最新刊期
卷 36 ， 期 3 ， 2015
- 摘要：In order to overcome the shortcoming of (Sr, Ca) AlSiN3:Eu2+ red phosphor on the thermal quenching and long term anti-degradation, which results in obvious light efficiency decay and color shift and have adverse impact on the light quality of white LED, in this paper, alkaline earth metal ions and rare earth metal ions are doped into (Sr, Ca) AlSiN3:Eu2+ red phosphor and their influence on the thermal quenching and long-term performance are explored. The results show that the doping Li+-Dy3+, Li+-Ho3+ ion can play important role to promote the anti-degradation performance effectively, and suppress the color shift during long term aging simultaneously.关键词：WLED;red phosphor;long term performance147|102|2更新时间：2020-08-12
- 摘要：Cr3+- and Yb3+-doped YAG powder samples were prepared and the energy transfer (ET) mechanism in the samples was evaluated by the photoluminescence (PL), photoluminescence excitation (PLE) and light-emitting lifetime. By taking advantage of the spin allowed 4A2 → 4T2 and 4A2→4T1 absorption of Cr3+ and the efficient energy transfer from Cr3+ to Yb3+, the broadband spectral conversion makes Yb3+:2F5/2→2F7/2 transition give off a desirable emission around 1 000 nm, which is according to the maximum spectral response of c-Si solar cells, and hence would lead to the enhancement of silicon solar photovoltaic conversion efficiency.关键词：Cr3+;Yb3+;NIR emission;energy transfer151|118|4更新时间：2020-08-12
- 摘要：Y2Ti2O7:xTm(x=0.005, 0.01, 0.03, 0.05) phosphors were prepared by sol-gel method and sintered at different temperatures. The structure, morphologies, and luminescence properties of samples were characterized by X-ray diffraction (XRD), TEM, and fluorescence spectrophotometer, respectively. The XRD patterns indicate that the structure of samples belongs to pyrochlore structure, and is not changed by the doping of Tm3+. Blue emissions centered at 456 nm, corresponding to 1D2→ 3F4 transition of Tm3+, are detected under 361 nm excitation. The best luminescence performance is derived when the sintering temperature is 1 000 ℃ for Y2Ti2O7:0.01Tm3+. Furthermore, the emission intensity at 456 nm increases and then decreases with the increasing of Tm3+ concentration. The most intense emission is obtained when the mole fraction of Tm3+ is 1%, which indicates that the concentration quenching happens when the mole fraction of Tm3+ exceeds 1%.关键词：Y2Ti2O7:Tm3+;sol-gel method;concentration quenching95|114|1更新时间：2020-08-12
- 摘要：A simple method for HgTe/CdS/ZnS multi-shell quantum dots (QDs) synthesizing was developed. Firstly, HgTe core QDs were synthesized in aqueous solution with 1-thioglycerol as the stabilizer. Then, CdS and ZnS shells were grown on the surface of HgTe core by epitaxial growth method. The resultant HgTe/CdS/ZnS multi-shell QDs have stable near-infrared light-emitting property. This synthetic method contains only three steps with the advantages of simple operation and low cost. The experimental results indicate that HgTe/CdS/ZnS multi-shell QDs can reach the highest fluorescence quantum yield of 36% as the reaction solution (pH=11.0) is heated reflux for 4 min at 90 ℃.关键词：HgTe/CdS/ZnS quantum dots;epitaxial growth;fluorescence quantum yield123|161|0更新时间：2020-08-12
- 摘要：GaN nanorods were fabricated by ICP using Ni self-assembled nanodots as etching mask.The morphology was checked by scanning electron microscopy (SEM), and the optical property was characterized by the photoluminescence (PL) spectra at room temperature. The PL intensity of GaN nanorods was enhanced about 2.6 times compared to that of as-grown GaN films. Then, GaN nanorods were dipped into the KOH solution for 40 min in order to heal the etch damage. After the treatment, the PL intensity was enhanced again. The temperature-dependent PL was measured to estimate IQE. The results show that the enhancement of PL intensity is due to the higher IQE after the KOH treatment.关键词：GaN nanorod;KOH treatment;photoluminescence(PL);quantum efficiency131|176|2更新时间：2020-08-12
- 摘要：Mg and Ca doped Bi4Ge3O12 (BGO) crystals were grown by using Czochralski (Cz) technique, and Cl doped BGO crystal was prepared by Vertical Bridgman (VB) method. The absorption, photoluminescence (PL) and PL lifetime spectra were systematically investigated. The results reveal that the emission intensity of these doped BGO is weaker than that of pure BGO in visible region. Near infrared (NIR) emission is observed in doped BGO under 808 nm and/or 980 nm laser diodes (LDs) excitation, and the NIR emission should be ascribed to a changed Bi-related active center or lower valence Bi ions. The valence state of doped ions could be key to achieving the NIR emission in BGO crystals, and the doped ions with same valence could play the similar roles in our experiments.关键词：Bi4Ge3O12;photoluminescence;near infrared104|98|0更新时间：2020-08-12
- 摘要：InxGa1-xAs was deposited on (100) GaAs substrate by MOCVD with the two-step growth. The effects of buffer layer thickness on the surface morphology, crystalline quality, and alloy order degree of the epilayer were analyzed by SEM, AFM, XRD, and Raman spectroscopy, respectively. The distribution of dislocations in epilayer was observed by TEM and the dislocation density was calculated. The experiment results show that the buffer layer thickness of InxGa1-xAs heterostructure has the optimal value.关键词：two step growth;GaAs;InGaAs;MOCVD100|86|2更新时间：2020-08-12
- 摘要：GeO2-B2O3-SiO2 magneto-optical glasses with high Tb3+ content were prepared by high temperature melting technique. The effect of Tb3+ content on the Faraday effect, luminescent properties and optical basicity was studied. The results show that Verdet constant and optical basicity increase with the increasing of Tb2O3 content. All samples emit bright greenish-yellow luminescence, and the glass has a higher Verdet constant of -5 000 min·T-1·cm-1 at 632.8 nm when the mole fraction of Tb2O3 is 70%. The distances among Tb3+ ions become shorter with the increasing of Tb2O3 content due to the concentration quenching effect, therefore, the cross-relaxation effect is enhanced, and the effective luminous intensity and lifetime decrease.关键词：magneto-optical glass;optical basicity;Tb3+;photoluminescence106|149|1更新时间：2020-08-12
- 摘要：A series of electron capture materials Sr0.98-xAl2O4:0.02Eu2+,xTm3+(x=0, 0.01,0.02, 0.03, 0.04, 0.05) were synthesized by a conventional solid-state reaction method. The deeper new trap (TB) was introduced into the SrAl2O4:Eu2+ phosphor lattice by the co-dopant of Tm3+ ions to optimize the properties of the ETM phosphor. Meanwhile, the trap concentration of intrinsic shallow trap (TA) was increased. The properties of photo-stimulated luminescence (PSL) and thermoluminescence (TL) in the series samples were investigated. It is found that TB is responsible for the performance of PSL. The most efficient initial PSL can be obtained when the co-doping mole fraction of Tm3+ is 0.03, which keeps the correspondence with the strongest TL intensity of TB. Besides, the phosphors show a PSL afterglow under 980 nm stimulation, which can be ascribed to the re-trapping of TA as the electrons firstly excited from TB will be re-trapped by the empty TA to generate the PSL afterglow.关键词：electron capture;photo-stimulated luminescence;thermo luminescence;trap118|133|2更新时间：2020-08-12
- 摘要：TeO2-WO3-La2O3-AgNO3 glass samples were prepared via melt-quenching method, and the transparent tellurite glasses with Ag nanocrystallites were obtained by heat treatment. The transmittance spectra and stimulated emission spectra of the glass samples with different heat-treatment systems were measured. Ag nanocrystallites in glasses were examined by HR-TEM images, and the luminescence enhancement mechanism was also analyzed. The results show that Ag nanocrystallites are crystallized by heat treatment under 390 ℃ for 15 min. The two-photon absorption process of green and red light in glass does not change after Ag nanocrystallites are introduced. Because of the enhanced local electric field generated by Ag nanocrystallites, the up-conversion and near-infrared luminescence of Ag-contained glass increase, of which the green light intensity of the glass containing Ag nanocrystallites is 5 times as much as that of glass without Ag nanocrystallites.关键词：tellurite glass;Er3+/Yb3+ co-doped;Ag nanocrystallites;local field enhancement122|55|2更新时间：2020-08-12
- 摘要：CdSe quantum dots were prepared by the reaction of CdCl2·2.5H2O, Na2SeO3 and NaBH4 in water and in the presence of mercaptosuccinic acid as stabilizer. The fluorescence of quantum dots can be significantly quenched by copper ions. However, in the presence of penicillamine, copper ions were released from the quantum dots and thus restored the fluorescence of quantum dots. A new type of fluorescence turn-on assay for detection of penicillamine using quantum dots/copper ion ensemble is developed. Under the selected conditions, the response was linearly proportional to the concentration of penicillamine from 1 to 72 μg/mL, the limit of detection was 0.031 μg/mL. The developed method has been successfully applied to the detection of penicillamine in real samples with satisfactory results.关键词：quantum dots;copper ions;penicillamine;fluorescence;determination114|36|3更新时间：2020-08-12
- 摘要：Using radio frequency magnetron sputtering technique, N doped ZnO films were prepared on quartz substrate with mixture of nitrogen and argon as sputtering gas, and the nitrogen flux was 0, 8, 20, 32 mL/min, respectively. The effects of the nitrogen flux on the structure and properties of N doped ZnO thin films were investigated. It is found that the resistivity of the films increases with the increasing of the nitrogen flux, and the content of NO and (N2)O increases, too. When the nitrogen flux is 8 mL/min, the deposited film has the best effective doping efficiency of nitrogen. Furthermore, the thickness of ZnO: N films decreases with the nitrogen flux increasing.关键词：thin ZnO films;N doped;sputtering ambient;photoelectric properties107|115|0更新时间：2020-08-12
- 摘要：Series of oxyfluoride phosphors Sr3-xEuxAl1-yByO4-yNyF were prepared by the conventional solid-state reaction. The composition and structure of the Sr3AlO4F:Eu3+ could be adjusted by doping BN into the host, and then the luminescence properties of Sr3-xEuxAl1-yByO4-yNyF would be affected. X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), scanning electron microscopy (SEM), as well as photoluminescence (PL) spectra were utilized to characterize the samples. Under the excitation of UV light, Sr3-xEuxAl1-yByO4-yNyF exhibits the characteristic emissions of Eu3+, and the luminescence properties of Eu3+ can be enhanced by adjusting doping concentration of BN in the host. The corresponding mechanism has been proposed briefly.关键词：Sr3AlO4F;luminescence in Eu3+;red phosphor;BN144|104|1更新时间：2020-08-12
- 摘要：According to the transition rates equation of the ground state population and the propagation equation, the numerical model of the group velocity slowdown was established. The relationship between the gain and pump power was analysized. In the absorption area of Tm3+-dopedoptical fiber, the oscillation leads the pulse to experience absorption saturation, and the propagation delays. In the gain area of Tm3+-doped optical fiber, this effect induces the pulse to experience gain saturation, and the propagation is in advance. According to the theoretical calculation, the group velocity slowdown is tunable due to coherent population oscillation in the Tm3+-doped optical fiber amplifier at room temperature.关键词：Tm3+-doped optical fiber;absorption saturation;gain saturation;slow light127|175|0更新时间：2020-08-12
- 摘要：The cladding mode frustrated total internal reflection (CMFTIR) effect and its sensing mechanism were analyzed and demonstrated. The method of acquiring remarkable CMFTIR effect was proposed. This method uses the distortion of fiber mode field caused by macro-bending to excite cladding mode. By using this method, the CMFTIR effect could be enhanced remarkably and be used for liquid level detection. The experiment shows that CMFTIR effect is relatively weak and easy to be submerged by strong background noises. In order to solve this problem, the method of improving signal-to-noise ratio was proposed by using macro-bend coupling and dark-field signal. Then, the twisted macro-bend coupling liquid level probe and its encapsulation structure were designed. The experiment results show that dark-field signal has obvious advantage on signal-to-noise ratio, and the sensor realizes extinction ratio above 3.7 dB. Compared with the same kind of probes, the sensor is robust, low-cost and easy to manufacture.关键词：POF fiber;liquid level sensor;cladding mode frustrated total internal reflection369|95|2更新时间：2020-08-12
- 摘要：A new method using wafer modified by CdTe quantum dots to detect the concentration of Pb2+ was discussed in this paper. The surface of glass wafer was modified by means of hydroxylation and aminosilanization to obtain amino-modified slide. The thioglycolic acid-capped CdTe quantum dots synthesized in aqueous phase were successfully coupled on the surface of amino-modified slide by using EDC/NHS activation reaction. Some influence factors were discussed, such as molar ratio of QDs/DEC, activation time, coupling temperature and coupling time. The results show that the functional wafer with QDs/DEC molar ratio of 1:30, activating time of 1 h, reacting time of 4 h, and reacting temperature of 40 ℃ has the best fluorescence performance. The obtained wafers were successfully used to measure the concentration of Pb2+ in aqueous solution. The quenched fluorescence intensity of functional wafer is linearly proportional to the concentration of Pb2+ between 1.0×10-9 and 4.0×10-8 mol·L-1 with a detection limit of 3.8×10-9 mol·L-1. Good selectivity is also proved by interfering ion experiment. This proposed method can be used to detect Pb2+ sensitively and accurately.关键词：functional wafer;CdTe quantum dots;surface treatment;Pb2+119|158|5更新时间：2020-08-12
- 摘要：In order to analyze the control factors of LED array illumination on the curved surface plate, some experiments were designed by using Taguchi method and simulated via TracePro software. Then, ANOVAtheory was integrated to evaluate the influence of the control factors on the illumination, so that the control factors could be optimized efficiently. The experiment results show that the number of LEDs is the main influence on both illuminance uniformity(81.84%) and maximum illumination(91.58%). Furthermore, the best combination of the control factors can be obtained by adjusting the angle between the LED chips and the optical axis. This paper provides a theoretical basis to solve the illumination problem of the curved surface lighting.关键词：Taguchi method;curved surface;LED;illumination problem;ANOVA179|111|12更新时间：2020-08-12
- 摘要：Multilayer polyethylene glycol/titanium dioxide (PEG/TiO2) one-dimensional photonic crystal films were fabricated by using spin coating technique. PEG/TiO2 one-dimensional photonic crystal membranes with different photonic stopbands were fabricated by changing the time of spin coating, spin speed and the mass concentration of polyethylene glycol solution. The experiment results show that PEG/TiO2 film has a dual response to dimethyl sulfoxide (DMSO) and strong alkali solution.关键词：one-dimensional photonic crystals;PEG/TiO2;spin coating method119|317|4更新时间：2020-08-12
- 摘要：The broadband THz generation from 0.2 to 2.5 THz was measured as a function of pump intensity in a single pure gallium selenide crystal based on the optical rectification of ultrafast laser pulses. Two-photon absorption at 800 nm can generate free charge carriers which can absorb the generated THz radiation, and finally attenuate THz output. The result indicates that the pump intensity dependence of ouput THz radiation changes from square to sub-linear relationship and the saturation of output THz radiation appears at high pump intensity. To study the impact of two photon absorption on THz generation, the two photon absorption coefficient of GaSe at 800 nm is measured to be 0.165 cm/GW, which is determined by the measured nonlinear transmission. The THz output fitting result taking account of the free charge carrier absorption cross section of 1×10-15 cm2 is consistent with the experiment data very well. This estimation result can be used to optimize the conversion efficient of THz generation in GaSe crystal under intense laser pump.关键词：GaSe crystal;two photon absorption;THz generation;absorption cross section164|859|3更新时间：2020-08-12
- 摘要：By using ultraviolet absorption spectroscopy detection technique, the real-time monitoring for the concentrations of SO2 and H2S mixed gas was realized. Deuterium lamp was used as a light source, and MAYA2000Pro spectrometer served as spectrograph in the experiment. Based on Beer-Lambert law and absorption spectrum, the formula of SO2 concentration was deduced by choosing very close two points in the absorption spectrum, which could ignore the interference of the scattering and absorption from other gas. The absorption spectrum of H2S gas can be achieved by subtracting the corresponding absorption spectrum of SO2 gas from mixed gas spectrum. At the normal temperature and pressure, the concentration of H2S could be obtained from the absorption peak of H2S absorption spectrum. The measuring accuracy of mixed gas is about 1×10-6(1 ppm). So, our work realizes the real-time monitoring for SO2 and H2S in mixed gas.关键词：atmospheric optics;SO2 gas;H2S gas;absorption spectrum;spectrum technology166|106|6更新时间：2020-08-12
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