Terahertz Generation from a Bias-Free, Telecommunication-Compatible Photoconductive Emitter Realized on a Silicon Substrate

We present a telecommunication-compatible, bias-free photoconductive terahertz emitter realized on a silicon substrate, which incorporates a large area plasmonic nanoantenna array to achieve high-efficiency and broadband terahertz generation. By maximizing the spatial overlap between the plasmonics-enhanced optical generation profile and a naturally-induced built-in electric field near the semiconductor surface, a large fraction of the photocarriers drift to the nanoantennas without requiring any external bias voltage, leading to highly efficient optical-to-terahertz conversion with high reliability. Realizing this terahertz emitter concept on silicon enables integration with other silicon photonic platforms, as well as a significant enhancement in the radiation power at high terahertz frequencies.