The dispersive and transmission properties of terahertz waves through subwavelength metal-dielectric-metal structure have been investigated by using the transfer matrix method. The effects of the geometrical parameters, radiation frequency and dielectric filling materials on the propagation properties of gap surface plasmon polaritons modes have been explored. The results show that as the length of the dielectric filling materials increases, the effective index of the propagation modes increases, the propagation loss shows a peak at certain strip length, which are very useful to find the optimal sample size to improve detection sensitivity.
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