Topological Optical Waveguiding in Silicon and the Transition between Topological and Trivial Defect States

One-dimensional models with topological band structures represent a simple and versatile platform to demonstrate novel topological concepts. Herewe experimentally study topologically protected states in silicon at the interface between two dimer chains with differentZak phases. Furthermore, we propose anddemonstrate that, in a system where topological and trivial defect modes coexist, we can probe them independently. Tuning the configurationof theinterface, weobserve thetransitionbetweena single topologicaldefectandacompoundtrivial defect state. These results provide a new paradigmfor topologically protectedwaveguiding in a complementary metal-oxide-semiconductor compatible platform and highlight the novel concept of isolating topological and trivial defect modes in the same system that can have important implications in topological physics.