  We report here fabrication of interdigitated photoconductive antenna (iPCA)
terahertz (THz) emitters based on plasmonic electrode design. Novel design of
this iPCA enables it to work without microlens array focusing, which is
otherwise required for photo excitation of selective photoconductive regions to
avoid the destructive interference of emitted THz radiation from oppositely
biased regions. Benefit of iPCA over single active region PCA is that photo
excitation can be done at larger area, hence avoiding the saturation effected
at higher optical excitation density. The emitted THz radiation power from
plasmonic-iPCAs is ~ 2 times more than the single active region plasmonic PCA
at 200 mW optical excitation, which will further increase at higher optical
powers. This design is expected to reduce fabrication cost of photoconductive
THz sources and detectors.
