Terahertz(THz) technologies have numerous applications such as biological and medical imaging, security screening, remote sensing, and industrial process control. However, the lack of practical THz sources and detectors is still a significant problem to that limits the impact of these applications. In this Thesis work, three THz mechanisms are proposed and investigated, based on the distinctive electronic properties of charge carriers in single-layer graphene(including linear energy dispersion, large velocity, and ultra-high mobility.), combined with the use of nanoscale dielectric gratings. The first approach involves sinusoidally corrugated graphene sheets for the generation of THz light based on a fundamentally new cyclotron-like radiation process. Smith-Purcell radiation from charge carriers in the Graphene on a tow-dimensional array is the second mechanism. Finally, grating-coupled THz radiation from graphene plasmons will also be investigated. In all three cases, numerical simulations as well as fabrication and characterization activities will be carried out.