High-efficiency terahertz emitters based on three-dimensional metallic nanostructures

We present a photoconductive terahertz emitter that incorporates three-dimensional metallic nanostructures inside the device active area to offer record high optical-to-terahertz power conversion efficiencies. By use of three-dimensional metallic nanostructures the majority of photocarriers are generated within nanoscale distances from the photoconductor contact electrodes and drifted to the terahertz radiating antenna in a sub-picosecond time scale to efficiently contribute to terahertz radiation. We experimentally demonstrate 105 μW of broadband terahertz radiation in the 0.1-2 THz frequency range in response to a 1.4 mW optical pump, exhibiting a record high optical-to-terahertz power conversion efficiency of 7.5%.