  This paper presents a novel analytical model for chiral multi-layer
waveguides incorporating graphene sheets. The general structure is composed of
various chiral layers, where a graphene sheet has been sandwiched between two
adjacent chiral layers. We have chosen and studied this general structure to
suggest a new platform for novel emerging sciences such as optical sensing. An
analytical model has been proposed for the general structure to find its
dispersion relation and other modal properties such as the effective index and
the propagation length. To show the richness of our general structure, two
novel chiral waveguides containing graphene sheets have been introduced and
investigated. Our analytical results show that high values of effective
indices, e.g. neff=15 at the frequency of 8 THz for the second structure, is
achievable. Moreover, it has been shown that the chemical potential of the
graphene and the chirality can adjust and control the plasmonic features. Our
multi-layer structure and its analytical model can be utilized in several
potential applications such as switches, absorbers, cloaks, polarization
rotators, and directional couplers in the THz frequencies.
