Probing one-dimensional topological phases in waveguide lattices with broken chiral symmetry

One-dimensional lattices with chiral symmetry are known to possess quantized Zak phase and nontrivial topological phases. Here it is shown that the quantized Zak phase and nontrivial edge states, partially protected by inversion symmetry rather than chiral symmetry, can be observed and probed in the bulk exploiting continuous-time photonic quantum walk in zig-zag waveguide arrays. The averaged beam displacement measurements can detect quantized Zak phase and nontrivial topological phases in the extended Su–Schrieffer–Heeger model with broken chiral symmetry.