  Non-Hermitian topological systems have attracted lots of interest due to
their unique topological properties when the non-Hermitian skin effect (NHSE)
appears. However, the experimental realization of NHSE conventionally requires
non-reciprocal couplings, which are compatible with limited systems. Here we
propose a mechanism of loss-induced Floquet NHSE, where the loss provides the
basic source of non-Hermicity and the Floquet engineering brings about the
Floquet-induced complex next-nearest-neighbor couplings. We also extend the
generalized Brillouin zone theory to nonequilibrium systems to describe the
Floquet NHSE. Furthermore, we show that this mechanism can realize the
second-order NHSE when generalized to two-dimensional systems. Our proposal can
be realized in photonic lattices with helical waveguides and other related
systems, which opens the door for the study of topological phases in Floquet
non-Hermitian systems.
