共查询到20条相似文献,搜索用时 0 毫秒
1.
We theoretically analyse the temperature effects on a surface plasmon resonance (SPR) sensor in Kretschmann configuration. The temperature effects include the thermo-optic effect and the dispersion of thermal-optic coefficient in the dielectric along with the thermal expansion effect, phonon-electron scattering and electron-electron scattering in the metal layer. We simulate the temperature dependence of the resonance position and the sensitivity of the SPR sensor under wavelength-interrogation and angular-interrogation mode of operation and the differences are pointed out in the two modes. 相似文献
2.
High-Sensitivity Sensor Based on Surface Plasmon Resonance Enhanced Lateral Optical Beam Displacements
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We present a new optical sensor based on surface plasmon resonance (SPIt) enhanced lateral optical beam displacements. Compared with the traditional SPIt methods, the new method provides higher sensitivity to the sensor system. Theoretical simulations show that the refractive index (RI) detection sensitivity of the SPR sensor based on the displacement measurement has a strong dependence on the thickness of the metal film. When the optimal thickness of the metal film is selected, the RI resolutlon of the SPIt sensor is predicted to be 2.2 × 10^-7 refractive index units (RIU). Furthermore, it is found that the incidence angle can be used as a parameter to adjust the operating range of the sensor to different refractive index ranges. 相似文献
3.
We investigate the nanostructure, surface plasmon resonance (SPR) absorption and nonlinear enhancement of Au/Ag alloyed hollow nanoshells prepared by the replacement reaction of Ag nanoparticles in a HAuCI4 aqueous solution. As the volume of HAuCl4 increases from OmL to 0.S mL, the SPR band of the Au/Ag alloyed nanoshells is tuned from 430nm to 780nm, and the third-order nonlinear optical susceptibility is enhanced nearly by an order of magnitude, which indicates a large enhancement of local field in the Au/Ag alloyed hollow nanoshells with hole defects. 相似文献
4.
Design of Highly Sensitive Surface Plasmon Resonance Sensors Using Planar Metallic Films Closely Coupled to Nanogratings
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We investigate the sensitivity enhancement of surface plasmon resonance (SPR) sensors using planar metallic films closely coupled to nanogratings. The strong coupling between localized surface plasmon resonances (LSPRs) presenting in metallic nanostructures and surface plasmon polaritons (SPPs) propagating at the metallic film surface leads to changes of resonance reflection properties, resulting in enhanced sensitivity of SPR sensors. The effects of thickness of the metallic films, grating period and metal materials on the refractive index sensitivity of the device are investigated. The refractive index sensitivity of nanograting-based SPR sensors is predicted to be about 543 nm/RIU (refractive index unit) using optimized structure parameters. Our study on SPR sensors using planar metallic films closely coupled to nanogratings demonstrates the potential for significant improvement in refractive index sensitivity. 相似文献
5.
We use two parallel nano-slits in a silver film to form a surface plasmon Mach Zehnder interferometer (MZI), based on the interference of two surface plasmon waves propagating along the two surfaces of the silver film. Coating the silver film with a photoinduced birefringence polymer film, we achieve optical modulation of the MZI output by changing the refractive index of the polymer film with a pump beam. An on/off ratio 0f 2. 7 is obtained for a probe wavelength of 865 nm. 相似文献
6.
Wenfang Xie 《Solid State Communications》2003,127(5):401-405
Two interacting electrons in a Gaussian confining potential quantum dot are considered under the influence of a perpendicular homogeneous magnetic field. The energy levels of the low-lying states are calculated as a function of magnetic field. Calculations are made by using the method of few-body physics within the effective-mass approximation. A ground state behavior (singlet→triplet state transitions) as a function of the strength of a magnetic field has been found in the weak confinement case as a two-electron quantum dot with parabolic confining potential. 相似文献
7.
W. Pfaff D. Weinmann W. Häusler B. Kramer U. Weiss 《Zeitschrift für Physik B Condensed Matter》1994,96(2):201-206
The influence of excited levels on nonlinear transport properties of a quantum dot weakly coupled to leads is studied using a master-equation approach. A charging model for the dot is compared with a quantum mechanical model for interacting electrons. The currentvoltage curve shows Coulomb lockade and additional finestructure that is related to the excited states of the correlated electrons. Unequal coupling to the leads causes asymmetric conductance peaks. Negative differential conductances are predicted due to the existence of excited states with different spins. 相似文献
8.
The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method (FDTD). The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresponding attenuation factors are calculated. We also present a Y-splitter with 90° splitting angle, each branch in the form of double chains. The transmission efficiencies for different wavelengths are evaluated. 相似文献
9.
Yongxue He Peng He Soack Dae Yoon P.V. Parimi F.J. Rachford V.G. Harris C. Vittoria 《Journal of magnetism and magnetic materials》2007
A magnetic field tunable, broadband, low-loss, negative refractive index metamaterial is fabricated using yttrium iron garnet (YIG) and a periodic array of copper wires. The tunability is demonstrated from 18 to 23 GHz under an applied magnetic field with a figure of merit of 4.2 GHz/kOe. The tuning bandwidth is measured to be 5 GHz compared to 0.9 GHz for fixed field. We measure a minimum insertion loss of 4 dB (or 5.7 dB/cm) at 22.3 GHz. The measured negative refractive index bandwidth is 0.9 GHz compared to 0.5 GHz calculated by the transfer function matrix theory and 1 GHz calculated by finite element simulation. 相似文献
10.
The effect of bromine methanol (BM) etching and NH4F/H2O2 passivation on the Schottky barrier height between Au contact and semi-insulated (SI) p-Cd1−xZnxTe (x ≈ 0.09-0.18) was studied through current-voltage (I-V) and capacitance-voltage (C-V) measurements. Near-infrared (NIR) spectroscopy technique was utilized to determine the Zn concentration. X-ray photoelectron spectroscopy (XPS) for surface composition analysis showed that BM etched sample surface left a Te0-rich layer, however, which was oxidized to TeO2 and the surface [Te]/([Cd] + [Zn]) ratio restored near-stoichiometry after NH4F/H2O2 passivation. According to I-V measurement, barrier height was 0.80 ± 0.02-0.85 ± 0.02 eV for Au/p-Cd1−xZnxTe with BM etching, however, it increased to 0.89 ± 0.02-0.93 ± 0.02 eV with NH4F/H2O2 passivation. Correspondingly, it was about 1.34 ± 0.02-1.43 ± 0.02 eV and 1.41 ± 0.02-1.51 ± 0.02 eV by C-V method. 相似文献
11.
Babaev A. A. Dubavik A. Cherevkov S. A. Parfenov P. S. Baranov M. A. Litvin A. P. 《Optics and Spectroscopy》2018,125(5):743-746
Optics and Spectroscopy - The techniques of preparation of layers of Cu2 – xSe semiconductor plasmonic nanocrystals (SPNC) with plasmonic resonances in near infrared region... 相似文献
12.
We examine the performance of the widely used effective index method (EIM) in the modeling of a sub-wavelength rectangular hole in a real metal. Two different ways of applying the EIM, depending on the dimension (shorter or longer) considered first, are found to give very much different results for the modal characteristics of the modes guided by such structures. It is shown that the EIM gives accurate results only if one starts with the surface plasmon polariton (SPP) mode irrespective of shorter or longer dimension. The present findings should be useful in applying the EIM to analyze apertures of other shapes also. 相似文献
13.
We study the plasmon-assisted transmission of two kinds of slit structures in a 290-nm-thick silver film on a glass substrate. For the two-slit structure, the total transmission intensity spectra displays a complex modulation, which is attributed to different propagation constants of the surface plasmon polaritons (SPPs) on the silver-air and silver-glass interfaces. Replacing one of the two slits by a shallow corrugation results in a simple sinusoidal intensity modulation because of the only effective SPP excitation and propagation on the silver-air interface. These confirm the role of different SPP propagations and interference in the transmission properties of metal nanoslits. 相似文献
14.
Using the finite difference time domain (FDTD) method, we numerically simulate the plasmonic interactions and the optical properties of a metallic nanotube array near a thin metallic film. We show that the energies and intensities of the plasmon resonances depend strongly on the aspect ratio (the ratio of the inner to outer radius) of the nanotube, the separation between the center of the nanotube and the upper surface of the metallic film and the thickness of the film. In the thin film limit, the high-energy localized tube-related plasmons can induce their images on both sides of the metallic film, so the degeneracy state splits into two modes. Based on the nature of the field distribution, we also show clearly the plasmon resonant characteristics that the electromagnetic fields decay away from the surface of the nanotubes and both sides of the metallic film. 相似文献
15.
Yu.P. Bliokh 《Optics Communications》2006,259(2):436-444
It is shown that a smooth metal film (or a plasma layer) can be made transparent for an electromagnetic wave when two identical subwavelength diffraction gratings are placed on both sides of the film. The electromagnetic wave transmission through the metal film is caused by excitation of evanescent surface waves (plasmons) and their transformation into propagating waves at the gratings. A model which is developed analytically shows that the problem of the wave transmission is physically equivalent to the problem of excitation of two coupled resonators of evanescent waves which are formed at the two film surfaces. 相似文献
16.
Using a vectorial dipolar model for multiple surface plasmon-polariton (SPP) scattering [T. Søndergaard, S.I. Bozhevolnyi, Phys. Rev. B 67 (2003) 165405], we investigate the possibility of simultaneous SPP excitation and in-plane manipulation with square-lattice arrays of nanoparticles. The SPP excitation followed by focusing and/or waveguiding of SPP waves is observed with nanoparticle arrays of different shapes, demonstrating the feasibility of the suggested approach. 相似文献
17.
This paper reports on the experimental observation of the displacement of a surface plasmon resonance (SPR) excited by a metallic diffraction grating. This effect is achieved by the use of an electro-optical material composed of nano-sized droplets of liquid crystals dispersed in a host polymer. The average refractive index of this material in the form of a thin film on the undulated metal surface can be modified with the application of an external electric field and to tune the wavelength at which the SPR excitation leads to a reflection minimum. The theoretical design and experimental demonstration of the principle of this component are described. 相似文献
18.
We present a self-consistent model of spin transport in a ferromagnetic (FM)-semiconductor (SC)-FM trilayer structure with interfacial barriers at the FM-SC boundaries. The SC layer consists of a highly doped n2+ AlGaAs-GaAs 2DEG while the interfacial resistance is modeled as delta potential (δ) barriers. The self-consistent scheme combines a ballistic model of spin-dependent transmission across the δ-barriers, and a drift-diffusion model within the bulk of the trilayer. The interfacial resistance (RI) values of the two junctions were found to be asymmetric despite the symmetry of the trilayer structure. Transport characteristics such as the asymmetry in RI, spin-injection efficiency and magnetoresistance (MR) are calculated as a function of bulk conductivity σs and spin-diffusion length (SDL) within the SC layer. In general a large σs tends to improve all three characteristics, while a long SDL improves the MR ratio but reduces the spin-injection efficiency. These trends may be explained in terms of conductivity mismatch and spin accumulation either at the interfacial zones or within the bulk of the SC layer. 相似文献
19.
Nonvolatile Memory Devices Based on Gold Nanoparticle and Poly (N-Vinylcarbazole) Composite 总被引:1,自引:0,他引:1
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A rewritable polymer memory device based on gold nanoparticle doped poly (N-vinylcarbazole) (PVK), which can be easily fabricated by simple spin coating, has been described. An electrical bistable phenomenon is observed in the current-voltage characteristics of this device, and it is found that the electrical bistability is repeatable by proper writing voltage and erasing voltage. The unique behaviour of the devices provides an interesting approach such that doping nanoparticles in polymer can be used to realize high performance nonvolatile polymer memory devices. 相似文献
20.
Yoshihiko Takeda Oleg A. Plaksin Haisong Wang Kenichiro Kono Naoki Umeda Naoki Kishimoto 《Optical Review》2006,13(4):231-234
Optical properties of Au nanoparticle composites and a grid structure of Cu nanoparticle composite were studied. Negative
ion implantation was applied to synthesize Au and Cu nanoparticles in amorphous SiO2 and Al2O3. Au nanoparticles were embedded within a depth of 30 nm by 60keV Au− implantation. The surface plasmon resonance (SPR) of Au:SiO2 and Au: Al2O3 composites shifted to red and to blue, respectively, compared to calculated ones by the Mie theory. Optical nonlinearity
was measured with pump-probe femtosecond spectroscopy and the transient spectrum of Au: Al2O3 composite presented a large red shift from the SPR peak. Image mapping of far-field transmitted intensity of Cu-implanted
SiO2 with a fine grid structure drawn by laser-lithography was observed by a scanning near-field optical microscopy (SNOM) system. 相似文献