Multi-band perfect plasmonic absorptions using rectangular graphene gratings

We propose to achieve multi-band perfect plasmonic absorptions with peak absorptivity >99% via the excitation of standing-wave graphene surface plasmon polaritons using single-layer graphene-based rectangular gratings. For the case with continuous gratings, perfect absorptions are only allowed for even-order modes, while the absorptions are quite low for odd-order modes because the fields are out-of-phase. However, for gratings with bottom-open configuration, four-band perfect absorptions containing both the even-and odd-order modes can be realized, which are found to be highly sensitive to the incident angle. The simulated results agree very well with the theoretical analyses by considering the phase path of the plasmonic waves. This multi-band absorber is a promising candidate for future plasmonic devices. (C) 2017 Optical Society of America