  Amongst the wide spectrum of potential applications of graphene, ranging from
transistors and chemical-sensors to nanoelectromechanical devices and
composites, the field of photonics and optoelectronics is believed to be one of
the most promising. Indeed, graphene's suitability for high-speed
photodetection was demonstrated in an optical communication link operating at
10 Gbit/s\cite. However, the low responsivity of graphene-based photodetectors
compared to traditional III-V based ones is a potential drawback. Here we show
that, by combining graphene with plasmonic nanostructures, the efficiency of
graphene-based photodectors can be increased by up to 20 times, due to field
concentration in the area of a p-n junction. Additionally, wavelength and
polarization selectivity can be achieved employing nanostructures of different
geometries.
