Self-localized states in photonic topological insulators

Area of Science:

• Photonics
• Topological Insulators
• Nonlinear Optics

Background:

• Topological insulators exhibit unique edge states with unidirectional transport properties.
• Photonic topological insulators leverage light propagation in engineered structures to mimic electronic topological states.
• Nonlinearity in optical systems can lead to self-localization of light, forming solitons.

Purpose of the Study:

• To propose and theoretically investigate the existence of solitons within the bulk of a nonlinear photonic topological insulator.
• To demonstrate that these bulk solitons can exhibit unidirectional transport properties, analogous to edge states.
• To explore the formation mechanism of such solitons in a specific system, a Floquet topological insulator with a honeycomb lattice of waveguides.

Main Methods:

• Theoretical modeling of light propagation in a nonlinear photonic topological insulator.
• Analysis of wave packet dynamics and self-localization due to nonlinear-induced defects.
• Investigation of edge state population and transport properties of the formed solitons.

Main Results:

• Self-localized wave packets (solitons) are proposed to form within the bulk of a nonlinear photonic topological insulator.
• These bulk solitons exhibit unidirectional transport, a characteristic typically associated with topological edge states.
• In a Floquet topological insulator model, solitons induce defects and populate rotating edge states, enabling this transport.

Conclusions:

• The concept of solitons residing in the bulk of nonlinear topological insulators and exhibiting unidirectional transport is established.
• This phenomenon offers a novel mechanism for controlling light transport in topological photonic systems.
• The proposed concept is general and applicable to various nonlinear topological systems.