Enhanced optical transmission through double-layer gold slit arrays

• Published in: Chinese physics B 2010-07, Vol.19 (7), p.570-575
• Main Author: 谢素霞 李宏建 周昕 徐海清 付少丽
• Format: Article
• Language: English
• Subjects: Arrays; Electric fields; Energy distribution; Finite difference method; Gold; Plasmons; Slits; Waveguides; 光传输; 共振模式; 共振透射; 有限差分时域法; 表面等离子体
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/19/7/077803

We investigate the relationship between the transmission and the layer distance of double-layer gold slit arrays by using the finite-difference time-domain method. The results show that the transmission properties can be influenced strongly by layer distance. We attribute the two types of resonant modes to surface plasmon resonance and the localised waveguide resonance. We find that the localised waveguide transmission peak redshifts and becomes broader with increasing layer distance D. We also describe and explain the splitting, shift, and degeneration of the surface plasmon resonant transmission peak theoretically. In addition, to clarify the physical mechanism of the transmission behaviours, we analyse the distributions of electric field and total energy for the three transmission peaks with distance D = 45 nm for the double-layer system. Light transporting behaviours are mostly concentrated in the region of the slits as well as the interspaces of the two layers, and for different resonant wavelengths the electric field and energy distributions are different. It is expected that the results obtained here will be helpful for designing subwavelength metallic grating devices.