We demonstrated efficient nonlinear coupling between local vibrating molecules and propagating polariton modes at the vibration frequency (namely, mid-IR frequencies) using suspended graphene waveguides. Each waveguide deposited a micron-scale periodic metal (plasmonic) structure. Nonlinear effect, at very modest pump laser intensities has been demonstrated; these intensity levels are often used in ordinary Raman experiments. The polariton mode propagated through fairly long distances, several IR wavelengths long, without a substantial loss. Thus, the suspended graphene has established itself as a unique waveguide for the THz/infrared region.