▎ 摘　　要

We present an approach to engineer Bloch modes by using monolayer graphene decorated on the surfaces of periodic waveguides or incorporated in cavities. In the terahertz and far-infrared ranges, the presence of graphene brings about a tunable band shift to Bloch modes in periodic waveguides. Thus, propagating Bloch modes may become evanescent and vice versa for both TE and TM polarizations. The resonant wavelength in the cavities experiences a linear dependence on the graphene chemical potential, which also has an effect on the field localization and enhancement of the cavity modes. This study suggests that graphene modulated periodic waveguides and cavities may find great applications in terahertz ranges like tunable filters, switches, and modulators. (C) 2015 Optical Society of America