Identifying topological signature of 1D photonic lattice by Zak phase analysis and towards robust amplification of edge state

Light propagating through a periodic photonic lattice supporting Bloch modes is leaky in nature. Recently, it has been established that these 1D photonic lattices can provide robust lossless guidance of light by appropriate structural modulation following special models. However, these special models compel the structure to be quasi-periodic, which makes their fabrication less feasible. Thus, we propose a fabrication-feasible 1D periodic lattice having topological features, which is established by Zak phase analysis. We demonstrate the existence of an edge state in this specialty photonic lattice as well as its robustness against lattice dislocations. Through numerical simulation, we have also illustrated that these states can be amplified without any distortion by introducing homogeneous gain to the lattice substrate. This is a strikingly different phenomenon from the conventionally known fact that with the introduction of gain to periodic lattices, the propagating state of light spreads in the transverse direction due to enhanced complex coupling. Therefore, in this report, we present a study of the interplay between topology and non-Hermiticity from the standpoint of device application. Our findings suffice to propose the utility of these systems as on-chip optical interconnects and have the potential to be used as topological amplifiers within the regime of optical communication. (paper)