Tunable topological edge states based on anomalous scattering.

Area of Science:

• Condensed Matter Physics
• Photonics
• Materials Science

Background:

• Photonic crystals offer control over light propagation through photonic bandgaps (PBGs).
• Topological phases in photonic systems provide robust control over light, analogous to electronic topological insulators.
• Tuning topological properties in photonic crystals often requires complex fabrication or external stimuli.

Purpose of the Study:

• To design and demonstrate a novel 2D photonic crystal with tunable topological properties.
• To achieve topological phase transitions by manipulating composite scatterer geometry.
• To develop a programmable topological insulator for advanced photonic applications.

Main Methods:

• Fabrication of composite scatterers using dielectric materials and metal foils.
• Construction of a 2D square lattice photonic crystal.
• Utilizing Mie scattering resonances for PBG formation.
• Controlling topological properties via rotation of composite scatterers within the unit cell.
• Development of a single-chip control system (SCCS) for experimental verification.

Main Results:

• Achieved tunable topological edge states (TES) by altering scatterer rotation angles.
• Demonstrated topological phase transitions through controlled rotation.
• Verified numerical predictions with experimental results using the SCCS.
• Showcased the ability for arbitrary coding and programmable control of topological states.

Conclusions:

• The proposed composite scatterer design enables dynamic control over photonic band topology.
• This work presents a new platform for programmable topological insulators.
• The findings pave the way for novel photonic devices with tunable edge states and arbitrary coding capabilities.