Symmetry induced selective excitation of topological states in SSH waveguide arrays

TL;DR

This paper demonstrates a method to control topological states in SSH waveguide arrays by adjusting coupling ratios, enabling selective excitation and bi-directional transitions between symmetric and antisymmetric topological zero modes for advanced photonic applications.

Contribution

It introduces a novel switching strategy for inducing topological phase transitions between symmetric and antisymmetric zero modes in SSH waveguides through refractive index modulation.

Findings

Achieved bi-directional topological transitions between TZMs.

Demonstrated selective excitation of topological edge modes.

Showed potential for on-chip light flow control.

Abstract

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. Here, we report on topological phase transition between symmetric topological zero modes (TZM) and antisymmetric TZMs in Su-Schrieffer-Heeger (SSH) mirror symmetric waveguides. 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. Bi-directional topological transitions between symmetric and antisymmetric TZMs can be achieved with our 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.