【作者】 闵长俊；

【导师】 明海； 王沛；

【作者基本信息】 中国科学技术大学 ， 光学， 2008， 博士

【摘要】 本论文的研究工作是在国家重点基础研究发展规划项目No.2006CB302905,国家自然科学基金项目No.60736037、No.10474093等项目的资助下完成的。主要运用二维非线性时域有限差分法(FDTD),研究了亚波长金属结构中表面等离子体(Surface Plasmons,SPs)相关调控机理和应用:通过构造不同结构参数,分析了SPs等多种光学模式对亚波长金属结构中异常透射现象的作用机理,提出了金属表面位相是影响光学模式和透射的重要因素;引入非线性效应实现了亚波长金属结构中光束偏折、聚焦、分束等现象的动态调控;研究了非线性光学材料复合亚波长金属结构的光学双稳态特性,设计了一个基于光学双稳态的亚波长高速全光开关结构。本论文主要的研究工作和成果如下:1.结合二维时域有限差分法数值模拟软件,通过构造不同结构参数,研究了SPs、复合衍射衰逝波(CDEW)、腔模(CM)等多种光学模式对亚波长金属结构中透射增强和削弱现象的影响,分析了它们各自不同的作用机理,明确了结构参数对这些光学模式的影响和对远场透射的调控规律,提出了金属表面位相是影响光学模式和透射的重要因素。利用结构参数对SPs的调控,实现了亚波长结构中光束单向透过的功能,得到了47.83dB的最大消光比,在光信号的通讯和处理等方面有重要的应用前景。2.运用非线性时域有限差分法数值模拟软件,研究了与非线性光学材料复合的亚波长金属结构中,三阶非线性光学效应的引入对SPs色散关系、激发、耦合、传播等物理过程的影响。通过结构设计和优化,实现了对光束偏折、聚焦、分束等现象的动态调控,得到了较大范围的的偏折角度调控(偏折角8°-24°)和焦点位置调控(调控范围在1μm以上),在近场探测与光刻、SPs天线扫描、纳米集成光学等领域都有广阔的应用前景。3.研究了非线性材料复合亚波长金属结构的光学双稳态效应,探索了非线性材料厚度、光栅狭缝宽度等结构参数对远场透射和双稳态效果的影响,运用SPs特性和金属波导理论分析了其中的物理机理。在此基础上设计了一个基于光学双稳态的高速亚波长全光开关结构,研究了该开关结构的远场透射、双稳态和时间响应特性,得到了0.2ps的最快开关时间。本论文的创新点主要包括:1.通过构造不同亚波长金属结构,研究了SPs、CDEW、CM等不同光学模式在异常透射现象中各自不同的作用机理,提出了金属表面位相是影响光学模式和透射的重要因素。实现了亚波长结构中光束单向透过的功能,得到了47.83dB的最大消光比。2.通过引入三阶非线性效应,实现了对亚波长金属结构中光束偏折、聚焦、分束等现象的动态调控,研究了相关的调控机理和调控手段,得到了较大的调控范围和明显的调控效果。3.利用非线性FDTD方法研究了非线性光学材料复合亚波长金属结构的光学双稳态特性,并由此设计了一个亚波长高速全光开关结构,得到了0.2ps的最快开关时间。更多还原

【Abstract】 The research work within this dissertation is supported by the National Key Basic Research Program of China(No.2006CB302905),the Key Program of National Natural Science Foundation of China(No.60736037),the National Natural Science Foundation of China(No.10474093)and so on.By using the two dimensional nonlinear finite difference time domain(FDTD)method,the roles of surface plasmons(SPs)and other optical modes in extraordinary optical transmission(EOT) are analyzed,beam deflection and focusing controlled by nonlinear optical effect are studied in micro-and nano-metallic structures containing nonlinear materials.Optical bistability is also numerically investigated in subwavelength metallic structures,and an ultrafast all-optical switching structure is designed and studied with a switching time of picosecond’s level.The main research works and conclusions are as following:1.Based on two-dimensional FDTD method,the roles of SPs,Composite Diffracted Evanescent Wave(CDEW)and Cavity Mode(CM)are analyzed and distinguished in EOT of subwavelength metallic structures.The influences of structure parameters on these optical modes and far-field transmission are studied.By controlling the structure parameters,a single-pass transmission effect is achieved in subwavelength metallic structures with a maximal extinction ratio of 47.83dB.2.Based on nonlinear FDTD method,the influence of 3rd nonlinear effect is investigated on excitation,coupling,transmission and dispersive relation of SPs in micro-and nano-metallic structures containing nonlinear materials.The dynamic control of beam deflection,focusing and splitting is studied by modulating incident light.Large modulating ranges of deflection angle(8°～24°) and focusing distance(＞1μm)are achieved,which will offer great applications in near-field optics,SPs antenna and nano-integrate optics etc. 3.Optical bistability is numerically investigated in a subwavelength metallic grating coated by nonlinear material.The influences of structure parameters, such as thickness of nonlinear material and slit width of metallic grating,are studied on far-field transmission and bistability.The physical mechanism in the structure is analyzed by SPs and optical waveguide theory.Based on optical bistability,an ultrafast all-optical switching structure is designed with metal-dielectric composite nonlinear materials.The characters of far-field transmission,bistability and response time of the switching are studied and a shortest switching time of 0.2ps is achieved.Highlights of the dissertation are as following:1.The roles of SPs,CDEW and CM are analyzed and distinguished in EOT of subwavelength metallic structures.A single-pass transmission effect is achieved in subwavelength metallic structures with a maximal extinction ratio of 47.83dB.2.The dynamic controls of beam deflection,focusing and splitting is numerically studied for the first time in micro-and nano-metallic structures containing nonlinear materials.Large modulating ranges of deflection angle(8°～24°)and focusing distance(＞1μm)are achieved by nonlinear FDTD method.3.Optical bistability is numerically investigated in a subwavelength metallic grating coated by nonlinear material for the first time.An ultrafast all-optical switching structure based on bistability is designed with a shortest switching time of 0.2ps.更多还原