Topological phase transitions and Weyl semimetal phases in chiral photonic metamaterials

Recently, topologically nontrivial phases in chiral metamaterials have been proposed. However, a comprehensive description of topological phase diagrams and transitions in chiral metamaterials has not been presented. In this work, we demonstrate several forms of topological phase transitions and study the existence of edge states in different phases. In the local/lossless chiral media system, the topological phase transitions are associated with Weyl points. Along with the transitions, the edge state and Fermi arc exhibit a series of changes. When the nonlocal effect is introduced, the system shows phase transition between type-I/II Weyl semimetal phase and trivial phase. Moreover, the dissipative system also undergoes topological phase transitions owing to the annihilation of the topological charges. Our work could be helpful for the application of topological concepts and rich the topological wave physics in metamaterials.