Coherent Control of Topological States in an Integrated Waveguide Lattice

Area of Science:

• Topological photonics
• Nanophotonics
• Solid-state physics

Background:

• Topological photonics offers robust light localization and propagation via system symmetries.
• Conventional designs use lattice symmetries, but accidental degeneracies in meta-atoms present an alternative.
• Engineered accidental degeneracies can lead to novel topological phases.

Purpose of the Study:

• To experimentally realize and control topological edge states in silicon nanostructured waveguides.
• To explore the impact of engineered accidental degeneracies on topological phase formation.
• To demonstrate selective excitation of bulk versus edge states.

Main Methods:

• Fabrication of silicon nanostructured waveguides with pairs of degenerate modes.
• Exploitation of the hybrid nature of topological modes for coherent control.
• Phase adjustment between degenerate modes to control light propagation.
• Third harmonic generation imaging to visualize field distributions.

Main Results:

• Experimental realization of topological edge states in silicon nanophotonic arrays.
• Demonstration of selective excitation of bulk or edge states by controlling the phase of degenerate modes.
• Visualization of topological mode localization as a function of excitation phase.
• Confirmation of engineered accidental degeneracies driving topological phase formation.

Conclusions:

• Engineered accidental degeneracies provide a viable route to topological phases in photonic systems.
• Coherent control of topological modes is achievable by manipulating degenerate modes.
• This work expands the design principles for topological nanophotonic devices.
• Potential for enhanced robustness in light localization and propagation applications.