PT symmetric Floquet topological phase in SSH model

Highlights: • We find gapped quasi-energy spectrum for the periodical SSH model with gain and loss. • We show that Floquet topological insulating phase appears in the PT symmetric SSH model. • We discuss that stable topological phase exists in our system when the oscillation frequency is large. - Abstract: We consider periodically modulated Su–Schrieffer–Heeger (SSH) model with gain and loss. This model, which can be realized with current technology in photonics using waveguides, allows us to study Floquet topological insulating phase. By using Floquet theory, we find the quasi-energy spectrum of this one dimensional PT symmetric topological insulator. We show that stable Floquet topological phase exists in our model provided that oscillation frequency is large and the non-Hermitian degree is below than a critical value.