A silicon based source for radiation in the 0.5-14 Terahertz regime. This new class of devices will permit continuously tunable, milli-Watt scale, continuous-wave, room temperature operation, a substantial advance over currently available technologies. The Silicon Terahertz Generator (STG) employs a silicon waveguide for near infrared radiation, situated within a metal waveguide for Terahertz radiation. A nonlinear polymer cladding permits two near-infrared lasers to mix, and through difference frequency generation produces Terahertz output. The small dimensions of the design greatly increase the optical fields, enhancing the nonlinear effect. The design can also be used to detect Terahertz radiation.