Abstract-Experimental demonstration of ultra-wideband and high-efficiency terahertz spoof surface plasmon polaritons coupler

Heng-He Tang1, Tian-Jun Ma2 and Pu-Kun Liu1,a)


1 School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
2 Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China
a) Author to whom correspondence should be addressed. Electronic mail: pkliu@pku.edu.cn.
Appl. Phys. Lett. 108, 191903 (2016); http://dx.doi.org/10.1063/1.4948928

Spoof surface plasmonpolaritons (SSPPs) are promising for subwavelength waveguiding in the terahertz (THz) frequency range. However, they cannot be efficiently excited from spatial propagating or guided waves due to the mismatched momenta. In this paper, a THz coupler is designed to smoothly bridge SSPPs and guided (or propagating) waves. By using a tapered parallel-plate waveguide, the incident energies are efficiently compressed and coupled into a subwavelength gap. Then, the momenta differences are mitigated with a graded grating. The numerical simulations show that the relative bandwidth of the coupler reaches up to 127%, and the maximum coupling efficiency is 99%. More importantly, experiment results in the 0.22 THz–0.33 THz frequency range are also presented to verify the good performance of the coupler. The work provides a technical support for terahertz waveguiding.