Nanoscale contact electrodes for significant radiation power enhancement in photoconductive terahertz emitters

We present a photoconductive terahertz emitter that incorporates nanoscale plasmonic contact electrodes to offer significantly higher radiation powers compared to conventional photoconductive terahertz emitters. Radiation enhancement is the result of reducing the average transport path of photogenerated carriers to the plasmonic contact electrodes and, thus, increasing the number of the photocarriers that can be routed to the terahertz antenna in a sub-picosecond time-scale to efficiently contribute to terahertz radiation. We experimentally demonstrate up to 50 times higher terahertz radiation powers from the presented plasmonic photoconductive terahertz emitter compared to a similar conventional photoconductive terahertz emitter without plasmonic contact electrodes.