内嵌镜像对称矩形腔楔形金属狭缝阵列的宽带增强透射

Broadband Enhanced Transmission through Wedge-shape Metallic Slits Array Embedded with Mirror Symmetric Rectangular Cavities

摘要:

采用时域有限差分法研究了内嵌镜像对称矩形腔长度、宽度及其位置对楔形金属狭缝阵列结构透射特性的影响。研究发现,采用此结构形成的光子晶体结构所产生的能带可以调控禁带,不仅在短波长范围存在明显的传输禁带,而且在长波长范围具有较好的增强透射,表明这种内嵌镜像对称矩形腔进一步破坏了类法布里-珀罗腔共振条件,更有利于短波长范围表面等离激元能量局域在腔内,同时提高长波长范围的透射率。矩形腔位置是影响传输禁带和透射特性的主要因素,其越接近中心位置,禁带越宽,透射率越高;矩形腔厚度主要影响禁带宽度,厚度为140nm时,禁带宽度可达236nm;矩形腔长度主要影响透射特性,长度为260nm时,透射率可达95%。

Abstract:

The effects of length, width and position of embedded mirror symmetric rectangular cavities on transmission property of wedge-shape metallic slits array were studied using the finite-difference time-domain method. The results show that the generated energy band can control forbidden band by formative photonic crystal structure, the structure makes obvious forbidden band of transmission existing in short-wavelength range, and meanwhile it has enhanced transmission in long-wavelength range. It shows that the proposition of embedded with mirror symmetric rectangular cavities further destroys the resonance condition of Fabry-Perot-like cavity. It’s beneficial for energy of surface plasmon polariton to localize in cavity in short-wavelength range, meanwhile it improves the transmittance in long-wavelength range. The position of rectangular cavity is the main factor affecting the forbidden band of transmission and transmission property: when it approaches the central location, the forbidden band is wider and the transmittance is higher. The thickness of rectangular cavity mainly influences the width of forbidden band: when the thickness is 140nm, the width of forbidden band can be 236nm. The length of rectangular cavity influences the transmission property: when the length is 260nm, the transmittance can be 95%.