Graphene terahertz filter

In this paper we suggest and analyze numerically an electromagnetic filter for THz region. The filter is made of a frequency selective surface based on graphene elements placed on a dielectric substrate. The unit cell of the device represents a square lattice in which two graphene crosses are placed on both sides of a dielectric substrate. The two graphene elements interact and resonate with two dipole plasmonic modes with different frequencies due to difference in the geometrical sizes of the crosses. In the frequency between these two resonances there is a transparency window that characterizes the filtering property of the device. This effect can be explained by Fano resonance. The device operates at the central frequency 2.3 THz with the reflection and the transmission coefficients equal to -18.6 dB and -0.92 dB, respectively. We show also that the position of the transmission peak can be tuned by changing the chemical potential of the graphene.