Tunable Edge States and Topological Solitons in Non‐Hermitian Photonic Lattices

Abstract Topological and non‐Hermitian optical systems underpin novel fundamental physical phenomena enabling the development of innovative photonic devices. The nonlinear properties of such systems are largely unknown, but they may introduce new opportunities for customized light control and routing in on‐chip photonic devices. In this article, tunable edge states and topological solitons are experimentally demonstrated in anti‐parity‐time symmetric non‐Hermitian Su–Schrieffer–Heeger lattices created in a Fe‐doped lithium niobate crystal. A photonic nontrivial Su–Schrieffer–Heeger lattice with tailored loss is fabricated and the tunable non‐Hermitian edge states within the topological gap are observed. Furthermore, the calculations of the eigenvalue spectrum and the Zak phase analog in the nonlinear regime reveal that nonlinearity can actively tune non‐Hermitian topological edge states. The topological properties of the nonlinear edge solitons are inherited from the linear topological edge states. Finally, the formation of nonlinear topological edge solitons are experimentally realized in this anti‐parity‐time symmetric non‐Hermitian lattice and real‐time self‐defocusing nonlinear manipulation of these edge states are directly observed. This work opens up new possibilities for unconventional light manipulation and potential device applications.