  We theoretically report an analog of photon-assisted tunneling (PAT) in a
periodically driven lattice array without a static biased potential by studying
a three-channel waveguide system. This analog of PAT can be achieved by only
periodically modulating the top waveguide and adjusting the distance between
the bottom and its adjacent waveguide. It is numerically shown that the PAT
resonances also exist in the five-channel waveguide system and probably exist
in the waveguide arrays with other odd numbers of waveguides, but they will
become weak as the number of waveguides increases. With origin different from
traditional PAT, this type of PAT found in our work is closely linked to the
existence of the zero-energy (dark) Floquet states. It is readily observable
under currently accessible experimental conditions and may be useful for
controlling light propagation in waveguide arrays.
