▎ 摘　　要

Conventional all-dielectric metasurfaces show remarkable properties including high efficiency and tunability of the optical response. However, extreme narrow bandwidth is a limitation that reduce their application in the photonic sensor devices. In this work, an efficient hybrid silicon-graphene metasurface is numerically proposed and designed. Through the sandwiched graphene layer, the structure shows unique quarter-wave properties, tunable through the dimensions of silicon, the Fermi energy of graphene, and an external gate voltage. Dynamic tuning is achieved by reversing the gate voltage: circular polarization state is switched between the right- and the left-handed states by reversing the gate voltage. A 95% polarization conversion ratio and a 96% ellipticity ratio are obtained while converting linearly polarized light into circularly polarized light in the near infrared. Additionally, by integrating graphene with silicon, the Q-factor and the trapped magnetic modes in the silicon are effectively modulated. The structure is compact and has an ultrathin design thickness of similar to 0.1 lambda , in the telecommunication wavelength. The above properties are essential for integration into photonic sensing devices and for compatibility with the CMOS devices.