High-speed electro-optic modulators in silicon platform are introduced and experimentally verified. The devices rely on plasmonic and photonic slot waveguides and are combined with efficient organic electro-optic materials. The bandwidth limitation of conventional silicon-organic-hybrid modulators is circumvented by capacitive coupling of the microwave signal. An advanced terahertz link that upconverts data directly from a 360 GHz carrier to an optical carrier is demonstrated for the first time ...