Enhanced polarization sensitivity by plasmonic-cavity in graphene phototransistors

Polarization detection is a powerful tool to enhance the information recognition of objects. Although the photodetectors based on graphene with distinguished features have been considered promising for high-performance light perception applications, they are typically polarization insensitive. We proposed and experimentally achieved a plasmonic-cavity integrated graphene phototransistor for polarization detection. The plasmonic cavity enhances the photoresponse of transverse magnetic waves and restrains that of transverse electric waves, leading to a remarkable polarization extinction ratio as high as 30, surpassing those of all previously reported two-dimensional material-based polarization sensitive photodetectors by 3–10 times. In addition, for the selected polarization, the photoresponse is enhanced by more than one order of magnitude due to the enhanced localized field. We chose near-infrared for demonstration, while the principle is applicable to other wavelength ranges.