Plasmonic photoconductive detectors for enhanced terahertz detection sensitivity

A photoconductive terahertz detector based on plasmonic contact electrodes is presented. The use of plasmonic electrodes mitigates the inherent tradeoff between high quantum efficiency and ultrafast operation of the employed photoconductor, enabling significantly higher detection sensitivities compared to conventional photoconductive terahertz detectors. Prototypes of comparable photoconductive detectors with and without plasmonic contact electrode gratings were fabricated and characterized in a time-domain terahertz spectroscopy setup under the same operation conditions. The experimental results show that the plasmonic photoconductive detector offers more than 30 times higher terahertz detection sensitivities compared to the comparable conventional photoconductive detector without plasmonic contact electrodes over 0.1-1.5 THz frequency band.