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1.
采用溶胶-凝胶法在玻璃衬底上制备Ag掺杂于ZnO层的Ag:ZnO/SiO2(AZSO)复合薄膜,采用XRD、SEM、UV-Vis和PL谱等手段对样品的晶体结构、微观形貌、透过率、吸收率及光致发光性能等进行表征,并观察了掺Ag量对复合薄膜光学性能的影响。XRD结果表明:样品经300℃退火处理后出现ZnO及单质Ag衍射峰;由SEM结果可观察到AZSO复合薄膜颗粒分散均匀,表面致密,其断面照片显示了薄膜的双层结构。UV-Vis吸收光谱结果表明:随着复合薄膜中Ag含量的增加,Ag与ZnO之间的电子转移及Ag颗粒的变大促使Ag的特征吸收峰呈现红移和宽化,样品的透过率也随之降低,吸收边向短波长方向移动,禁带宽度减小。PL谱结果表明:由于Ag的掺入减少了ZnO内空穴浓度并对复合薄膜的结构缺陷进行补偿,以及Ag在440nm附近的特征吸收,降低了复合薄膜的发光强度。 相似文献
2.
The ultrafast dynamics of surface electromagnetic waves photogenerated on aluminum film perforated with subwavelength arrays of holes was studied in the visible spectral range by the technique of transient photomodulation with approximately 100 fs time resolution. We observed a pronounced blueshift of the resonant transmission band that reveals the important role of plasma attenuation in the optical response of nanohole arrays. The blueshift is inconsistent with plasmonic mechanism of extraordinary transmission and points to the crucial role of interference in the formation of transmission bands. The transient photomodulation spectra were successfully modeled within the Boltzmann equation approach for the electron-phonon relaxation dynamics, involving nonequilibrium hot electrons and quasiequilibrium phonons. 相似文献
3.
Wan Kuang Alex English Min-Hsiung Shih Jeunghoon Lee Bernard Yurke 《Optics Communications》2010,283(20):4090-24053
The transmission property of metallic films with two-dimensional hole arrays is studied experimentally and numerically. For a triangular lattice subwavelength hole array in a 150 nm thick Ag film, both cavity resonance and planar surface modes are identified as the sources of enhanced optical transmissions. Semi-analytical models are developed for calculating the dispersion relation of the cavity resonant mode. They agree well with the experimental results and full-wave numerical calculations. Strong interaction between the cavity resonant mode and surface modes is also observed. 相似文献
4.
Meng-Dong He Jian-Qiang Liu Zhi-Qiang Gong Yong-Feng Luo Xiaoshuang Chen 《Solid State Communications》2010,150(1-2):104-108
The transmission characteristics of metallic film perforated with an array of asymmetric cross-shaped hole are studied by using the three-dimensional finite difference time-domain method. We find that the wavelengths and intensities of transmission peaks depend strongly on the asymmetric parameters of the cross-shaped hole. The transmission peaks in the structure of asymmetric cross-shaped hole array originate from the splitting of the transmission peak in the corresponding one of symmetric cross-shaped hole array. Moreover, it is also found that the transmission spectra can be adjusted by changing other geometrical parameters of asymmetric cross-shaped hole due to the their effect on the distribution of the oscillating charges on metal surfaces. 相似文献
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6.
Analysis of phase shift of surface plasmon polaritons at metallic subwavelength hole arrays
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We present the transmission spectra of light transmitting a metallic thin film perforated with differently shaped sub- wavelength hole arrays, which are calculated by a plane-wave-based transfer matrix method. We analyze the transmission peak positions and the phase-shift angles of different surface plasmon polariton (SPP) modes by using the microscopic theoretical model proposed by Haitao Liu and Philippe Lalanne [Liu Haitao, and Lalanne Philippe 2008 Nature 452 728], in which the phase shift properties of the SPPs scattered by the subwavelength hole arrays are considered. The results show that the transmission peak position and the minus phase shift angle of the SPP increase as the hole size increases. On the other hand, the effective dielectric constant of the metallic film can be deduced by the microscopic theoretical model. 相似文献
7.
The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the full spectrum of thermal radiation of scalar particles by Kerr black holes can be explicitly derived on the basis of a conformal symmetry arising in the wave equation near the horizon. The simplicity of our approach emphasizes the depth of the connection between conformal symmetry and black hole radiance. 相似文献
8.
We quantitatively analysed the factors contributing to the optical transmission enhancement of a sub-wavelength Sb thin film
lens, using the finite-difference time-domain (FDTD) method. The results show that the transmission enhancement of the dielectric
with a Gaussian distributed refractive index loaded in a sub-wavelength circular hole is not only due to the high refractive
index dielectric, but also due to the specific distributions of refractive index. It is the first study about the effects
of the refractive index distribution on the transmission of a sub-wavelength aperture. This kind of lens has practical applications
in the very small aperture lasers and for near-field optical storage and lithography.
PACS 42.79.Ag; 42.25.Bs; 42.25.Fx 相似文献
9.
杂质银对氧化锌薄膜气敏光学特性的影响 总被引:4,自引:1,他引:3
用反应式射频磁控溅射方法制备了纯氧化锌(ZnO)薄膜和掺Ag的ZnO气敏光学传感薄膜。测量了这些薄膜在NOx气体中的透射光谱,然后由透射光谱获得了灵敏度的变化规律,发现掺Ag后的ZnO薄膜对NOx气体的灵敏度高于纯ZnO薄膜,用俄歇电子能谱(AES)测试了这些薄膜的组分,发现当掺Ag量为5%时灵敏度最高,并结合朗缪尔(Langmuir)型吸附平衡关系式解释了这些现象,理论和实验结果能很好的相符。 相似文献
10.
van Nieuwstadt JA Sandtke M Harmsen RH Segerink FB Prangsma JC Enoch S Kuipers L 《Physical review letters》2006,97(14):146102
The influence of hole shape on the nonlinear optical properties of metallic subwavelength hole arrays is investigated. It is found that the amount of second harmonics generated can be enhanced by changing the hole shape. In part this increase is a direct result of the effect of hole shape on the linear transmission properties. Remarkably, in addition to enhancements that follow directly from the linear properties of the array, we find a hot hole shape. For rectangular holes the effective nonlinear response is enhanced by more than 1 order of magnitude for one particular aspect ratio. This enhancement can be attributed to slow propagation of the fundamental wavelength through the holes which occurs close to the hole cutoff. 相似文献
11.
Optical transmission of a two-dimensional array of subwavelength holes in a metal film has been numerically studied using a differential method. Transmission spectra have been calculated showing a significant increase of the transmission in certain spectral ranges corresponding to the excitation of the surface polariton Bloch waves on a metal surface with a periodic hole structure. Under the enhanced transmission conditions, the near-field distribution of the transmitted light reveals an intensity enhancement greater than 2 orders of magnitude in localized ( approximately 40 nm) spots resulting from the interference of the surface polaritons Bragg scattered by the holes in an array. 相似文献
12.
Zhimin Liu Hongjian Li Haiqing Xu Guangtao Cao Xiuke Xu Hui Yang 《Optics Communications》2012,285(18):3781-3786
We propose an H-shaped metallic grating and investigate its surface plasmon resonance properties. The result shows the formation process of the transmission spectra of the H-shaped grating by adjusting the depths of the arm cuts, and a band gap is formed on the region of short wavelength. It is also presented that the transmission of the H-shaped grating sensitively depends on the width and position of the arm slit, noticeable magnitude modification, redshift and blueshift, meld and split of the resonance peaks are found. In addition, the resonance peaks exhibit dips in the transmission spectrum when the two slit widths are different, and the dips are tunable by changing any one slit width for fixed another slit. To understand its physical origin, a field-interference mechanism, the Fabry–Pérot-like resonance theory and the phase resonance mechanism have been suggested, respectively. By selecting appropriate structural parameters, an H-shaped metallic grating for optical filter and channel selecting devices can be constructed. 相似文献
13.
The monolayer Al2O3:Ag thin films were prepared by magnetron sputtering. The microstructure and optical properties of thin film after annealing
at 700 °C in air were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy,
and spectrophotometer. It revealed that the particle shape, size, and distribution across the film were greatly changed before
and after annealing. The surface plasmon resonance absorption and thermal stability of the film were found to be strongly
dependent on the film thickness, which was believed to be associated with the evolution process of particle diffusion, agglomeration,
and evaporation during annealing at high temperature. When the film thickness was smaller than 90 nm, the film SPR absorption
can be attenuated until extinct with increasing annealing time due to the evaporation of Ag particles. While the film thickness
was larger than 120 nm, the absorption can keep constant even after annealing for 64 h due to the agglomeration of Ag particles.
On the base of film thickness results, the multilayer Al2O3:Ag solar selective thin films were prepared and the thermal stability test illustrated that the solar selectivity of multilayer
films with absorbing layer thickness larger than 120 nm did not degrade after annealing at 500 °C for 70 h in air. It can
be concluded that film thickness is an important factor to control the thermal stability of Al2O3:Ag thin films as high-temperature solar selective absorbers. 相似文献
14.
By means of X-ray diffraction, BET nitrogen adsorption, UV-Vis-NIR transmission spectroscopy, transmission electron microscope, scanning electron microscope, X-ray photoelectron spectroscopy and photodegradation of methylene blue, effects of Ag doping on the microstructure and photocatalytic activity of TiO2 films prepared by sol–gel method were studied. It is found that with a suitable amount (2–4 mol%), the Ag dopant increases the photocatalytic activity of TiO2 films. The mechanism can be attributed to that (1) anatase grain sizes decrease with Ag doping and the specific surface areas of doped TiO2 films increase, the charge transfer in TiO2 films is promoted; (2) by enhancing the electron–hole pairs separation and inhibiting their recombination, the Ag dopant enhances the charge pair separation efficiency for doped TiO2 films. 相似文献
15.
采用化学电沉积方法,通过控制沉积电压,电沉积时间等实验参量,确定出最优实验条件,在冰浴条件下,实验温度范围为0~2 ℃之间,在氧化铟锡导电薄膜表面沉积二维结构随机排列的纳米银树枝,并在银树枝表面涂覆一定厚度的绝缘薄膜聚乙烯醇后,与另外一层银树枝组装制作成银树枝/聚乙烯醇/银树枝复合结构.实验表明,参比样品在可见光波段400~750 nm处没有透射峰的出现,而银树枝/聚乙烯醇/银树枝复合结构在此波段有多个透射通带峰,且在相应波长表现出了聚焦效应. 相似文献
16.
Extraordinary terahertz transmission through subwavelength spindle-like apertures in NbN film
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We studied numerically the temperature dependent extraordinary terahertz transmission through niobium nitride(NbN) film perforated with subwavelength spindle-like apertures. Both the resonant frequency and intensity of extraordinary terahertz transmission peaks can be greatly modified by the transition of NbN film from the normal state to the superconducting state. An enhancement of the(±1, 0) NbN/magnesium oxide(MgO) peak intensity as high as 200% is demonstrated due to the combined contribution of both the superconducting transition and the excitation of localized surface plasmons(LSPs) around the apertures. The extraordinary terahertz transmission through spindle-like hole arrays patterned on the NbN film can pave the way for us to explore novel active tuning devices. 相似文献
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18.
It is shown that photoinduced dichroism in photosensitive AgCl films with Ag granules can be used to record the spectral dependence of the state of polarization specified by anisotropic crystals. The recording of the state of polarization throughout the visible spectral region is favored by the frequency photoadaptation, which is typical of AgCl–Ag films. This effect also determines the good reproduction of color corresponding to the spectrum of the irradiating beam. The results show the feasibility of determining the magnitude of photoinduced dichroism and its dispersion by analyzing the pattern recorded in a film in polarized light. 相似文献
19.
An event horizon for “relativistic” fermionic quasiparticles can be constructed in a thin film of superfluid 3He-A. The quasiparticles see an effective “gravitational” field which is induced by a topological soliton of the order parameter.
Within the soliton the “speed of light” crosses zero and changes sign. When the soliton moves, two planar event horizons (black
hole and white hole) appear, with a curvature singularity between them. Aside from the singularity, the effective spacetime
is incomplete at future and past boundaries, but the quasiparticles cannot escape there because the nonrelativistic corrections
become important as the blueshift grows, yielding “superluminal” trajectories. The question of Hawking radiation from the
moving soliton is discussed but not resolved.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 11, 833–838 (10 December 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
20.
The maximization of the sensitivity of magneto-optical recording media in the short wavelength region is discussed. We show that a combination of the optimized thickness of dielectric and Ag (or CoAg) films can increase the magneto-optic Kerr effect in FeTbCo media by about five times of magnitude in the UV and blue spectral range. It has been shown that the local plasmon excited in the Ag-based films strongly enhances the magneto-optical properties in amorphous FeTbCo magnetic film. The Kerr rotation spectra get the maxima values for the resonance conditions when the local plasmon can be excited in the Ag or CoAg films. 相似文献