Broadband Mode Division Multiplexer Based on Terahertz Spoof Surface Plasmon Polaritons

In this paper, a broadband mode converter based on terahertz spoof surface plasmon polaritons is demonstrated. The incident surface waves in the TM
0
mode are converted to the TM
1
mode within the frequency range of 0.55–0.75 THz. Furthermore, a broadband mode division multiplexer is proposed, which simultaneously supports the TM
0
, TM
1
and TM
2
modes. The length of the whole device is about 14 times of the wavelength. For the first time to our knowledge, a mode division multiplexer based on terahertz spoof surface plasmon polariton is reported.