干涉型表面等离激元显微术成像的研究

运用Matlab系统地模拟了信号光相位与样品的厚度和折射率之间的对应关系,为干涉型表面等离激元显微术提供了理论依据,同时证明了基于相位探测的干涉型表面等离激元显微术相比基于强度探测的表面等离激元显微术具有更高的纵向分辨率,而且为生物化学方面的动态变换过程的实时监测提供了一种新方法.     

The surface ace plasmon resonance effect in holography

A hologram has been made using a surface plasmon resonance wave as the reference beam. The surface wave was stimulated on a 1200-line/mm aluminum reflection grating that was coated with a thin layer of high resolution photographic emulsion. Experimental results are presented.     

Optical modulator based on acousto-plasmonic coupling

A possibility of increasing efficiency of acousto-optic interaction at a wavelength of 10.6 μm by surface plasmon polaritons is investigated. The diffraction of a surface plasmon polariton (excited by a volume beam) on a surface acoustic wave is analyzed and numerically simulated.     

Sensitivity enhancement based on application of multi-pass interferometry in phase-sensitive surface plasmon resonance biosensor

A novel design of multi-pass surface plasmon resonance (SPR) biosensor with differential phase interrogation based on multi-pass interferometry is presented. This new configuration provides an intrinsic phase amplification effect of over twofold by placing the SPR sensor head in a signal arm of the interferometer so that the interrogating optical beam will traverse the sensor surface infinite number of times. Experimental interferometers based on the Michelson and Fabry–Perot configurations have been employed to experimentally verify this amplification effect when they were compared with Mach–Zehnder configuration, results obtained from salt–water mixtures, antibody–antigen, and protein–DNA binding reaction confirmed the expected phase measurement enhancement, thus leading to the possibility of direct detection of small sized bio-molecules using SPR.     

金膜上亚波长小孔阵列表面等离激元颜色滤波器偏振性质

金属薄膜上制备的表面等离激元颜色滤波器具有很强的颜色可调性. 在200 nm厚的金膜上, 通过聚焦离子束刻蚀, 制备一系列周期逐渐变化的圆形、方形、矩形亚波长尺寸小孔方阵列表面等离激元颜色滤波器, 改变入射光的偏振方向, 观察其超透射滤波现象. 研究发现: 对于矩形小孔阵列, 其透射光颜色随入射光偏振方向的变化而改变; 而对于圆形、方形的小孔阵列, 其透射光颜色对入射光的偏振方向并不敏感. 分析表明, 对于金膜上刻蚀的小孔结构, 虽然结构的周期性导致的表面等离激元极化子会对透射光的颜色变化产生一定影响, 但是随小孔形状变化的局域表面等离激元共振才是影响透射光颜色的决定性因素. 如果入射光没有在小孔中激发出局域表面等离激元, 则表面等离激元极化子对透射光的影响也会消失. 根据不同形状小孔周期结构透射光颜色随入射光的偏振变化特点, 制备出了包含两种小孔形状的复合周期结构. 随着入射光偏振方向的改变, 该结构会显示出不同的颜色图案. 关键词： 表面等离激元极化子 局域表面等离激元 颜色滤波器 亚波长小孔阵列     

Design of terahertz beam splitter based on surface plasmon resonance transition

According to the resonance transition between propagating surface plasmon and localized surface plasmon, we demonstrate a design of beam splitter that can split terahertz wave beams in a relatively broad frequency range. The transmission properties of the beam splitter are analyzed utilizing the finite element method. The resonance transition between two kinds of plasmons can be explained by a model of coherent electron cloud displacement.     

Plasmonic Airy beam generated by in-plane diffraction

We report an experimental realization of a plasmonic Airy beam, which is generated thoroughly on a silver surface. With a carefully designed nanoarray structure, such Airy beams come into being from an in-plane propagating surface plasmon polariton wave, exhibiting nonspreading, self-bending, and self-healing properties. Besides, a new phase-tuning method based on nonperfectly matched diffraction processes is proposed to generate and modulate the beam almost at will. This unique plasmonic Airy beam as well as the generation method would significantly promote the evolutions in in-plane surface plasmon polariton manipulations and indicate potential applications in lab-on-chip photonic integrations.     

Phase‐controlled directional switching of surface plasmon polaritons via beam interference

A novel method for switching the direction of surface plasmon polarition (SPP) launching is proposed. The principle behind the switching mechanism is based on the relative phase difference between the reference beam and the control beam. Selective guidance of the direction of SPP can be explained by the composition of the charge parity that is induced near the slit edge, which is caused by interference created by two incident beams. The switching of SPP launching direction could be implemented by simple phase modulation of the control beam when the slit parameters satisfy the specific conditions at the designed specific wavelength. An experimental demonstration, in good agreement with numerical results, shows that our configuration of SPP switching can be operated by a quite simple interaction.     

Improving the sensitivity of fiber-optic SPR sensor via radially polarized beam excitation

We study the sensing properties of an intensity-modulated fiber-optic surface plasmon resonance （SPR） sensor using radially polarized beam （RPB）. Because of the rotational symmetry of fiber and RPB, surface plasmon can be excited more efficiently at the sensor surface, which results in an obvious improvement of the sensitivity. Our experiments demonstrate that the sensitivity in the case of RPB illumination is three times higher than that of linearlv polarized beam illumination.     

Terahertz radiation from interaction between an electron beam and a planar surface plasmon structure

The possibility of an electron beam exciting surface plasmons in conducting metal is discussed in this paper. A planar perfect-structure with subwavelength holes is proposed. The phenomenon that mimicking surface plasmon waves can be excited and amplified by an electron beam is proved theoretically and numerically. The mechanism of transmission through a subwavelength hole array is exploited to enhance the interaction between the electron beam and the mimicking surface plasmons.     

氧化钛薄膜调控金属铜的表面等离子体共振特性研究

提出了一种利用氧化钛薄膜对金属铜薄膜表面等离子体共振特性调制的想法。实验中首先使用电子束蒸发制备一批同等厚度的氧化钛薄膜,再利用磁控溅射方法在氧化钛薄膜上沉积厚度为5～80 nm不等的金属铜薄膜。测试结果表明,氧化钛膜层对不同厚度的金属铜薄膜表面等离子体共振增强具有不同调制效果,金属铜薄膜厚度小于20 nm时,底层的氧化钛薄膜对Cu薄膜表面等离子体共振增强效果显著,且随着金属Cu膜层厚度增加表面等离子体共振峰发生蓝移,而当金属铜膜层的厚度超过20 nm时,共振增强效果因金属Cu薄膜消光能力的上升而开始减弱。     

Surface plasmon interference excited by tightly focused laser beams

We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.     

Enhanced backward scattering by surface plasmons on silver film

Surface plasmon and its potential application in nanotechnology have attracted a remarkable amount of attention recently due to their novel properties. In this work we present an angularly resolved surface plasmon scattering study on a primitive metal surface. Using a reversed attenuated total reflection (RATR) setup in the experiment, we obtained a double-crescent shaped and enhanced scattering pattern at far field. The scattering pattern as a function on the variation of angle and polarization of incident beam are studied. Both theoretical and experimental results reveal an enhanced backward scattering by surface plasmon excitation. Consequently, it is shown that this angularly resolved surface plasmon scattering measurement can be employed for resolving a richness of nanoscale surface textures. PACS 42.79.-e; 42.30.Wb; 78.20.Ci     

数值模拟探针诱导表面等离子体共振耦合纳米光刻

采用有损耗介质和色散介质的二维时域有限差分方法,数值模拟了以光波长514.5nm的p偏振基模高斯光束为入射光源,激发Kretschmann型表面等离子体共振,并通过探针的局域场增强效应实现纳米光刻的新方法——探针诱导表面等离子体共振耦合纳米光刻.分别就探针与记录层的间距以及探针针尖大小,模拟分析了不同情况下探针的局域场增强效应和记录层表面的相对电场强度振幅分布.结果表明,探针工作在接触模式时,探针的局域场增强效应最明显,记录层表面的相对电场强度振幅的对比度最大;当探针针尖距记录层5nm时,针尖下方记录层表面的相对电场强度振幅大于光刻临界值的分布宽度与针尖尺寸相近. 关键词： 纳米光刻 表面等离子体共振 时域有限差分方法     

Evanescent Bessel beam generation via surface plasmon resonance excitation by a radially polarized beam

A simple setup for generating evanescent Bessel beams is proposed. When a radially polarized beam is strongly focused onto a dielectric-metal interface, the entire beam is p-polarized with respect to the dielectric-metal interface, enabling excitation of surface plasmons from all directions. The angular selectivity of surface plasmon excitation mimics the function of an axicon, leading to an evanescent nondiffracting Bessel beam. The created evanescent Bessel beam may be used as a virtual probe for near-field optical imaging and sensing applications.     

电子束诱导的纳米颗粒表面等离激元激发模拟

本文基于离散偶极子近似方法,发展出了一套计算任意纳米结构材料的电子能量损失谱的方法和程序. 模拟了在单个银纳米颗粒附近不同入射位置下的电子能量损失谱,其计算结果与实验能谱非常吻合. 虽然离散偶极子近似法早在很多年前就已经被应用到处理外加光场激发的情形,但这套方法才真正提供了一个研究电子束诱导金属纳米颗粒局域表面等离激元激发的计算工具.     

Numerical analysis of waveguide-enhanced optical bistability

We present the results of a simulation study of a multilayer structure for which strongly enhanced (resonant) electric fields are produced at the surface of, and in the interior of, a planar waveguide which is evanescently coupled to an incoming beam in a prism geometry. The resulting field enhancements can far exceed those associated with the well-known surface plasmon resonance in a typical silver film excited in the conventional attenuated total reflection geometry. Simulations are performed for optical bistability for the case of a typical YAG laser beam coupled to a zinc oxide (ZnO) waveguide, demonstrating that the effect should occur for reasonable values of the parameters involved.     

Marangoni forces created by surface plasmon decay

We present optical microfluidic manipulation of silicone oil and glycerol via surface tension driven forces sustained by surface plasmon deexcitation energy. The phonon energy associated with the decaying optically excited surface plasmons in a thin gold foil creates thermal gradients capable of actuating fluid flows. Spectral dependence of the plasmon decay length and control of optical beam characteristics are shown to provide a means for further manipulation.     

Surface plasmon resonance polarizator for biosensing and imaging

A novel polarization-sensitive surface plasmon resonance (SPR) biosensing/imaging scheme is proposed. The scheme uses a periodical spatial phase modulation of the pumping beam of a mixed polarization in the Kretschmann–Raether geometry and takes advantage of SPR-based polarizing effect to drastically absorb p-polarized component changing the resulting polarization state of the beam. The scheme then uses Fourier Transformation to efficiently treat and filter spatially-modulated polarization-sensitive signals and thus to extract and process selected SPR-based response. This approach offers a much higher accuracy of measurements in SPR-based multi-sensing and remote sensing.     

基于表面等离子体激元共振的飞秒抽运探测技术研究

对基于表面等离子体激元共振（SPR）的飞秒抽运探测技术进行了系统地数字分析.计算结果表明,利用SPR技术可将飞秒抽运探测信号强度ΔR/R提高2—3个数量级,其提高的比例依赖于金属膜的厚度和探测光的入射角,其中R和ΔR分别为探测光反射率的总量和变化量.特别地,对于金属-吸收介质体系,金属膜的介电常数变化对ΔR的影响仅为吸收介质影响的2%,所以ΔR/R主要反应吸收介质中的动力学过程,因此该技术对研究表面和界面的超 关键词： 超快光学 表面等离子体共振 飞秒抽运探测技术 信号强度