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

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%。

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 140 nm, the width of forbidden band can be 236 nm. The length of rectangular cavity influences the transmission property： when the length is 260 nm, thetransmittance can be 95 %.