▎ 摘　　要

A proposal on optical bistability at ultralow switching threshold and lower Fermi-level of graphene around 2 THz is implemented analytically through the proposed long-range surface plasmon resonance configuration by employing local field enhancement effects owing to the excitation of a graphene symmetric mode within graphene sheets. Reported threshold intensity for the optical bistability to date is 1.6 kW/cm(2) within the terahertz region and 1.83 MW/cm(2) at near-IR range. Whereas the proposed scheme explores the possibility of reducing this threshold down to 143.68 W/cm(2), this technique proffers potential applications in nanoillumination, optical memory, and all-optical switching at an ultra-low threshold. (C) 2017 Optical Society of America