Spoof Surface Plasmon Polaritons in Multiscale Microstructured Slot Waveguide

Zhang Qiang College of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, Guangdong, China Xiang Hong Department of Applied Physics, Chongqing University, Chongqing, China Han Dezhuan Department of Applied Physics, Chongqing University, Chongqing, China Xiao Jun Jun College of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, Guangdong, China

The concept of spoof surface plasmon polaritons (SSPPs) firstly developed by Pendry et al [1] has inspired numerous studies on plasmonics in terahertz and microwave bands. The main theme in this area is how to control and guide SSPPs in artificially designed plasmonic structures. We propose and study a multiscale spoof-insulator-spoof (MSIS) slot waveguide which possesses microwave band gap (MBG) due to the Bragg scattering [2]. The band structure of the fundamental symmetric SSPPs mode in the MSIS is analytically obtained by the Bloch theorem in the small gap approximation [see Fig. 1(a)], immediately offering the “gap maps” for all the geometry parameters. Finite element method (FEM) simulations show that the fundamental symmetric SSPPs mode has zero transmission for frequencies in the MBG [see Fig. 1(b)]. Moreover, a cavity mode is also observed in the MSIS by introducing a “point defect”. The band diagram of both the SIS [3] and MSIS waveguides are experimentally measured by a near-field scanning technique, with results comparable to numerical ones. The deep-subwavelength field confinement and the great degrees to control the propagation of SSPPs in MSIS structures promise potential applications in miniaturized devices for massive manipulation of microwaves.

Fig. 1. (a) GHz band structure of the proposed multiscale spoof-insulator-spoof waveguide by the small gap approximation (SGA) and by FEM (symbol+line). (b) Transmission of a finite-sized sample. Insets are the near field patterns at specific frequency marked by the arrows.

References:

[1] J. B. Pendry, L. Martín-Moreno and F. J. Garcia-Vidal, Science 305, 847 (2004).

[2] Q. Zhang, J. J. Xiao, D. Han, F. F. Qin, X. M. Zhang, and Y. Yao. Phys. Rev. B (submitted).

[3] M. A. Kats, D. Woolf, R. Blanchard, N. Yu, and F. Capasso, Opt. Express 19, 14860 (2011).

zhangqiang@hitsz.edu.cn









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