Topological edge solitons in χ⁽²⁾ waveguide arrays

Area of Science:

• Nonlinear optics
• Topological photonics
• Condensed matter physics

Background:

• Topological phases of matter, like the Su-Schrieffer-Heeger (SSH) model, exhibit unique edge states.
• Nonlinear optical phenomena, such as second-harmonic generation (SHG), can be influenced by topological properties.
• Waveguide arrays provide a platform for realizing and studying topological phenomena in optical systems.

Purpose of the Study:

• To investigate the formation and properties of topological edge solitons in SSH waveguide arrays.
• To explore the role of phase mismatch in the behavior of these solitons.
• To identify mechanisms for controlling topologically nontrivial states using nonlinear interactions.

Main Methods:

• Theoretical analysis of nonlinear wave propagation in SSH waveguide arrays.
• Numerical simulations to identify and characterize edge solitons.
• Investigation of the influence of phase mismatch on soliton properties.

Main Results:

• Two distinct types of stable topological edge solitons were identified.
• One type bifurcates from the topological edge state of the fundamental frequency (FF) component without a threshold.
• The other type emerges above a power threshold, originating from the topological edge state of the second harmonic (SH) component.
• Soliton stability, localization, and internal structure are strongly dependent on the FF-SH phase mismatch.

Conclusions:

• Stable topological edge solitons can be formed in SSH waveguide arrays.
• Phase mismatch provides a crucial parameter for controlling the properties of these solitons.
• Parametric wave interactions offer a promising route for manipulating topologically nontrivial states in optical systems.