▎ 摘　　要

Surface plasmon polariton (SPP) can be applied in light emission, sensing and imaging. In this work, by using a structure in which graphene is sandwiched between two dielectric mediums, we demonstrate a nonlinear response mechanism for generating low frequency transverse electric (TE) SPP in the terahertz (THz)/sub-THz regime. Furthermore, unlike any other known SPPs located outside the light cone, a significant part of the nonlinear low frequency TE SPP mode revealed here falls in the light cone. Therefore, it is possible to couple the SPP directly with light without structural modifications, making it a possible radiation source in low frequencies. (C) 2019 The Japan Society of Applied Physics