  One-dimensional superlattices with modulated coupling constants show rich
topological properties and tunable edge states. Beyond the dimeric case,
probing the topological properties of superlattices is a challenge. Here we
suggest a rather general method of bulk probing topological invariants in
waveguide superlattices based on spatial displacement of discretized beams. A
judiciously tailored initial beam excitation of the lattice, corresponding to
superposition of Wannier functions, provides a direct measure of the band gap
topological numbers. For a quadrimeric superlattice, a simple bulk probing
method, which avoids Wannier states, is proposed to discriminate the existence
of zero-energy topological edge states from non-topological ones
