High-efficiency photoconductive terahertz antennas based on high-aspect ratio plasmonic electrodes

We present a high-efficiency photoconductive antenna that incorporates three-dimensional plasmonic contact electrodes. Three-dimensional plasmonic contact electrodes facilitate ultrafast transport of the majority of photocarriers to the contact electrodes, enhancing the device quantum efficiency significantly. Under an optical pump power of 1.4 mW, we experimentally demonstrate 105 μW broadband terahertz radiation in 0.1-2 THz frequency range, exhibiting a record-high optical-to-terahertz conversion efficiency of 7.5%.