Green Light Source Research Articles

Experimental characterization of peripheral photocurrent in CMOS photodiodes down to 65 nm technology

In this work, an in-depth experimental characterization of submicron CMOS p–n+ junction photodiodes operating under uniform illumination in the visible range is performed. The experimental measurements are used to validate a previous two-dimensional analytical model for the photoresponse estimation of these structures, which pays special attention to the lateral collection and was verified by means of device simulations. To do so, square p–n+ junction photodiodes with different sizes down to an active area of 0.56 μm wide have been fabricated in 180 and 65 nm technological nodes and characterized under blue, green and red light sources. As a result, the importance of the lateral collection in the overall response for small photodiodes that was previously theoretically reported is confirmed. The experimentally validated two-dimensional analytical model is a powerful tool that can be employed for the design of CMOS imagers and related electronics circuits.

Physiological response of sugar beet (Beta vulgaris) genotypes to a temporary water deficit, as evaluated with a multiparameter fluorescence sensor

Greenhouse and field experiments were carried out to evaluate the potential of specific fluorescence emission parameters for the detection of a temporary water deficit in selected sugar beet (Beta vulgaris L.) genotypes. Changes in the plant physiology due to reduced water availability were recorded with a multiparameter fluores- cence sensor in addition to destructive and non-invasive reference analysis. Our results show that an insufficient water supply is followed by only slight changes of the UV-excited blue fluorescence. However, significant alter- ations due to desiccation were detected in several chloro- phyll fluorescence parameters measured after excitation with UV, green and red light. In the scope of our activities, the relevance of the green light source for the fluorescence excitation became evident and enabled to characterize cultivar-specific reactions during dehydration and re-watering period. A field experiment was conducted to validate the data collected in the greenhouse. As proven, several days of low water supply led to effects similar to those observed in the greenhouse study. Our results indicate that the far-red fluorescence, as well as the simple and complex fluorescence ratios having the chlorophyll fluorescence as basis, is the appropriate parameter to evaluate physiologi- cal responses of sugar beet plants exposed to a short-term, temporary water deficit.

Spin polarization transport in ZnO/La2/3Sr1/3MnO3/LaAlO heterostructures

ZnO/La2/3Sr1/3MnO3 thin fims have been epitaxially grown on LaAlO3 (100) substrates using a pulsed laser deposition (PLD) method. I–V curves of the ZnO/La2/3Sr1/3MnO3 structure were investigated over the temperature range from 50 to 300 K. Analysis of the leakage current demonstrates that Poole-Frenkel emission is the dominant mechanism in our sample. The photoinduced resistance and demagnetization versus temperatures demonstrates that the optical field dominated the photoconductivity mechanism below Curie temperature Tc from different green-light source. The shape and size of the barrier were changed by junction interface and interface tensile strain due to optical and magnetic external perturbations which the photoinduced characteristics modified the carrier density at the ZnO/LSMO interface. Magnetoresistance (MR) and photoinduced resistance effect is observed and the MR is related to the electron spin-dependent scattering and the interface resistance of the heterostructure. Moreover, the La1-xSrxMnO3/ZnO heterostructure exhibited a positive colossal magnetoresistance (MR) effect over the range of 50–300 K.

The Research of LED Lights Model Based on Road Lighting in Mesopic Vision

This paper analyzes the structural features of the human eye in the middle of the road lighting visual state of the visual request of road lighting in the Mesopic range of lighting, road lighting standards to build a white and green LED light source distribution model and defines the sharpness of the image according to the model function. In the Matlab7.1 environment, high pressure sodium yellow light LED white light and LED white and green background light, the model simulation analysis of the image clarity, results show that, in the Mesopic same brightness level state road lighting selection white and green the LED light source has better clarity and sensitivity.

Visible‐Light‐Promoted CC Bond Cleavage: Photocatalytic Generation of Iminium Ions and Amino Radicals

Although the use of photons as reagents has enjoyed an incredibly rich history, the use of photons of red-shifted wavelengths, particularly those extending into what is known as the visible region (i.e., wavelengths ranging from 380 nm to 750 nm), in the context of promoting synthetically attractive organic transformations has attracted considerable attention only very recently. Thanks to the pioneering work from the groups of MacMillan, Yoon, Stephenson, and others, this field has already demonstrated outstanding accomplishments and holds promise for uncovering new catalysis concepts and synthetic applications. Such efforts would most likely be fueled and accelerated in the future by the increasing demand for developing environmentally benign chemical processes with reduced energy consumption, as well as by the latest advancements in commercializing green light sources such as organic light-emitting diodes (OLEDs). Not surprisingly, as organic compounds generally cannot absorb visiblelight, the use of visible light as an effective means to initiate organic reactions must require a photosensitization strategy. Such sensitizers function as useful photocatalysts, the most widely employed example being a ruthenium(II)–polypyridine complex such as [Ru(bpy)3Cl2] (bpy= bipyridine). [8] As photocatalysts with suitable photoredox potentials and their commercial availabilities are both highly limited, it is thus readily recognizable that the success of unlocking the full potential of visible-light photocatalysis for synthetic reactions of broad utility lies in the identification of efficient methodologies for the convenient photocatalytic generation of some of the most versatile reactive species, but with the aid of only a few known sensitizers. Among the synthetic chemists arsenal, iminium ions and radicals clearly stand out as reactive intermediates of major significance. The goal that considerably motivates us is, thus, to devise and possibly implement new visible-lightpromoted photocatalysis strategies which would allow facile production of structurally robust iminium ion or radical intermediates, and preferably, in a one-pot and controllable fashion. We believe that the ability of accessing such intermediates having variable substituents or structurally editable functionalities would ensure the “freedom-of-operation” to be conveniently practiced while merging them into intended catalysis cycles. In this context, it should be highlighted that the groups of Stephenson, Xiao, and Rueping have described significant examples of oxidative C H functionalizations through in situ generation of iminium ions under visible-light photoredox conditions (Scheme 1).

Diode-pumped green light source based on intracavity sum frequency generation

We report a continuous-wave (CW) green laser emission by sum-frequency mixing in Nd:YVO4 and Nd:YLF crystals. Using type-II critical phase-matching (CPM) KTP crystal, a green laser at 539 nm is obtained by 914 and 1313 nm intracavity sum-frequency mixing. The maximum laser output power of 388 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 388 mW, the output stability is better than 4.6%.

Enhanced green emission from UV down-converting Ce3+–Tb3+ co-activated ZnAl2O4 phosphor

Ce3+–Tb3+ co-activated ZnAl2O4 powder phosphors were prepared by a solution combustion method using urea as a fuel. X-ray diffraction characterization showed that all the powders crystallized in the well known cubic spinel phase of ZnAl2O4. An enhanced down-converted green emission associated with the 5D4→7F5 transitions of Tb3+ ions was observed at 543 nm from the ZnAl2O4:Ce3+, Tb3+ powders with different concentrations of Ce3+ and Tb3+. It was inferred from the fluorescence decay data that the enhancement was due to energy transfer from Ce3+ to Tb3+. Further, cathodoluminescence intensity degradation of the ZnAl2O4:Ce3+, Tb3+ powder phosphors was investigated when the powders were irradiated with 2 keV electrons. X-ray photoelectron spectroscopy was used to analyze the chemical and electronic states of individual elements before and after electron irradiation. The ZnAl2O4:Ce3+, Tb3+ phosphor was evaluated to be used as a UV down-converting layer in conventional silicon photovoltaic cells or as a source of green light in field emission display technologies.

Plastic Optical Fiber Sensing of Alcohol Concentration in Liquors

A simple optical fiber sensing system of alcohol concentration in liquors has been studied. In this sensor head, a mixture polymer of novolac resin and polyvinylidenefluoride (PVDF) with a ratio of 9 : 1 was coated as a sensitive cladding layer on the plastic fiber core made of polystyrene-(PS-)coated polycarbonate (PC). Using this sensor head and a green LED light source, it was confirmed that alcohol concentration in several kinds of liquors from beer to whisky can easily be measured with a fast response time less than 1 minute.

Carbon Nanotubes Cathode of Field Emission Lamp Prepared by Electrophoretic Deposition

Field emission lamp is a kind of green and low energy loss light source. Carbon nanotube cathode of field emission lamp was prepared by electrophoretic deposition. Two types of solute salt were added in electrophoretic solution separately, which were used to prepare two types of carbon nanotubes films on identical aluminum sheets by electrophoretic deposition method. Scanning electron microscopy(SEM) were used to observe the surface morphology of the films. The field emission properties of the films were tested by using a diode structure. The turn-on field of the film deposited with CsNO3 / Ca(NO3)2 4H2O solution was 0.7V/μm. The current density of the film was about 4000mA/cm2 at an electric field of 1.8V/μm. While corresponding data by using Mg(NO3)2 6H2O solution was 0.8V/μm and 3800mA/cm2. It is concluded that the field emission properties of the deposited film cathode by using CsNO3/ Ca(NO3)2 4H2O solution better than that using Mg(NO3)2 6H2O solution.

LED Lighting Application in Long Railway Tunnels

Hong Kong is expanding its railway network to fulfill the needs of housing, transportation and economic development in strategic growth areas and meet cross-boundary passenger demands. Hong Kong’s unique high density urban development pattern prohibits overground railways. This implies longer tunnels are required to connect those areas. Long railway tunnel brings a challenge to the design and the electrical and mechanical systems installed. Lighting is one of the crucial safety systems equipped in the railway tunnel and with the modern emphasis in environmental protection, a more energy conservative and cost-effective design approach is needed. LED is a new form of green light source which is becoming more and more popular in recent urban road lighting and commercial and household application. However, its application to railway tunnel is still rare. The paper reviews the LED lighting technology and stresses on its application to address the long tunnel lighting design requirements and special railway tun...

Photodynamic Hyperthermal Therapy with Indocyanine Green (ICG) induces Apoptosis and Cell Cycle Arrest in B16F10 Murine Melanoma Cells

We examined the effects of photodynamic hyperthemal therapy (PHT), which is a combination of photodynamic therapy (PDT) and hyperthermia (HT), on the apoptosis and cell cycle progression of murine melanoma B16F10 cells. The percentage of apoptotic cell was determined by flow cytometry using fluorescein isothiocyanate (FITC)-conjugated Annexin V and propidium iodide (PI) double staining. The cell cycle analysis was performed by PI staining with flow cytometry. The expression of cyclins and heat shock protein 70 (Hsp70) were examined by a Western blotting analysis. PHT induces death in B16F10 cells, and PHT-mediated apoptosis occurred acutely and persistently in vitro. Our study demonstrated that PHT using indocyanine green (ICG) and near infrared (NIR) light source induces apoptosis and G0/G1 cell cycle arrest in the B16F10 cells.

An evaluation of a novel instrument for measuring macular pigment optical density: the MPS 9000

Of the antioxidants found in the human retina, only the macular carotenoid quantities can be estimated noninvasively (albeit in a collective fashion), thus facilitating study of their role in that tissue. The aim of this study was to evaluate concordance between macular pigment optical density (MPOD) values recorded on a commercially available instrument, the MPS 9000, with those of an already validated heterochromatic flicker photometry instrument. Also, we assessed and compared test-retest variability for each instrument. Macular pigment optical density at 0.5 retinal eccentricity was measured using two different heterochromatic flicker photometers, the MPS 9000 and the Macular Densitometer(TM), in 39 healthy subjects. Test-retest variability was evaluated separately for each instrument by taking three readings over a 1-week period in 25 subjects. There was a moderate positive correlation for MPOD at 0.5° of retinal eccentricity between the MPS 9000 and the Macular Densitometer described by the linear equation y = 0.763x + 0.172 (r = 0.68, p < 0.001, r(2) = 0.46); however, a paired-samples t-test showed a significant difference in terms of mean values, with a bias of lower MPOD values being yielded by the MPS 9000 (t = -4.103, p < 0.001). Bland-Altman analysis indicated only moderate agreement between the two instruments, reflected in 95% limits of agreement of 0.1 ± 0.27. Inter-sessional repeatability, expressed as a coefficient of repeatability, ranged from 0.18 to 0.21 [mean (±SD): 0.19 (0.02)] for the MPS 9000 and from 0.11 to 0.12 [mean (±SD): 0.12 (0.01)] for the Macular Densitometer. The results demonstrate that the MPS 9000 consistently yields MPOD readings, which are lower than that found with the Macular Densitometer, and exhibits substantial test-retest variability.

Catalytic Modulation on the Regioselectivity of the Photosensitized Oxidation of α-Pinene with Molecular Oxygen under Sodium Lamp Irradiation

A simple and efficient photosensitized catalytic oxidation approach for α-pinene with molecular oxygen in a temperature-controlled reactor with sparged dioxygen as oxidant and an immersed high-pressure sodium lamp as a green irradiation light source was developed. The effects of various catalysts and reaction parameters on reaction performance were studied. The results indicated that 98% conversion with 84% total selectivity for verbenone and verbenol was obtained when N,N '-dimethylformamide (DMF) was used as a solvent. The product distributions were remarkably affected by the reaction media and DMF was found to especially modulate the regioselectivity of the products. Moreover, a possible photosensitized catalytic oxidation reaction mechanism in DMF is proposed and a clear acid-base synergetic catalysis effect was evident. The relationship between chemical reactivity and selectivity was modeled using density functional theory at the B3LYP/6-311+G(d) level from optimized molecular configurations. 发展了一种简单有效的 α-蒎烯光敏催化氧化方法, 该方法以高压钠灯为绿色光源, 内循环氧气作为氧化剂和搅拌气, 自制水浴式光化学反应器. 考察了催化剂种类和反应条件对 α-蒎烯转化率和产物选择性的影响. 结果表明, α-蒎烯可通过催化一步生成单萜醇、醛和酮, 且通过催化剂的酸碱协同作用可调节产物的区域选择性. 当以 N , N -二甲基甲酰胺为溶剂时, α-蒎烯的转化率可达 98%, 主产物马鞭草烯酮和马鞭草烯醇的总选择性达到了 84%. 此外, 还探讨了 N , N -二甲基甲酰胺酸碱协同催化的作用机理, 并利用密度泛函计算结果对 α-蒎烯分子中化学反应活性和产物选择性之间的对应关系进行了合理的解释. An efficient catalytic modulation approach for the photosensitized oxidation of α-pinene with molecular oxygen was developed. A relationship between the chemical reactivity and selectivity was modeled using density functional theory.

A Novel High Efficiency Solution of High Power LED Lighting

High power LED is a kind of ideal green lighting source, which owns longer life, higher efficiency and lower electricity power consumption than incandescent lamps and fluorescent bulbs. Constant current driver is the most key factor for high power LED’s premium properties. Based on the specific chip LM3478, a novel Boost DC/DC converting circuit to drive LED was proposed. The whole circuit structure was simple, and owned high reliability with over current protection. The circuit operates continuous current mode (CCM), with normal supply voltage 12V. The constant output current is 700mA, which can drive two-row LED series, 5 LEDs at least each series. The test results show that the electricity efficiency is up to 93.20% and that the output current deviation is 7.71%. The operating temperature range is -40~+125°C.

Diode laser pumped green light source based on intracavity sum frequency generation

We report a continuous-wave (CW) green laser emission by sum-frequency mixing in Nd:YVO4 and Nd:YLF crystals. Using type-II critical phase-matching (CPM) KTP crystal, a green laser at 539 nm is obtained by 914 and 1313 nm intracavity sum-frequency mixing. The maximum laser output power of 388 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 388 mW, the output stability is better than 4.6%.

Green high‐power light sources using InGaN multi‐quantum‐well structures for full conversion

AbstractWe investigate the possibility to obtain efficient green light sources for high‐power applications by full luminescence conversion via InGaN/GaN multi‐quantum‐well (MQW) structures. Using an ultraviolet (UV) light‐emitting diode (LED) for optical pumping of a forty‐period (40x) MQW structure emitting in the green spectral range, we show that a luminous flux comparable to the best reported values for direct green LEDs can be achieved. The position of the efficiency maximum on the excitation density axis is shifted by an order of magnitude to an equivalent of 28 Acm–2 while maintaining comparable absolute values. We propose the concept of processing suitable platelets placed directly on a pump LED as a general experimental tool to determine absolute efficiency values of structures that cannot be pumped by electrical means (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

A40 偏光高速度カメラによるゼラチン脳モデルの脳内応力解析(人体のモデル化,挙動計測)

We examined the stress distribution occurring in a two-dimensional sagittal gelatin model using optical stress analysis to make clear the mechanism of the intracranial damage in the shaken baby syndrome (SBS). We modified Holbourn's model and added the lateral ventricle. The device consisted of rotation table, green light source, polarizer, gelatin model and high-speed polarized camera. The model oscillated rotationally in the sagittal direction with 60 degrees of central angle and 2-3Hz of frequency. The average peak values of linear acceleration, angular velocity and acceleration in flexion were 1.7G, 3.5rad/sec and 183.4rad/sec^2, respectively. In color image sequence for major polarization axis direction indicating stress generations, color changes occurred clearly in frontoparietal region near by brain surface just before full flexion. We consider the results may be important for explaining the mechanism of brain injuries in the SBS such as subdural hemorrhage or brain damage.

Green Bulb Light Source Induced Epoxy Cationic Polymerization under Air Using Tris(2,2′-bipyridine)ruthenium(II) and Silyl Radicals

Green Bulb Light Source Induced Epoxy Cationic Polymerization under Air Using Tris(2,2′-bipyridine)ruthenium(II) and Silyl Radicals

Photoconductivity in BiFeO 3/La 0.7Sr 0.3MnO 3 heterostructure

In this letter, an oxide heterostructure has been fabricated by successively growing La 0.7Sr 0.3MnO 3 (LSMO) and BiFeO 3 (BFO) layers on LaAlO 3 (100) by pulsed laser deposition. Analysis of the leakage current at different temperature demonstrated that the Poole–Frenkel dominated the leakage current mechanism. Additionally, the BiFeO 3/La 0.7Sr 0.3MnO 3 heterostructure exhibits a positive colossal magnetoresistance (MR) effect over a temperature range of 50–320 K. The maximum MR values are determined to be about 45.32% at H = 0.5 T and 28.34% at H = 0.3 T. At last, we report photoconductivity in BiFeO 3/La 0.7Sr 0.3MnO 3 film under illumination from 160 mW/cm 2 and 200 mW/cm 2 green-light source, and photoconductivities increase with the intensity of light enhanced.

Accurate color measurement methods for medical displays

The necessity for standard instrumentation and measurements of color that are repeatable and reproducible is the major motivation behind this work. Currently, different instrumentation and methods can yield very different results when measuring the same feature such as color uniformity or color difference. As color increasingly comes into play in medical imaging diagnostics, display color will have to be quantified in order to assess whether the display should be used for imaging purposes. The authors report on the characterization of three novel probes for measuring display color with minimal contamination from screen areas outside the measurement spot or from off-normal emissions. They compare three probe designs: A modified small-spot luminance probe and two conic probe designs based on black frusta. To compare the three color probe designs, spectral and luminance measurements were taken with specialized instrumentation to determine the luminance changes and color separation abilities of the probes. The probes were characterized with a scanning slit method, veiling glare, and a moving laser and LED arrangement. The scanning slit measurement was done using a black slit plate over a white line on an LCD monitor. The luminance was measured in 1 mm increments from the center of the slit to +/- 15 mm above and below the slit at different distances between the probe and the slit. The veiling glare setup consisted of measurements of the luminance of a black spot pattern with a white disk of radius of 100 mm as the black spot increases in 1 mm radius increments. The moving LED and laser method consisted of a red and green light orthogonal to the probe tip for the light to directly shine into the probe. The green light source was moved away from the red source in 1 cm increments to measure color stray-light contamination at different probe distances. The results of the color testing using the LED and laser methods suggest a better performance of one of the frusta probes at shorter distances between the light sources, which translates to less contamination. The tails of the scans indicate the magnitude of the spread in signal due to light from areas outside the intended measurement spot. The measurements indicate a corresponding glare factor for a large spot of 140, 500, and 2000 for probe A, B1, and B2, respectively. The dual-laser setup suggests that color purity can be maintained up to a few tens of millimeters outside the measurement spot. The comparison shows that there are significant differences in the performance of each probe design, and that those differences have an effect on the measured quantity used to quantify display color. Different probe designs show different measurements of the level of light contamination that affects the quantitative color determination.