energy efficiency classes. This can lead to interdiction of export for certain light sources and luminaires, can discredit Russian domestic manufacturer light sources and does not correspond to the rules of the World Trade Organization (WTO).

Continuous-wave operation in directly patterned perovskite distributed feedback light source at room temperature.

We report a directly patterned perovskite distributed feedback (DFB) resonator and show narrow amplified spontaneous emission (ASE) at pump powers as low as 0.1 W/cm2 under continuous-wave (CW) optical pumping conditions at room temperature. Compared to the pristine thin film photoluminescence spectrum, a 16-fold reduction in emission linewidth in the MAPbI3 DFB cavity was observed. The direct nanostructuring of perovskites was achieved by thermal nanoimprint lithography. Our findings pave the way toward realizing CW pumped perovskite lasers at room temperature and energy-efficient perovskite light sources.

Cone and melanopsin contributions to human brightness estimation.

We determined the contributions of cone and melanopsin luminance signaling to human brightness perception. The absolute brightness of four narrowband primary lights presented in a full-field Ganzfeld was estimated in two conditions, either cone luminance-equated (186.7-1,867.0 cd·m-2) or melanopsin luminance-equated (31.6-316.3 melanopsin cd·m-2). We show that brightness estimations for each primary light follow an approximately linear increase with increasing cone or melanopsin luminance (in log units), but are not equivalent for primary lights equated with either cone or melanopsin luminance. Instead, brightness estimations result from a combined interaction between cone and melanopsin signaling. Analytical modeling with wavelength-dependent coefficients signifies that melanopsin luminance positively correlates with brightness magnitudes, and the cone luminance has two contribution components, one that is additive to melanopsin luminance and a second that is negative, implying an adaptation process. These results provide a new framework for evaluating the physiological basis of brightness perception and have direct practical applications for the development of energy-efficient light sources.

Hospital Lighting System Using Energy Efficient Light Sources

Lighting in hospital facilities should support the visual performance of hospital workers such as doctors and nurses who need to examine and observe patients, dispense medication, perform as per clinical procedures, and view displays and papers clearly. Proper Light effect and colour should also provide comfortable, pleasant and natural visual environment for patients in healthcare facilities and their families, and support natural rhythms of sleeping and wakefulness. All the while the maintenance costs and energy use of hospital lighting should be minimized. For that, use of LED based lighting system using smart lighting technology is more valuable to provide desired illuminance value and uniformity as per the standards depending on the situation throughout the day. The objective of the journal paper is to study and design implementation of modern energy efficient lighting technology in hospital using smart lighting system depending on the situation throughout the day. Also, aim is to provide desired illuminance value and uniformity as per the standards. The new intelligent lighting control system should be designed to maximize the utilization of daylight with energy efficient light source.

Critical review on life cycle inventories and environmental assessments of LED-lamps

ABSTRACTResource scarcity, hazardous waste, and climate change are the driving forces for developing energy efficient and low-toxic lighting sources. Currently, solid state lighting based on light-emitting diodes is expected to become the most dominant lighting technology of the future, mostly driven by its advantage with respect to energy efficiency. Parallel to the ongoing development of light-emitting diode-based lighting sources, a number of single case and comparative life cycle assessment studies of LED-lamps and components in varying study settings were carried out. However, these studies mostly rely to specific lamp designs, which limits general conclusions. This work includes a summary of the global market of lighting and LED-lamp technologies, followed by a comprehensive review and comparison of published life cycle assessment studies. In addition, we take also some aspects, which are relevant for the well-being of an end-user and which are usually not treated in life cycle assessment studies, like glare and health issues, into consideration. A critical interpretation of the assumptions and outcomes of these studies is given and questions that remain unsettled and therefore should be addressed in future studies are discussed.

Telecom-Wavelength Bottom-up Nanobeam Lasers on Silicon-on-Insulator.

Semiconductor nanowire lasers are considered promising ultracompact and energy-efficient light sources in the field of nanophotonics. Although the integration of nanowire lasers onto silicon photonic platforms is an innovative path toward chip-scale optical communications and photonic integrated circuits, operating nanowire lasers at telecom-wavelengths remains challenging. Here, we report on InGaAs nanowire array lasers on a silicon-on-insulator platform operating up to 1440 nm at room temperature. Bottom-up photonic crystal nanobeam cavities are formed by growing nanowires as ordered arrays using selective-area epitaxy, and single-mode lasing by optical pumping is demonstrated. We also show that arrays of nanobeam lasers with individually tunable wavelengths can be integrated on a single chip by the simple adjustment of the lithographically defined growth pattern. These results exemplify a practical approach toward nanowire lasers for silicon photonics.

Electronic Scattering of Graphene Plasmons in the Terahertz Nonlinear Regime

Graphene possesses large Kerr nonlinearities that enabled the realization of energy-efficient nonlinear optical devices. At the same time, electronic scattering of graphene plasmons shows very high energy transfer efficiencies at very low beam energies due to its extremely large plasmon wave vector. We have tapped into these two unique optical properties of graphene to study the potential of an energy-efficient optoelectronic light source and all-optical modulator. We found that 2π-phase shift and 94% loss modulation is achievable with just a 25.6-V electron beam passing 10 nm above a graphene waveguide with a Fermi level of 0.1 eV. This also enables nonlinear optical devices to utilize in situ generated plasmons without the need of external optics, which could herald the return of vacuum nanoelectronics.

Special features of radio control link for energy efficient LED light sources

The aim of the study is to reveal the special features of radio control link model in LR-WPAN under operating conditions of interference of the reflected and the line-of-sight component and to evaluate the radio link's range of positive light source control. The results of development and practical implementation of controlled spectrally tunable light emitting diode (LED) light sources with ISM- and ZigBee (IEEE 802.15.04)-based radio frequency transceivers are presented. A software application developed in LabVIEW simulation of a radio control link for light sources and used for evaluating the radio control link's range of various combinations of polarization of transmitting and receiving antennas has been discussed. It was established and experimentally verified that the received energy was able to be computed using the two-ray model: a line-of-sight ray and the reflected one. This approach is simpler as compared to cellular networks in which multiple reflections from various objects result in multi-path propagation without line-of-sight component.

Improving the nonlinear energy conversion efficiency of a Kerr-comb-based broadband multi-wavelength light source by introducing an optical feedback loop

We simulate the generation of microcavity solitons in Kerr combs, evaluate their characteristics in the frequency domain via the Lugiato–Lefever equation (LLE), and optimize their shapes in the time domain by changing some related parameters to flatten the spectrum of the optical frequency combs and improve the nonlinear energy conversion efficiency of the underlying four-wave mixing process. In addition, we propose a new Kerr comb generation scheme to obtain an energy-efficient multi-wavelength light source by introducing an optical feedback loop with phase control in the pumping system. The simulation results show that the proposed scheme can enhance the nonlinear energy conversion efficiency of the multi-wavelength source and reduce the pump power level by about 32%.

Three-Dimensional TiO2 Structures Incorporated with Tungsten Oxide for Treatment of Toxic Aromatic Volatile Compounds

This study assessed 3D WO3–TiO2 nanoflowers (WTNF) synthesized by a combined hydrothermal–ultrasonication–impregnation method for their applicability to the treatment of aromatic volatile compounds under visible-light illumination. The scanning electron microscopy exhibited the formation of 3D structures in the prepared WTNF samples. The X-ray diffraction patterns and energy dispersive X-ray results indicated a successful incorporation of WO3 into TNF structures. The UV-visible spectroscopy showed that the prepared WTNF samples can be functioned under visible light irradiation. The output-to-input concentration ratios of toluene and o-xylene with WTNF samples were lower than those of TiO2 nanoflowers. These findings were illustrated on the basis of charge separation ability, adsorption capability, and light absorption of the sample photocatalysts. The input-to-output concentration ratios of the target chemicals were lowest for 10 M NaOH and highest for 5 M NaOH. The photocatalytic degradation efficiencies of WTNF sample photocatalysts increased with increasing WO3 content from 0.1% to 1.0%, and dropped gradually with increasing WO3 content further to 4.0%. Light-emitting-diodes (LEDs) are a more highly energy-efficient light source compared to a conventional lamp for the photocatalytic degradation of toluene and o-xylene, although the photocatalytic activity is higher for the conventional lamp.

Review of organic light-emitting diodes with thermally activated delayed fluorescence emitters for energy-efficient sustainable light sources and displays

Thermally activated delayed fluorescence (TADF) is an emerging hot topic. Even though this photophysical mechanism itself has been described more than 50 years ago and optoelectronic devices with organic matter have been studied, improved, and even commercialized for decades now, the realization of the potential of TADF organic light-emitting diodes (OLEDs) happened only recently. TADF has been proven to be an attractive and very efficient alternative for phosphorescent materials, such as dopants in OLEDs, light-emitting electrochemical cells as well as potent emitters for chemiluminescence. In this review, the TADF concept is introduced in terms that are also understandable for nonchemists. The basic concepts behind this mechanism as well as state-of-the-art examples are discussed. In addition, the future economic impact, especially for the lighting and display market, is addressed here. We conclude that TADF materials are especially helpful to realize efficient, durable deep blue and white displays.

THE EFFECT OF ENERGY-EFFICIENT LIGHT SOURCES ON THE QUALITY OF ELECTRICITY

The paper analyzes the range of current from energy-efficient light sources (LSs), such as compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs). The studied LSs exceed the standard values for the current harmonics, even with passive power factor correction. We have developed a methodology for calculating relative errors of active energy meters that measure the energy used by CFLs and LEDs and applied the methodology to determine the values of the relative errors of the induction and the digital meters. It is found that the errors of of both types of electricity meters for measuring power in the circuits with the tested LSs–CFLs and LEDs–exceed the maximum permissible errors by 3.0 % and 4.0 % respectively. Thus, when the load is a source of non-sinusoidal current, a consumer is overcharged for electricity. The values of errors in electricity metering can be reduced by eliminating the causes of the deteriorating quality of electricity, i.e. by supplying the lighting installations with energy-efficient light sources provided with active power factor correction.

Changing to Energy Efficient Light Sources – An Analysis of the Energy Balance of Buildings

New light sources such as LED lamps have the potential to reduce the electricity for lighting significantly. However, by reducing the electricity for lighting, the building heating demand is increased. The effects on the building energy balance of changing to more efficient light sources has been investigated by dynamic thermal modelling of typical Swedish single-family and multi-family residential houses. The results show savings on an average of 3.5 kWh/m2 and 0.62 €/m2 for single-family houses, and 3.4 kWh/m2 and 0.61 €/m2 for apartments in multi-family houses annually when changing from incandescent and halogen lamps to LED lamps.

Thin polymeric film microstructure manipulation for diffused reflectance applications

The need to reduce energy consumption in buildings has led to the widespread adoption of energy efficient light sources, such as LEDs. Diffused light reflectors are usually preferred to distribute LED illumination uniformly across the room. In this study, unpigmented PMMA films were studied for their diffused reflectance properties. PMMA films were cast onto a cold plate under varied humidity conditions to promote the formation of a porous microstructure via solid/liquid/liquid phase separation. The relationship between casting conditions, nonsolvent content, microstructure, and diffused reflectance was studied. The diffused reflectance was evaluated using a UV/Vis spectrophotometer with an integration sphere, and the microstructure was evaluated with an SEM. It was found that increasing the nonsolvent concentration either through increased absorption of ambient humidity or by directly incorporating water into the recipe creates pores that efficiently refract visible light. Reflectance in the mid 80% was obtained just by exploiting the difference in refractive index between the PMMA and the air‐filled pores. High diffused reflectance has been achieved in PMMA films purely by manipulating the film's microstructure without the use of other expensive polymers or pigments. POLYM. ENG. SCI., 55:2878–2883, 2015. © 2015 Society of Plastics Engineers