  Topological boundary states localize at interfaces whenever the interface
implies a change of the associated topological invariant encoded in the
geometric phase. The generically present dynamic phase, however, which is
energy and time dependent, has been known to be non-universal, and hence not to
intertwine with any topological geometric phase. Using the example of
topological zero modes in composite Su-Schrieffer-Heeger (c-SSH) waveguide
arrays with a central defect, we report on the selective excitation and
transition of topological boundary mode based on dynamic phase-steered
interferences. Our work thus provides a new knob for the control and
manipulation of topological states in composite photonic devices, indicating
promising applications where topological modes and their bandwidth can be
jointly controlled by the dynamic phase, geometric phase, and wavelength in
on-chip topological devices.
