  Recently, optical soliton propagation in an intrinsic nonlinear graphene
monolayer configuration has been discovered. However, optical soliton behavior
in a free-standing graphene monolayer with defects has not yet been studied.
The objective of this article is to employ the generalized finite- difference
time-domain (G-FDTD) method to efficiently simulate bright optical solitons,
illustrating propagation of the electric field distribution in a free-standing
nonlinear layer with variation in nonlinearity along its width. These
variations of nonlinearity along the width represent graphene impurities, or
defects. Results show that solitons propagate effectively even in the presence
of strong spatial variations in the nonlinearity, implying the robustness of
the medium with respect to optical propagation.
