The characteristics of a terahertz filter with three-layer stacked structure

The multi-layer stacked structure is often designed to realize a single functional filter. In this work, a multi-functional filter is proposed by stacking three-layered dielectrics and mounting two metallic bars on each dielectric. The filter characteristics have been analyzed and the numerical results indicate that the filter can be transformed from a multi-band filter to a broadband filter by varying structural parameters reasonably. Each resonance frequency of the triple-band and quad-band filter can be controlled independently by tuning the length of corresponding metallic bar. Additionally, the bandwidths of broadband filter can be modulated from 0.45 to 0.95 THz with the same filtering effects, and the transmission spectrum with two-sharp band sides almost keeps unchanged for the incident angle of THz wave from 0° to 23°. Furthermore, the mechanism of multi-band and broadband filters has also been investigated by analyzing the electric filed distributions.