【作者】 王跃科；

【导师】 魏台辉； 宋瑛林；

【作者基本信息】 哈尔滨工业大学 ， 光学， 2010， 博士

【摘要】 在本论文中,我们研究了两种单向性很好的表面等离子体激元(Surface Plasmon Polartions, SPPs)激发源,以及一种表面等离子体波导的分束器。提出了传统衍射光学中的离散塔尔博特(Talbot)效应在表面等离子体亚波长光学中的类比。研究了两种金属微纳结构的透射特性。首先,提出了一种基于单缝腔天线结构的定向SPPs激发源。通过改变两个金属膜之间的中心距离,可以调节SPPs激发的方向和强度,使其周期性的变化。变化周期利用法布里-珀罗(Fabry-Perot, F-P)干涉理论得到了很好的解释。通过选择合适的参数,最大的分束比可以达到24。因此,该结构可以作为单向性很好的SPPs激发源。并且发现狭缝的长度只影响SPPs的激发强度,对SPPs的分束比没有影响。提出了一种基于双缝腔天线结构的定向SPPs激发源。与单缝腔天线结构相比,其定向激发特性更好(最大分束比提高一个数量级);由于透过面的表面没有微结构修饰,其噪声小。两种定向SPPs激发源都具有可调性,单向性好,分束比周期性变化等特点。提出了一种含有节点腔的T型金属-绝缘体-金属(Metal-Insulator-Metal, MIM)波导,可以用其操控SPPs在波导中的传播。SPPs分束比可以随着节点腔位置的改变而呈现周期性变化。当分束比达到最大(或最小)时,可以利用其作为在SPPs波导中的定向激发器件。我们利用散射矩阵理论很好的解释了有限时域差分法(Finite-Difference Time-Domain, FDTD)数值计算的结果。提出了在亚波长金属波导阵列中存在的离散表面等离子体Talbot效应。与连续的表面等离子体Talbot效应相比,其Talbot自成像效应与入射场的周期性分布无关。Talbot距离可以缩小至亚波长尺寸。Talbot距离可以通过调节金属膜厚度和波导腔宽度而改变。极短的Talbot距离可以达到三分之一入射波长,这是由于相邻波导腔中表面等离子体之间的强耦合造成的。利用FDTD方法数值计算了亚波长金属腔阵列和含有凹槽修饰的狭缝阵列的透射特性。我们发现对于亚波长金属腔阵列,其透过峰是由F-P共振产生;透过谷是由于SPPs共振产生。对于复合的亚波长金属腔阵列,其透过峰会随着相邻腔之间距离的增加而产生红移,这是由于相邻腔之间的耦合减弱造成的。我们发现了对于含有凹槽修饰的狭缝阵列,其透过峰随着凹槽位置的变化而产生周期性的震荡。基于传输线理论的传输矩阵可以很好的解释透过谱的变化规律。更多还原

【Abstract】 In this dissertation, we study the two kinds of therotical model for unidirectional excitation of the Surface Plasmon Polartions(SPPs), and a kind of surface plasmon polatitons waveguide splitter. We propose the plasmonic analogy of the discrete Talbot effect in the traditional diffractive optics. We study the transmission characters of two kinds of metallic nano-structure.First, we propose a kind of unidirectional SPPs source based on the single-slit cavity antenna structure. By tuning the central distance between the two metallic films, the excitation intensity and period vary periodically. The period can be explained very well by the theory of Fabry-perot interference. By choosing the suitable parameters, the maximum splitting ratio reaches 24. Thus, this structure can be used as a well unidirectional SPPs source. In addition,we propose another kind of unidirectional SPPs source based on the two-slits cavity antenna structure. Compared with the single-slit cavity antenna structure, its unidirectional excitation is better (the maximum splitting ratio is one order larger than the previous one). Because there is no nano-structre on the transsmion surface, its noise is low. Both of the two SPPs source possess adjustability, good unidirectional and periodical changes for SPPs splitting ratio.Second, we propose a T-shaped metal-insulator-metal (MIM) plasmonic waveguide with a joint cavity, which can manipulate the propagation of SPPs in waveguide. It is found that the SPPs splitting ratio changes periodically as the joint cavity is moved. When the splitting ratio reaches the maximum(or the mimimum), it can be used as a unidirectional excitation device in the plasmonic waveguide. We utilize the scattering matrix to explain the Finite-Difference Time-Domain(FDTD) results well.Third, we propose the discrete SPPs Talbot effect in the subwavelength metal waveguide arrays. Compared with the continuous SPPs Talbot effect, its self-imaging effect has nothing to do with the input period. The Talbot distance can be reduced to subwavelength size. The Talbot distance can be tuned by the thickness of the metallic film and the width of the waveguide. The ultra-short Talbot distance can be reduced to one third of the incident, which is due to the strong coupling between the SPPs in the adjacent waveguides.We calculate the transsmion charators of the subwavelength metallic cavity arrays and slit arrays with single cut by FDTD. For the subwavelength metallic cavity arrays, the transmission peaks originate from the F-P resonance; and the transmission dips originate SPPs resonance. For the compound subwavelength metallic cavity arrays, the transsmion peaks redshift with the increase of the distance between the neighbour cavities. For the subwavelength slit arrays with single cut, the transmission peaks changes with the cut position periodically. The law of the transmission variation can be explained by the transmission line theory very well更多还原