Symmetry-Induced Selective Excitation of Topological States in Su-Schrieffer-Heeger Waveguide Arrays

The investigation of topological state transition in carefully designed photonic lattices is of high interest for fundamental research, as well as for applied studies such as manipulating light flow in on-chip photonic systems. Herein, the topological phase transition between symmetric topological zero modes (TZM) and antisymmetric TZMs in Su-Schrieffer-Heeger mirror symmetric waveguides is reported. The transition of TZMs is realized by adjusting the coupling ratio between neighboring waveguide pairs, which is enabled by selective modulation of the refractive index in the waveguide gaps. Bidirectional topological transitions between symmetric and antisymmetric TZMs can be achieved with proposed switching strategy. Selective excitation of topological edge mode is demonstrated owing to the symmetry characteristics of the TZMs. The flexible manipulation of topological states is promising for on-chip light flow control and may spark further investigations on symmetric/antisymmetric TZM transitions in other photonic topological frameworks. Herein, the selective excitation of trivial/nontrivial topological states by switching the symmetry of the topological zero modes (TZM) in Su-Schrieffer-Heeger waveguide arrays is reported. Bidirectional topological transitions between symmetric and antisymmetric TZMs can be achieved with proposed strategy. Selective excitation of topological edge mode is demonstrated owing to the symmetry characteristics of the TZMs.image (c) 2023 WILEY-VCH GmbH