Observation of Light Localization at the Edges of Quasicrystal Waveguide Arrays

Area of Science:

• Photonics and Light Localization
• Condensed Matter Physics
• Materials Science

Background:

• Quasicrystals possess long-range order without translational symmetry, offering unique system properties.
• Light propagation in photonic quasicrystal bulk is understood, but edge localization remains largely unexplored experimentally.
• Truncation of photonic quasicrystal structures significantly influences light behavior.

Purpose of the Study:

• To experimentally investigate linear and nonlinear light localization at the edges of truncated photonic quasicrystal waveguide arrays.
• To theoretically analyze the influence of truncation radius on edge light localization.
• To confirm the existence of localized states and observe nonlinear effects, including edge solitons.

Main Methods:

• Theoretical analysis of light propagation in radially cropped quasicrystal waveguide arrays with aperiodic Penrose tiling.
• Experimental fabrication of Penrose quasicrystal arrays using femtosecond laser inscription.
• Single-waveguide excitation to probe linear localized states and nonlinear phenomena.

Main Results:

• Theoretical predictions confirmed that specific truncation radii lead to linear eigenstates localized at the array edge.
• Experimental validation of localized states in femtosecond laser-inscribed Penrose quasicrystal arrays.
• Observation of a transition from linear localized states to edge solitons with increasing input pulse power.

Conclusions:

• Selective truncation of quasiperiodic photonic systems can induce significant edge light localization phenomena.
• The study provides the first experimental demonstration of localization effects in truncated quasicrystal photonic systems.
• Edge solitons were theoretically identified and experimentally observed, highlighting the role of nonlinearity.