Topological photonic alloy

Abstract

We present the new concept of photonic alloy as a non-periodic topological material. By mixing non-magnetized and magnetized rods in a non-periodic 2D photonic crystal configuration, we realized photonic alloys in the microwave regime. Our experimental findings reveal that the photonic alloy sustains non-reciprocal chiral edge states (CESs) even at very low concentration of magnetized rods. The non-trivial topology and the associated edge states of these non-periodic systems can be characterized by the winding of the reflection phase. Our results indicate that the threshold concentrations for the investigated system within the first non-trivial band gap to exhibit topological behavior approach zero in the thermodynamic limit for substitutional alloys, while the threshold remains non-zero for interstitial alloys. At low concentration, the system exhibits an inhomogeneous structure characterized by isolated patches of non-percolating magnetic domains that are spaced far apart within a topologically trivial photonic crystal. Surprisingly, the system manifests CESs despite a local breakdown of time-reversal symmetry rather than a global one. Photonic alloys represent a new category of disordered topological materials, offering exciting opportunities for exploring topological materials with adjustable gaps.

6 pages, 4 figures

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• Fibonacci-Modulation-Induced Multiple Topological Anderson Insulators
• Band alignment effect in the topological photonic alloy
• Random-Flux-Induced Transition Sequence between Weak and Strong Topological Phases with Anisotropic Localization Properties
• Recent progress on disorder-induced topological phases
• Disorder-driven exceptional points and concurrent topological phase transitions in non-Hermitian systems
• Magnetic doping-induced second-order and first-order topological phase transition inthe photonic alloy
• Topological Anderson insulator and reentrant topological transitions in a mosaic trimer lattice
• Weak coupling theory of nickel-based 327 superconductors