Tunable mid-infrared plasmonic band-pass filter based on a single graphene sheet with cavities

Abstract

The single graphene sheet with two cavities constructed on substrates is proposed and numerically investigated by using the finite-difference time-domain (FDTD) method. Thanks to the two introduced cavities, the sandwiched graphene strip behaves as a line-shaped plasmonic resonator. The simple single graphene sheet hence exhibits an outstanding band-pass filtering effect. The transmission spectrum is tuned dynamically not only via changing the length of the graphene strip sandwiched in cavities but also by a small change in the chemical potential of graphene. Simulation results are confirmed by the standing wave equation. In addition, the wavelength of the transmission peak can be tuned linearly by changing the substrate and the proposed structure hence has potential applications in mid-infrared plasmonic sensors. The transmission spectrum is also optimized by changing the width of the cavity. Our studies may be important for the fabrication of nano-integrated circuits for optical communication in the mid-infrared region.