Terahertz detection sensitivity enhancement by incorporating plasmonic gratings in photoconductive detectors

We present a design of plasmonic photoconductive detectors, which mitigates the low detection sensitivity limitation of conventional photoconductive terahertz detectors. By incorporating plasmonic contact electrode gratings in the photoconductive detector, average carrier transport path length to the contact electrodes is reduced, enhancing photoconductor responsivity significantly. As a proof of concept, comparable conventional and plasmonic photoconductive detector prototypes were fabricated and characterized in the same time-domain terahertz spectroscopy setup. Experimental results show that a 30 fold terahertz detection sensitivity enhancement can be achieved over 0.1 THz to 1.5 THz frequency range by using the presented plasmonic photoconductive detector.