Ag纳米孔阵列中的表面等离子体特性及其相关光学性能

Characteristics of Surface Plasmon Resonance in Ag Nanohole Arrays and Its Related Optical Properties

Ag纳米孔阵列因为反常光学透射现象而在基础研究领域和应用研究领域受到广泛关注。目前有关金属孔阵列结构EOT现象的起因还没有得出一个完整清晰的物理机制,这是由于金属孔阵列中存在着复杂的表面等离子体特性。论文基于时域有限差分技术,采用FDTD Solutions软件对Ag纳米孔阵列的光学性能与孔的形状、孔阵列的周期以及薄膜厚度间的关系进行了仿真研究,并对光学现象背后的物理机制——Ag纳米孔阵列中的表面等离子体耦合特性进行了仿真分析。研究结果表明:局域表面等离子体共振和表面等离子体激元间的耦合将会对Ag纳米孔阵列的光学性质产生重要的影响,其中孔形对局域表面等离子体共振和表面等离子体激元间的耦合影响巨大。Ag矩形纳米孔阵列展现出了有趣的光学行为:上、下表面金属表面等离子体激元间的反对称耦合模式,以及靠近矩形纳米孔两长边的局域表面等离子体共振间的反对称耦合模式分别被激发了。

Ag nanohole arrays have received widely attention in the field of fundamental research and applied research due to the phenomenon of extraordinary optical transmission.However,at present the origin of the phenomenon of extraordinary optical transmission(EOT)is not fully understood as the characteristics of surface plasmon resonance in the metal hole arrays are intricate.In this paper,the dependence of optical properties on the hole shape,period of nanohole arrays and metal film thickness,in Ag nanohole arrays are investigated using the finite difference time domain technique.The physical mechanism behind the light phenomena is discussed:the coupling between localized plasmon resonances and surface plasmon polaritons is found to play an important role on the optical properties,while the hole shape played a crucial role on the coupling mechanism.Interesting light phenomena are observed in Ag films perforated with rectangle nanohole arrays:the antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane,and the antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole are excited in it respectively.