Reversible modulation of reconfigurable topological optical bistability with dual-band in mid-infrared

We present a flexible scheme enabling reversible switching of topological states and dynamic modulation of optical bistability in a fixed micro-nano nonlinear optical system. The system realizes the optical modulation of reconfigurable topological edge states through phase transition-induced optical property changes in Ge₂Sb₂Te₅. The third-order nonlinear optical effects of the system are effectively enhanced by local field enhancement in the dual-band via reconfigurable topological edge states, which have a positive impact on the realization of dual-channel modulated optical bistability. In particular, electric field distributions within parameter subspaces are mapped to demonstrate multi-degree-of-freedom dynamic control of OB under fixed pump intensity by tuning graphene's Fermi level, relaxation time, layer number, and incident angle. Meanwhile, the simulation results agree well with the calculation, proving that the modulated dual-channel optical bistability via reconfigurable topological edge states based on phase change materials can be achieved, which provides a viable solution to address the lack of multidimensional optical modulation of fixed micro-nano nonlinear optical systems in the mid-infrared band.