Wang Qiao, Chu Shuwen, Yu Li, Gao Huixuan, Peng Wei
Department of Physics, Dalian University of Technology, Ganjingzi District, Dalian 116024, China.
Nanomaterials (Basel). 2019 Oct 6;9(10):1421. doi: 10.3390/nano9101421.
In this paper, we focus on transmission behavior based on the single aperture with a scatter. Both the near-field enhancement and polarization selection can be achieved numerically with a proposed nano-system under He-Ne laser wavelength. The nano-system consists of an Ag antenna, a wafer layer, an Ag film with an aperture and a dielectric substrate. Numerical results show that the near-field enhancement is related to the FP-like resonance base on surface plasmon polaritons (SPPs) in the metal-isolator-metal (MIM) waveguide for transverse magnetic (TM) polarization. The near-field optical spot is confined at the aperture export with a maximal electric intensity 20 times the value of the incident field for an antenna length of 430 nm. The transmission cutoff phenomenon for transverse electric (TE) polarization is because the transmission is forbidden for smaller aperture width. High extinction ratios of 9.6×10-8 (or 70.2 dB) and 4.4×10-8 (or 73.6 dB) with antenna lengths of 130 nm and 430 nm are achieved numerically with the nano-system. The polarization selective property has a good angular tolerance for oblique angles smaller than 15°. The spectral response is also investigated. We further demonstrate that the nano-system is applicable for another incident wavelength of 500 nm. Our investigation may be beneficial for the detection of polar molecules or local nano polarized nanosource.
在本文中，我们聚焦于基于带有散射的单孔径的传输行为。在氦氖激光波长下，通过所提出的纳米系统可以数值实现近场增强和偏振选择。该纳米系统由一个银天线、一个晶圆层、一个带有孔径的银膜和一个介电基板组成。数值结果表明，对于横向磁（TM）偏振，近场增强与基于表面等离激元极化激元（SPPs）在金属 - 绝缘体 - 金属（MIM）波导中的类法布里 - 珀罗（FP）共振有关。对于天线长度为430 nm的情况，近场光斑被限制在孔径出口处，最大电场强度是入射场值的20倍。横向电（TE）偏振的传输截止现象是因为对于较小的孔径宽度，传输是被禁止的。使用该纳米系统，在天线长度为130 nm和430 nm时，数值上分别实现了9.6×10 - 8（或70.2 dB）和4.4×10 - 8（或73.6 dB）的高消光比。对于小于15°的斜角，偏振选择特性具有良好的角度容差。还研究了光谱响应。我们进一步证明该纳米系统适用于500 nm的另一个入射波长。我们的研究可能对极性分子的检测或局部纳米极化纳米源有益。
