Highly tunable and sensitive plasmon induced transparency modulator with graphene metasurface

Abstract

In this paper, we have proposed a monolayer graphene metasurface to achieve excellent functions of optical filter , slow light, optical switcher which results from the plasmon induced transparency (PIT). The designed structure comprises of a cross and a circle-shaped graphene resonators. A distinct PIT transparency window originating from the bright-bright mode coupling is investigated based on the analysis of the electric field distribution and the coupled mode theory. Moreover, a tunable dual-frequency on to off modulator and an outstanding slow light effect are achieved through the phase modulation of PIT. And the transparency window substantially shifts into the high frequency region with a larger Fermi energy. Finally, the electric fields polarized along the x and y direction show the same distribution due to the central symmetry of the metasurface, verifying the polarization insensitive performance in our design. Thus, our numerical results provide an important guidance in the design of excellent sensors and photonic devices in terahertz region. • A tunable dual-frequency on to off modulator and an outstanding slow light effect are achieved based on the phase modulation of PIT. • The maximum sensitivity is 2.99 THz/RIU, and maximum figure of merit (FOM) is 69.69 with different surrounding medium. • The electric fields polarized along the x and y direction shows the same distribution due to the central symmetry of the metasurface, verifying the polarization insensitive properties.