共查询到20条相似文献,搜索用时 15 毫秒
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B. Mokhtari N. Cherkaoui Eddeqaqi J. Atangana B. G. Onana Essama T. C. Kofane 《Optical and Quantum Electronics》2014,46(1):155-163
We consider a slab waveguide made of a material with negative permeability and negative permittivity, the surrounding medium is conventional. By using the dispersion relation, we show the dispersion curves from the variation of the core width and other physical parameters. The associated energy flow for several thicknesses of the nonlinear layer waveguide is presented. We discuss possible new types of modes that can occur. It is found that the dispersion curves and the energy flow can be controlled by varying the thickness of the guide, the filling factor and the effective plasma frequency. A numerical simulation is done to well illustrate. 相似文献
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An extended split-step time-domain model for composite coupling structures is reported. Time-dependent coupled-wave equations are solved by splitting of the operators for phase accumulation, forward directional coupling, and reverse Bragg reflection. Through an analysis of an add-drop filter based on a grating-written directional-coupler structure, the proposed modeling method is shown to be an order of magnitude more efficient than the previous methods. 相似文献
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In this study, alumina nanoparticles and film were synthesized by sol–gel method and thermally grown. The chemical composition, morphology, and structural properties of the grain nanostructures of the nanoaggregate aluminum atoms on the silicon surface are characterized by X-ray diffraction, energy dispersive spectroscopy, and scanning electron microscopy techniques which show that the atomic ratio of Al and O elements is about 60:45 and the mass ratio is about 70:31. This point reveals that there is no intermediate layer between Al2O3 and the silicon substrate. In conclusion, this nanoparticle shows good electron conductivity at the surface of a carbon paste electrode that shows its ability in the preparation of a nanosensor in morphine analysis. The linear response range and detection limit were found to be 0.1–550 and 0.03 μmol L?1, respectively. The proposed sensor was successfully applied for the determination of morphine in real samples such as human urine and drug. 相似文献
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This paper reports on a facile technique combined with a simple, sensitive and selective spectrofluorimetric method for the determination of hydrochlorothiazide. In methanol, at pH 8.3 and λex=340, hydrochlorothiazide can remarkably enhance the luminescence intensity of the Eu3+ ion doped in polymethylmethacrylate polymer (PMMA) matrix. This could be due to the energy transfer from hydrochlorothiazide to Eu3+ in the excited stated. At the optimized experimental conditions, the enhancement of the characteristic emission band (617 nm) of Eu3+ ion doped PMMA is directly proportional to the concentration of hydrochlorothiazide with a dynamic range of 5×10?8–1.0×10?5 mol L?1 and detection limit of 8.0×10?9 mol L?1. Application of the suggested method was successfully applied to the determination of hydrochlorothiazide in pharmaceutical preparations and human serum samples, with high percentage of recovery, good accuracy and precision. 相似文献
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《中国光学快报(英文版)》2016,(5)
An evanescent field optical fiber sensor based on a short section of polarization maintaining fiber spliced with a tapered single mode fiber is proposed and experimentally investigated. We mainly focus on the refractive index(RI) and temperature sensing characteristics of this compact device. The transmission spectrum of the resonance wavelength,induced by the interference between the excited low order cladding modes and core modes,shows the quadratic function relationships with RI and linear relationships with temperature. Thus,the proposal of this simple-to-fabricate,compact,and low cost sensor shows its possible potential in the sensitive detection field. 相似文献
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Ionics - A ferrocene-derivative compound, 2, 7-bis (ferrocenyl ethynyl) fluoren-9-one (2,7-BFE), was synthesized and used to construct a modified graphene paste electrode. The electrooxidation of... 相似文献
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We propose a novel fiber Fabry-Perot interferometer (FPI) that incorporates a length of microfiber as its cavity and two fiber Bragg gratings (FBGs) as reflectors. The microfiber FPI is simply fabricated by flame-heated taper-drawing the central spot of an FBG into a section of microfiber. Ambient refractive index (RI) influences the effective index of microfiber, and thus the free spectrum range of the microfiber FPI, resulting in RI sensing. A dual-wavelength fiber laser based on the microfiber FPI is constructed, enabling radio frequency interrogation with high resolution. RI sensitivity of 911 MHz/RIU is experimentally demonstrated for microfiber FPI with equivalent diameter of 1.455 μm. Simulation results indicate that the sensitivity can be further enhanced by reducing the diameter of the microfiber. 相似文献
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We consider a method of holographic registration of laser emission modulated by interaction with an object or a medium whose optical properties vary with time and along one of the coordinates. A reference wave whose frequency varies linearly along a coordinate and with time in the registration plane is used. The method makes feasible the implementation of two-exposure holographic interferometry. Information on the temporal, spectral, and phase characteristics as functions of the coordinate can be obtained during the reconstruction stage.Physics and Spectroscopy Division, Lebedev Physics Institute. Translated from Preprint 131, Lebedev Physics Institute of the USSR Academy of Sciences, Moscow, 1989. 相似文献
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In this work a new method has been employed to synthesize nanocrystalline ZnO powder under hydrothermal conditions at 80 °C using aqueous Zn(NO3)2·6H2O solution and diethylamine (DEA) as the starting materials. The ZnO powder prepared by this novel method was characterized by XRD, energy dispersive X-ray spectroscopy (EDX), FTIR and UV–vis techniques. Calculation based on XRD data revealed ZnO particles to be of nanometer size (∼33 nm). The ZnO powder was subsequently used to make its thin film which exhibited flower like morphology when examined by SEM. Thin ZnO films were sensitized with N719 dye, (Bu4N)2[Ru(dcbpyH)2(NCS)2], and used as photo-anode to construct sandwich type dye-sensitized solar cell (DSSC). With such cells, VOC = 0.680 V, JSC = 0.61 mA cm−2, fill factor = 0.43 and overall conversion efficiency η = 0.23% were achieved on illumination with visible light (80 mW cm−2). 相似文献
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Nakao Masashi Oku Satoshi Tanaka Hidenao Shibata Yasuo Yokoo Atsushi Tamamura Toshiaki Masuda Hideki 《Optical and Quantum Electronics》2002,34(1-3):183-193
A two dimensional (2D) GaAs hole array with a high aspect ratio was successfully fabricated by dry etching techniques using a highly ordered alumina membrane as a mask. The reflection spectra of the GaAs hole array shows characteristics of the photonic bandgap (PBG) calculated by using the 2D triangular lattice structure. Various defect lines were formed etching in the GaAs hole array using focused ion beam. The defect-type PBG waveguide was experimentally demonstrated. 相似文献
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Miyake H Siviloglou GA Puentes G Pritchard DE Ketterle W Weld DM 《Physical review letters》2011,107(17):175302
We have observed Bragg scattering of photons from quantum degenerate ^{87}Rb atoms in a three-dimensional optical lattice. Bragg scattered light directly probes the microscopic crystal structure and atomic wave function whose position and momentum width is Heisenberg limited. The spatial coherence of the wave function leads to revivals in the Bragg scattered light due to the atomic Talbot effect. The decay of revivals across the superfluid to Mott insulator transition indicates the loss of superfluid coherence. 相似文献
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We present rapid synthesis of gold nanoparticles by microwave irradiation method. Sample with average particle size 7.7 nm is obtained from TEM. Linear and nonlinear optical studies of the prepared samples are discussed. Reverse saturable absorption (RSA) at longitudinal surface plasmon resonance (SPR) in gold nanoparticles (Au NPs) have been observed using Z-scan and transient absorption techniques with 532 nm laser pulses. Such RSA behavior makes Au NPs an ideal candidate for optical limiting applications. 相似文献