  Non-Hermitian skin effect and photonic topological edge states are of great
interest in non-Hermitian physics and optics. However, the interplay between
them is largly unexplored. Here, we propose and demonstrate experimentally the
non-Hermitian skin effect that constructed from the nonreciprocal flow of
Floquet topological edge states, which can be dubbed 'Floquet skin-topological
effect'. We first show the non-Hermitian skin effect can be induced by pure
loss when the one-dimensional (1D) system is periodically driven. Next, based
on a two-dimensional (2D) Floquet topological photonic lattice with structured
loss, we investigate the interaction between the non-Hermiticity and the
topological edge states. We observe that all the one-way edge states are
imposed onto specific corners, featuring both the non-Hermitian skin effect and
topological edge states. Furthermore, a topological switch for the
skin-topological effect is presented by utilizing the gap-closing mechanism.
Our experiment paves the way of realizing non-Hermitian topological effects in
nonlinear and quantum regimes.
