Single-layer dual-band terahertz filter with weak coupling between two neighboring cross slots

A dual-band terahertz (THz) filter consisting of two different cross slots is designed and fabricated in a single molybdenum layer. Experimental verification by THz time-domain spectroscopy indicates good agreement with the simulation results. Owing to the weak coupling between the two neighboring cross slots in the unit cell, good selectivity performance can be easily achieved, both in the lower and higher bands, by tuning the dimensions of the two crosses. The physical mechanisms of the dual-band resonant are clarified by using three differently configured filters and electric field distribution diagrams. Owing to the rotational symmetry of the cross-shaped filter, the radiation at normal incidence is insensitive to polarization. Compared with the THz dual-band filters that were reported earlier, these filters also have the advantages of easy fabrication and low cost, which would find applications in dual-band sensors, THz communication systems, and emerging THz technologies.