Plasmon-Enhanced Infrared Absorption in Graphene Nanodot Array

Novel optical properties of the nanopatterned graphene in the infrared and terahertz can be enhanced and tailored. The underlying nature is the excited plasmon of the patterned graphene with sub-wavelength feature sizes induce high optical field confinement, low intrinsic loss, and diverse optical tunability. Thus, high-quality graphene nanoarrays with fine nanostructures and low surface roughness should be needed to precisely adjust the graphene plasmon-enhanced optical properties. Here, electron beam exposure and inductively coupled plasma (ICP) etching techniques were used to fabricate the single-layer graphene nanodot array (GNDA) with a minimum size of 90 nm and a surface roughness of 0.846 nm. The measured absorption spectra in the infrared and terahertz range show an enhanced absorption compared to the unpatterned graphene, and a maximum rate of 10% is adopted in the infrared spectra. The absorption peaks undergo a slight red shift with the dot size increase. The experimental results show a good agreement with the numerical simulation. The results in our work provide a path to design and fabrication of novel photodetectors based on graphene’s plasmonic excitations with good light sensitivity and frequency selectivity.