Topological Waveguides

Speaker:Che Ting Chan

Venue: Lecture Hall 201, Haina Complex Building 4, Zijingang Campus

Abstract: Topologically protected boundary states enable unidirectional wave propagation, offering a novel approach for photonic/phononic devices that resist backscattering caused by structural defects or disorder. However, wave propagation in such systems is confined to the boundaries between topologically distinct phases. Since the boundary state channels for energy/signal transmission must be flanked by topological insulator materials characterized by band gaps defined by topological invariants, their effective transmission area is significantly smaller than the overall device area. Consequently, achieving robust unidirectional transmission comes at the cost of spatial efficiency, as the bulk material regions merely function as cladding structures. To overcome this limitation, we attempt to achieve 100% spatial utilization by constructing topological waveguides. Furthermore, we will demonstrate that certain special waveguide networks exhibit unique wave propagation characteristics similar to those of topological photonic crystals, making them practically valuable for exploring topological physics.