Independent tuning of double plasmonic waves in a free-standing graphene-spacer-grating-spacer-graphene hybrid slab.

The independent excitation and tuning of double plasmonic waves are realized in a free-standing graphene-spacer-grating-spacer-graphene (GSGSG) hybrid slab, which consists of two graphene field effect transistors placed back-to-back to each other. Resulted from the high transparency and the tight confinement of surface plasmonic mode for the graphene, double plasmonic waves can be independently excited by guided-mode resonances (GMRs). Theoretical and numerical investigations are performed in the mid-infrared band. Furthermore, the tuning of individual GMR resonant wavelengths with respect to the system parameters is studied. The results provide opportunities to engineer the proposed hybrid slab for wavelength selective and multiplexing applications.