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提出了一种X-两环的金属周期性阵列结构,该结构由两个同心圆环包围中心X型构成.利用时域有限差分算法研究了该结构的光学特性.计算表明,当光入射到金属表面时,能够在结构中产生法诺共振现象,并在不同的位置下产生共振谷.同时,共振谷的出现又明显依赖于结构的相对参数(X的臂长、内外环的距离、内外环宽度、周期、环数、X所呈的角度),从而可以通过调节结构的相对参数来实现对结构的共振强度及共振谷位置的调控.另外,进一步分析了在不同环境折射率条件下该结构共振谷的变化规律,可以得出该结构也对周围的环境折射率有着较高的敏感度,最高可达1300 nm/RIU.结果表明,该结构在环境折射率传感器及某些光子器件的应用方面有着潜在的价值. 相似文献
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利用自下而上的纳米加工工艺,制备了一种由银纳米线对和金膜构成的等离激元法布里珀罗(F-P)腔。暗场散射光谱和数值模拟表明,金膜表面传输的表面等离激元经银纳米线对的多次反射下,会在腔内形成驻波现象,并在散射光谱中呈现出多光束干涉调制的光谱线型。利用这一原理设计一个折射率测量实验,通过测量不同浓度甘油溶液的折射率,得到了F-P腔共振波长随溶液折射率增大的线性红移规律。进而通过调谐F-P腔的长度,得到该F-P腔最高的探测灵敏度为555 nm/RIU。 相似文献
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基于波导光栅共振原理和古斯-汉欣(Goos-Hänchen)位移理论,提出一种表面覆膜波导光栅传感结构,并研究其共振光谱特性。通过在光栅表面涂覆低折射率聚合物功能膜层优化其共振光谱特性,选用多孔硅作为待测物承载单元,可以使光学探针更充分地接触待测样本,从而提高其检测性能。根据波导光栅共振相位条件,建立了共振波长和样本折射率之间的数学模型,通过检测共振位置的改变进而对样本浓度进行检测。研究表明,该表面覆膜波导光栅传感结构具有线型对称和窄线宽的共振光谱特性,可实现高品质因数(Q值)和高灵敏度的传感特性,其Q值为1 488,对折射率的检测极限可达5×10-4 RIU(RIU为折射率单位)。通过检测不同浓度的葡萄糖溶液对其传感特性进行验证分析,结果表明,共振波长与葡萄糖溶液浓度之间具有良好的线性关系,对葡萄糖溶液的检测灵敏度为1.12nm/1%,证明了该表面覆膜波导光栅传感结构的有效性,可以用于对低浓度样本溶液的实时动态监测,并为波长调制型光学折射率传感器的研究提供理论指导。 相似文献
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设计了一种基于金属-介质-金属波导的半圆形谐振腔与矩形谐振腔的耦合结构,采用有限元方法研究了该结构的传播特性.结果表明:透射光谱中产生一个类似Fano共振线型的共振谷,该Fano共振由半圆形谐振腔的宽谱共振和矩形谐振腔的窄谱共振相互耦合所导致.变化谐振腔的结构参量,发现该Fano共振谷位置依赖于矩形谐振腔的几何参量,而对两谐振腔相对位置的微小移动不敏感;同时,改变两谐振腔的并联方式,研究了两种衍生结构的传播特性,发现这些结构均可产生明显的Fano共振.此外,通过在谐振腔中填充不同折射率的介质材料,研究了三种结构基于Fano共振效应的折射率传感特性,其折射率敏感度最高达到750 nm/RIU.研究结果可为未来芯片上基于表面等离极化激元波导的高灵敏折射率传感器的设计提供理论依据. 相似文献
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为了实现被测折射率范围可调,提高检测灵敏度,将双波长差分检测技术应用于平面波导激励的金属-介质-金属组成的对称型表面等离子体共振传感结构中.通过对对称结构的模式特性分析,研究了该结构中激发等离子体表面波时,介质厚度与被测折射率的关系及双波长差分检测的原理.采用离子交换法制备平面波导,用费米函数拟合其渐变折射率分布.用光强调制方式,分别进行单波长和双波长差分检测,对折射率为1.33~1.428之间的甘油溶液进行测试,实验结果表明,该结构可激发等离子体表面波,与传统平面波导激励的表面等离子体共振传感结构相比,通过改变被测介质的厚度可以改变共振条件,进而改变折射率的测量范围.若被测范围选择合适,检测的线性较好,采用差分检测方法比单波长检测方法的灵敏度提高近一倍. 相似文献
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表面等离子体共振(SPR)光学传感器能实现生物医学的快速、 无标记、 高精度检测,是生物化学分析的重要方法。 研制了基于波长调制型的Kretschmann结构表面等离子体共振(SPR)生物传感系统,研究了在体溶液传感方式下的传感性能。 利用不同浓度的乙醇和乙二醇溶液进行体溶液传感测试。 实验结果表明,在折射率低时共振波长对折射率变化响应的灵敏度低,但响应的线性度高;随着折射率增大,共振波长对折射率的响应变化的灵敏度提高。 在1.407 0~1.430 RIU折射率范围内,灵敏度高达11 487 nm·RIU-1。 传感器的共振波长的稳定性为0.213 8 nm,可分辨最小折射率趋近10-6 RIU。 所研制的波长调制型表面等离子共振传感器操作简单、 灵敏度高、 检测范围大,可实现浓度极低生物标记物的有效检测,在化学、 生物传感领域有重要的应用。 相似文献
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利用传输矩阵方法,模拟研究了FC(N)准晶链排列的多层介质膜中存在不同缺陷情形时,光在其中传播的透射规律.结果表明,当Fibonacci准晶中存在缺陷时,引入了缺陷模,而且其缺陷模具有与自身结构相关的特点.还进一步模拟研究了存在负折射率吸收缺陷媒质时的FC(N)准晶链的透射系数,出现了共振透射率大于1的情形.同时还研究了负折射率缺陷媒质的虚部对禁带中共振透射峰大小的影响,发现并不是所有引入负折射率吸收缺陷媒质的准晶都会出现共振透射率大于1的现象. 相似文献
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The effect of an anti-hydrogen bond on Fermi resonance:A Raman spectroscopic study of the Fermi doublet ν1-ν12 of liquid pyridine 下载免费PDF全文
The effects of an anti-hydrogen bond on the ν1-ν12 Fermi resonance(FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy.Three systems,pyridine/water,pyridine/formamide,and pyridine/carbon tetrachloride,provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex.Water forms a stronger anti-hydrogen bond with pyridine than with formamide,and in the case of adding non-polar solvent carbon tetrachloride,which is neither a hydrogen bond donor nor an acceptor and incapable of forming a hydrogen bond with pyridine,the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce.The dilution studies are performed on the three systems.Comparing with the values of the Fermi coupling coefficient W of the ring breathing mode ν1 and triangle mode ν12 of pyridine at different volume concentrations,which are calculated according to the Bertran equations,in three systems,we find that the solution with the strongest anti-hydrogen bond,water,shows the fastest change in the ν1-ν12 Fermi coupling coefficient W with the volume concentration varying,followed by the formamide and carbon tetrachloride solutions.These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the ν1-ν12 FR of pyridine.According to the mechanism of the formation of an anti-hydrogen bond in the complexes and the FR theory,a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the ν1-ν12 FR of pyridine is given. 相似文献
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We report on a new time-resolved coherent Raman technique that is based on the generation of thermal gratings following a population change among molecular levels that is induced by stimulated Raman pumping. This is achieved by use of spatially and temporally overlapping intensity interference patterns generated independently by two lasers. When this technique is used in carbon dioxide, making use of transitions that belong to the Q branches of the v(1)/2v Fermi dyad, it is possible to investigate molecular energy transfer processes. A further unique feature of this method is spectral resolution that is better than that achieved by coherent anti-Stokes Raman scattering. 相似文献
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Wang D Buixaderas E Íñiguez J Weerasinghe J Wang H Bellaiche L 《Physical review letters》2011,107(17):175502
We have used first-principles-based simulations and Raman scattering techniques to reveal a novel dynamical phenomenon in Pb(Zr,Ti)O(3) solid solutions: a Fermi resonance (FR) emerging from the nonlinear coupling between ferroelectric (FE) motions and tiltings of oxygen octahedra. This FR manifests itself as the doubling of a nominally single FE mode in a purely FE phase, when the resonant frequency of the FE mode is close to the first overtone of the tiltings. We show that the FR is the result of a nonlinear coupling that is proportional to the spontaneous polarization of the material and derive an analytical model that captures the essence of the effect. 相似文献
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It is well known that scattering of a polychromatic plane wave by a random medium, i.e., by a medium whose refractive index varies randomly with position, may produce frequency shifts of spectral lines. It has been a common perception that a random medium is required for generation of such spectral shifts by scattering. In this Letter we show that such a phenomenon occurs even when the refractive index of the medium is a deterministic function of position. We also show that this phenomenon may be used to obtain information about the structure of a deterministic medium. 相似文献
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N. V. Tcherniega A. D. Kudryavtseva 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(4):513-518
The results of the experimental study of nonlinear-optical effects in photonic crystals, i.e., synthetic opal matrices and nanocomposites (matrices with voids filled with different nonlinear liquids) are presented. The following nonlinear-optical effects were observed under experimental conditions: the photonic flame effect (PFE), stimulated globular scattering (SGS), and stimulated Raman scattering (SRS). The dependence of these effects on the excitation conditions, nanocomposite refractive index contrast, and sample temperature was studied. PFE lines were detected in the Stokes spectral region. SGS spectra at the temperature of liquid nitrogen were studied. 相似文献
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H. Dicko O. Pags R. Hajj Hussein G. K. Pradhan C. Narayana F. Firszt A. Marasek W. Paszkowicz A. Maillard C. Jobard L. Broch F. El Hajj Hassan 《Journal of Raman spectroscopy : JRS》2016,47(3):357-367
The apparently universal 1‐bond → 2‐mode percolation behavior in the Raman spectra of zincblende semiconductor alloys is generally observed for the short bond only, and not for the long one. In this work we perform a combined high‐pressure‐backward/near‐forward Raman study of the leading percolation‐type (Zn,Be)Se alloy (~50 at.% Be), which exhibits a distinct percolation doublet in the spectral range of its short Be―Se bond, in search of a Zn―Se analogue. The high‐pressure‐backward insight is not conclusive per se, but clarifies the perspective behind the near‐forward Raman study. The latter reveals an unique Zn―Se phonon–polariton. Its fair contour modeling depending on the scattering angle is achieved within the linear dielectric approach, based on ellipsometry measurement of the ZnBeSe refractive index. Somewhat surprisingly this reveals that the phonon–polariton in question is a ‘fractional’ one in that it carries only half of the available Zn―Se oscillator strength, as ideally expected in case of a BeSe‐like bimodal Raman behavior of the long Zn―Se bond. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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The Fermi resonance behaviours of the two groups of binary solutions --- pyridine and methanol, benzene and carbon tetrachloride, under different pressures are investigated according to their Raman spectra. The effect of pressure on Fermi resonance in binary solution differs significantly from that in pure liquid. In a binary solution, with the intermolecular distance shortening, the intermolecular interaction potential increases, the shift rates of the Raman spectral lines increase, the spectral line splitting occurs ahead of that in pure liquid, and the wavenumber separation Δ0 between the unperturbed harmonic levels shifts more quickly, too. The Fermi resonance parameters, the coupling coefficient W and the intensity ratio R of the two Raman bands, decrease rapidly with pressure increasing, and the pressure at which Fermi resonance phenomenon disappears is much lower than that in pure liquid, especially in the solution whose molecules are of the same polarity. This article is valuable in the identification and the assignment of spectral lines under high pressure, as well as the study of high pressure effect, intermolecular interaction, and solvent effects in different cases, etc. 相似文献
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V. G. Kravets 《Optics and Spectroscopy》2013,114(2):230-235
The photoluminescence, IR transmission, and Raman scattering spectra of nc-Si nanocrystals (5 nm in size) have been investigated. The shape and spectral position of maxima in the photoluminescence and IR transmission spectra are theoretically described. It is shown that nc-Si particles consist of a Si core and a SiO2 shell. The existence of surface Si-O and Si-H states in Si nanocrystals enhances photoluminescence. It is established that the spectral position of the main Raman scattering peak in the frequency range 500–520 cm?1 undergoes a significant red shift for small-size nanostructures. Based on direct determination of the complex refractive index of n-Si nanoparticles by measuring spectral ellipsometric parameters, nanostructured silicon is found to be an indirect-gap semiconductor. 相似文献