Dual-band topological refractive properties in solid phononic crystals

• Published in: Physics letters. A Vol. 525; p. 129881
• Main Authors: Chu, Yangyang, Sun, Tong, Wang, Zhaohong, Zhang, Zhifeng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2024
• Subjects: Dual-frequency topological state; Dual-topological refractive; Negative refraction; Topological edge states; Zero refraction; Dual-topological refractive; Topological edge states; Dual-frequency topological state; Negative refraction; Zero refraction
• ISSN: 0375-9601
• DOI: 10.1016/j.physleta.2024.129881

•Acoustic topological insulators have two topological edge states.•Breaking the space inversion symmetry of phononic crystals can open two Dirac points simultaneously and produce band inversion.•The topological negative refraction of valley projection edge states exists at the low-frequency bandgap, while the topological zero refraction of pseudo spatial edge states exists at the high-frequency bandgap. The lossless transmission of topological edge states and the robustness of defect immunity make topological refractive materials have important application prospects in acoustic communication and integrated acoustic devices. However, most topological refractive materials only have a single operating frequency band, which obviously limits their application in multi-band and multi-function devices. Therefore, a phononic crystal with dual-frequency topological states is designed in this paper, and its dual-topological refractive properties are investigated and discussed. The existence of in-plane bulk elastic wave edge states is demonstrated by calculating the band structure of supercell comprising phononic crystals with different topological phases. Numerical simulations of the constructed acoustic topological waveguide are performed and negative refraction is observed at the low bandgap while zero refraction is observed at the high bandgap. Then, the topological zero refraction is investigated for different incidence angles. The designed dual-band acoustic topological insulator has potential applications in multi-band acoustic communication and acoustic information processing.