Tunability of the reflection and the transmission spectra of two periodically corrugated metallic plates, obtained by control of the interactions between plasmonic and photonic modes

We theoretically study the interactions between plasmonic and photonic modes within a structure that is composed of two thin corrugated metallic plates, embedded in air. We show that the interactions depend upon the symmetry of the interacting modes. This observation is explained by the phase difference between the Fourier components of the two gratings. The phase can be controlled by laterally shifting one grating with respect to the other. Therefore, this relative shift provides an efficient "knob" that allows to control the interaction between the various modes, resulting in an efficient modulation of light transmission and reflection in the proposed structure. Based on this concept we show that the investigated structure can be used as tunable plasmonic filter.