Abstract
We propose and analyze a graphene electromagnetic filter for the terahertz (THz) region. The filter represents a planar square array of graphene elements. A unit cell of the array is formed by two coaxial graphene rings placed on the opposite sides of a thin dielectric substrate. The two electromagnetically coupled rings resonate with dipole plasmonic modes. The rings have slightly different dimensions and consequently different yet close individual resonant frequencies. At a frequency lying between these two resonances, the currents in the two interacting rings have opposite directions. This leads to a suppression of the reflected from the array waves and consequently to a high transmission through the array. For the chemical potential of the graphene , the calculated quality factor of this resonant mode is at the frequency . At this frequency, the reflection coefficient of the array equals and the transmission peak which is defined by the graphene losses is . We show that the frequency position of the transmission peak can be varied in a wide range by the graphene chemical potential.
© 2015 Optical Society of America
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